For the folks that might think this video is rudimentary in nature, remember who the target audience is. People who are interested in hot rodding (and perhaps spending a few dollars) but who also have a lot of competing interests in their family budget… Videos like this keep the interest up and keep the money flowing into the hobby and help all of us who provide some type of engine improvement service. Keep up the good work Eric.
I looked at cams differently once I made a cardioid equation for cams. You mentioned things that directly reflect what I got out of the situation. A main takeaway I got was the shape of the power curve. That made it easier to plan simpler builds that don't even rev higher than stock, but still run great. Life don't have to be so complicated.
Great introduction, I feel if people roled up their sleeves got to know how the numbers work make a few phone calls it would really help know what they are getting and know who's blowing smoke, great video
All of your videos are great. Thank you for sharing all of this information. I’m never too old to learn, as a matter of fact, I’m always eager to learn more. Keep them coming. You’ve got some of the best content here on RUclips. Thanks again for sharing 😉👍
thanks for sharing all the information with us I have learned alot from watching your channel I love all the detail you go into! I am a drag racer also and I am always trying to improve my engine performance you have helped me to understand how it all works to make a engine run better. thanks again!
I started studying cams after picking one for my motorcycle back in 2005. I wanted a good street engine and picked a cam advertised to meet my needs, I thought. The engine was a 4-cam Harley (Sportster) that I bored from 883 to 1250, courtesy of a 3-9/16” bore. The cam had 256° intake duration at 0.050” and 0.493” lift at the valve. With the heads I switched to, it made power at 6000, about 84 hp at the wheel, and flat torque curve between 4-5000 rpm. This was about double the original 883 power, but nothing like what others got from modified Sportsters. Your point about lift is what I missed on that cam selection. A few years later, and after studying for a while, I went a totally different way on cams for my 103 Twin Cam, a Woods 222. With a 103° intake centerline, this has an intake closing of 34°, way shorter than that Sportster cam. I don’t remember the exact numbers for the “493” cam, but it was probably around 99° intake CL, or 47° IC ABDC. Typically an under square engine, smaller bore than stroke, is going to need more duration than one with more area, relatively, on top of the piston. The Twin Cam is bigger, 3.875x4.375 compared to 3.563x3.813, but the heads flow more and the lift is 0.575”, a lot more. Both are small bore engines. The Twin Cam gets to 100 lb-ft of torque at the wheel at about 2500 rpm and stays there to 4500 or so, with a max of 104. The horsepower peak is around 5700. Overall it’s very strong for street riding for a 900 lb bike. Not a competition machine by any means! So, you ask, what has that got to do with V8s? Based on my limited experience and some study, the significant numbers for cam selection are valve lift, intake closing (IC), and overlap. In this video, Eric mentioned 100° intake centerline on a cam with 240° intake duration, about 104° LSA, and almost 0.650” lift. Intake closing can be easily computed from duration and centerline as 240 divided by 2 plus centerline minus 180, or 240/2=120, 120+100=220, 220-180=40, which means IC is at 40° ABDC. If the new cam is installed 4° advanced as well, it’s intake centerline will be at 104, so 248/2=124, 124+104=228, and 228-180=48 for intake closing, substantially more. With another 0.100” or so of lift, this cam is going to make a lot more top end than the Engine Masters cam, which had a different purpose (and limitations). Overlap is the other significant variable. It is also fairly simple to compute given duration at 0.050 for both intake and exhaust lobes and LSA. Intake opening BTDC is (for the old cam) 240/2=120, 120-100=20 and exhaust closing is 246/2=123, 123-108=15 ATDC, or 35° of overlap at 0.050” tappet lift. Note the LSA comes in as intake centerline is advanced from LSA (a lower number), exhaust centerline moves the other way (bigger number). The new cam, with a bit more LSA and longer duration computes as 248/2=124, 124-104=20 BTDC and 253/2=126.5, 126.5-112=14.5 ATDC, or nearly identical overlap to the earlier cam. Eric has real world experience picking cams for himself and customers, and it sounds like he is way better than average at speccing them, despite his claims. The heart of any engine is based on heads, cam and intake (mostly effective runner length) performance. Watchers could do themselves a favor listening to him! Eric, you have a great channel here, thanks!
So if you've got your intake and exhaust set up to work with a certain amount of overlap you don't want to mess with that when your making a cam change or if you do you would want to be aware of how much and if you're shifting it forward or backwards.
@@luckyPiston Most people quote intake duration and LSA to describe a cam. Brian Tooley said once that the valve events need to be what they need to be, or some words to that effect. Looking at his cams, I find that the overlap is often symmetrical, at least for LS engines. If you’re trying to get power out of the overlap event, that makes sense to me. The amount of overlap needed is generally a function of displacement vs cylinder head effectiveness, with bigger engines needing more. The more aggressive the cam (or the higher the rpm range), the more overlap as well. My motorcycle engines, being relatively small bore/long stroke, needed LOTS of overlap while the LS with its great breathing needs less. Overlap is bad for idle quality and somewhat for emissions, but makes a big difference in mid-range torque. That’s why Holdener’s cam comparisons sometimes show more torque through the entire rpm range he tests. Factory cams typically have none, thus the poor torque curve comparison. Eric seems to have figured the ideal amount of overlap for his engine and specced a cam that changed only the other end of each valve event. Sorry for the windy reply…
@@bdugle1 No worries, Some good points there, interesting how a stroker likes more OL, my first thought is piston dwell time with the stroker is longer so why more OL and not less ? So what are your thoughts on dual pattern cams. I think they hurt power down low yet they are the predominant choice. Even when specing an engine that has plenty of exhaust flow people are still running dual pattern (in a street engine this makes no sense) my thought is with so many new heads on the market with improved exhaust you would think you would see more single pattern profiles. No one ever talks about how hot exhaust gas flows waaay better than what is in the cooler intake tract ? Density is enough of a factor that we have to correct for weather on our flow bench to get repeatability yet its never mentioned with gas exiting an engine.
@@luckyPiston I picked a cam for my 6.0 with strong street manners in mind, but I don’t claim to be an expert in selecting one for any combination. I have picked up a lot of general rules since starting to study cams in the last 15 or 20 years, however. I know a under-square engine is going to need more duration and more overlap, but picking precise numbers for a particular application for someone else is something I would not attempt. As far as dual pattern cams-I think most applications seem to like them but single pattern cams can work well, too. The Comp 459 and 469 cams have the same intake lobe but the rec port cam (469) has more exhaust duration. The 459 is reported to have a better idle while the 469 has a slight edge at the top when compared in the same engine (from watching Holdener videos, basically). The SS2 cam has much shorter exhaust duration, near single pattern, and shows a strong torque curve all across the dyno graph. That supports your feeling that a single pattern cam has a place, even though it doesn’t make the top end of the bigger cams. If you’re running a 5.3 or 6.0 it could be a really good choice. I’d say especially if turbocharged. I guess my rules would be get an expert’s recommendation on overlap, look for the highest lift you can get given the heads and valve train, and pick an intake closing point based on usage, displacement, and breathing limitations. Big BBCs need lots of duration while SBCs need moderate duration in the 355-383 size range. LSs need even less due to better stock heads. My Twin Cam bike cams intake close is at 34° which gives me a really strong low end. My LS cam has an intake valve closing of 42° which will run the power peak on a 6.0 out to low-to-mid 6000s. You undoubtedly have your own preferences for your engine. I know a lot more now than when running a 301 and a 327 in a C Gas dragster back in the 60s. There’s still lots to learn though!
Great information. Camshafts are a mystical and mythical thing to most people. What you have laid out here demonstrates the need for knowledgeable professional people to help in any project big or small. Awesome. Keep up the good work.
Don't worry, we enjoy hearing your opinion about these things. Do as many videos as you wish for any subject that you wish to cover. We will tough it through them with a smile on our faces. Getting good knowledge and information is not easy to get so we like to hear all we can. Besides we also feel that you may know a thing more than we do. I know a lot but I don't know everything so I listen to everyone and separate the good from the bad. This is how you learn.
🔔😎😁 I was hoping for more explanation of why 600 lift works better for a head flow that tops out at 500 lift. More area under the curve. Thanks for your time and thoroughness.👍👍😎😎
Good video. I used to be a camshaft engineer for an OEM. We used an Adcole brand cam inspection machine but CMMs were coming onto the scene and able to do just about everything the specialized machine could do.
Thank you so so much for your videos. I made a comment on your other video before finding this one. What i now know in comparison to what i still have to learn about my 4.0 straight 6 for my jeep has told me a lot of how much i dont know. I want to build it to be a 4.6L with a small turbo to get to an easy 325 to 350 hp which is relatively considering very high end builds have kicked out 300hp naturally aspirated. I want my motor to of course have more power but also have good longevity.
Eric!!!.. Excellent as ALWAYS!!. LOVED IT!!!... No such thing as too much for me!!.. I suck it up like sponge!!.. 55 years doing this!!. Always learning something new!!.
Good review of the key concepts, told in a way that those who may not be so "eye-balls deep" in this stuff will readily understand. I will tell you this, nothing frustrates me more than calling a cam company wanting to have a technical conversation (along the lines Eric explained here) and instead it feeling like I just ran into a brick wall: no desire to talk tech, no ability to do so, and instead it appears to be primairly a SALES pitch they want to do!!! Thanks Eric, good stuff...go deep on the techie stuff next!!!
Best cam video I’ve ever seen. We think alike. Don’t know how I missed this one I am a subscriber? Either way I am convinced you have a good head on your shoulders. Love profile is a major factor!
For visual people like me I think comparing the 2 lobes of lift vs duration would be easier to understand in a graph format. But this explained so much that I never truly understood in it's full context. It makes alot more sense now
I’m an Olds guy, I had a custom grind done for my current 455 build and kept an Olds friendly low lift spec. The heads were opened up to accept the “big” big block Olds valves along with some basic cleanup in the bowls and runners. I kept the lift low because the heads just don’t flow much above .500 so it seemed like needless stress (and expense) on the valvetrain. But I’m sure the quality of builds your doing far, far exceed the dinosaurs I’m messing around with. Great video, certainly quality food for thought.
Cheers for shearing your knowledge im about to set to clean up my Harley heads at this stage casting imperfections ive not done much in this kind of thing before but i cant stop watching your vids if you have any knowledge on twin cam heads witch im sure you just use you years of experience so just another set of heads anyway any information wouldn't go to wast i appreciate the time and effort you go through to make these vids for guys like myself to watch and learn from in many ways.
The "you don't need more than .600 lift" is a direct quote of another cam video I watched to see what was being said. I can't imagine it's coincidence.
Please do a video on opening and closing of the intake and exhaust! I’ve been reading that IVC is typical in range of 50-60* for better cylinder filling (of course you have to compensate your compression ratio for it too since it closes later) and typical exhaust valve closing is 5-10* for good exhaust scavenging (of course lots of cams are higher than that due to lsa) would be such a cool video
AWSOME content🦾😎 I was playing around with a piston velocity calculator a few weeks ago. Thinking about 500” Blown Fuel Hemi’s . Looking at a 4.5” stroke 7.017” Rod @8,200. I was looking at velocity’s as crank angle increased and I noticed maximum velocity was @ 74 degrees ADTC. I wrongly assumed it should of been in and out if 90🥸. Because cylinder pressure only starts to translate to rotational force on the crank around 15-20 degrees ATDC and the piston really starts to slow down so early around 80* ATDC. I started thinking about the ideal Ex valve opening event. As far as crank angle when it starts to move off the seat… for the crazy characteristics of Nitro🙏🏻. It’s like really really early. No wonder we move 5 gallons of fuel a second and make 10’ header flames. So I would love your take on a valve moving off the seat video. I really love information and knowledge. Most of the smartest guys in racing I know are very humble. The smarter one gets the less he thinks he knows because the finish line keeps getting farther away the faster we go. It’s the epitome of the saying “ you don’t know what you don’t know”🤦♂️
Excellent tutorial on cams! I have always relied on cam companies recommendations and they never really gave the best advice. I have to admit however, Bullet gave me a cam that made incredibly more power per same engine builds. The problem was it was not streetable.....for a street build.
I used a bronze gear on my Cleveland and it wore out pretty quick. i have a sintered iron gear i think and i check it periodically and its fine after 10 yrs on a comp roller hydraulic.
Nice points made here. Never looked at it as having more lift in the prime power making range. Good stuff. I've got a Hellcat and the cams usually make minimal gains and I think it is because of what you have said. They need more lift and less duration and be ground on a tighter angle. They are all wide and that usually results in weak low and midrange torque and even less top end if the motor likes the tighter grind such as a 108lsa or maybe conservative 110.
Hemi engines are a bit different because the valves can hit each other if the overlap is too much. Also hemi heads need different cam timing events because of how the exhaust can pull out intake charge easier.
According to David Vizard for sbc used 128 formula 128-C.I.D/8/Intake valve x.91. this formula is sbc V8 with 10.0:1-10.5:1 to find the optimal lsa for sbc v8
This is great info. Banks killing a Duramax represents the concept visually with the cam duration and lift overlayed with the flow curves. Interestingly enough, stock Duramax LMM lift exceeds head flow resulting in a flow curve that has the top cut off. Instead of a moment at X CFM it's holding X CFM for so many degrees of rotation. Much more air with the same duration. Especially when holding cylinder head max flow for a time. The flow curve almost looks like a square wave.
Many years ago and that was when I was like in my early 20s I had built a engine it was just a mix of parts that I came up with , heads of a g gas car , used billet steel roller isky cam . The engine ran ok and I called I think his name was T Willy and he told me I need about 20 deg less duration and could use more lift . One thing I did was try using different lash setting to change the way the engine ran . Of course there are limits .Thanks for the videos
You are making me wish I was younger to be able to play with the new equipment they have out there I am kidding I did pretty good with my cam choices and motor building. ☺️
Great video I learned alot is the second video out an also think u should do a rocker ratio video...I'm gonna watch this video a few times but great information
True on the turd cams. I remember drinking the GM kool aid with their factory hot rod cams for small blocks. Their cams were all about lots of duration and moderate lift. Was supposed to be for road racing. The engine just felt spongy. Changed out to an aftermarket cam. and the Z-28 came to life. The cam made all the difference...
Eric, you can say that higher lift gives you a flat top lobe. Meaning the head gets to peak flow faster and stays there literally flat across the lobe until lift goes below peak flow lift. In a flow graph which you should draw, makes it soooo much easier to explain, the flow duration graph will climb to peak and stay flat at peak flow for X duration. In the time flow is flat the lobe is lifting and coming over the nose and dropping until lift is below peak. Bam, flat top graph.
I'm really enjoying your vids, Eric. At 55 years of age I never tire of learning new things, especially about engines. I used to know a lot of "car math", able to quote formulas and such. I knew there was an art to cylinder heads and camshaft selection and often wondered how the guys at Comp would come up with their recommendations. It seems that they should've been asking more about low-to-mid lift flow numbers, instead of the box question..."What do the heads flow?". I knew the two were attached, but you just explained how. Keep 'em coming. BTW, I'm very interested in your next vid. I'm definitely curious about why the carb times were much faster than the EFI times. My hunch says it's related to CFM, specifically more is what that engine was begging for. 😛
Back when everybody was running ported 906 & 452 heads, a lot of pundits in the big block Mopar arena would always say that you don't need lift with a big inch mopar, because the intake ports "nose over" and quit gaining flow (or even lose flow) at a very modest lift level. But, the guys who ran super stock class drag engines commonly ran cams over .700" lift... *THEY* sure as hell weren't going to try to be competitive with a low lift cam
But they also didn't/don't care if it wiped out the springs/lifters, and valves. Winning was priority, not any meaningful reliability. Safe to say the majority of Eric's audience is street, some strip use or sportsman racing on a limited budget, so making max power is not the only criteria for valvetrain setup, they also need it to last a season or two of racing, or 15-25k on the street with only lash adjustment and normal maintenance.
@@thenewBH I don't remember if you could back in the 1970s and 1980s. I mean, now you can, but I'm not sure you could back in the day. The only guy I knew who ran superstock was in the 1990s, and we didn't talk about his cylinder heads much. I was under the impression that they were supposed to be limited in what was allowed..
The most lift and the correct overlap for the application is what I read in Vizard's books. He says duration is determined by the correct spec of LSA, LCA and something else I can't remember. But, once you have the correct numbers, duration is already locked in.
My favorite vid from you so far. We just say it different.......I say " less duration if you have good head flow " , you say more lift.....end product is the same.... shorter durations for the lift. I've had great luck with aggressive lift to duration ratios .
I am running 7.13 with a home built 406 with 220 Flotek CNC heads and a 292 schneider cam that everyone said was too small and would be a dog... 238/242@.050 at 108 with 622 lift and 11_1 people all think I have a solid cam from the sound. (Howards race HR lifters). I have spun it to 6800 and it still is pulling HARD and some day I'll set the 6al to 7k and see if I can get a better ET.
Wear on a brass distributor gear is dependent upon mechanical loading. If you have a high volume-high pressure oil pump expect a LOT more wear. You do not need a lot of oil pressure no more than 10 psi for every thousand increase in RPM up to a max of 60 psi (which will protect bearings even at 10,000 RPM. Secondly, a high volume oil pump is only required if you have a massive internal oil leak; such as the use of chamfered rod bearings that leak oil like a sieve. If you are really worried about wear you can buy a phenolic plastic distributor gears from Germany for a standard Chevy distributor (just not for a half inch diameter MSD distributor from the last time I looked). They wear like cast iron with no brass filings getting in the oil from a brass gear wearing away. Big Dave
yes using a Dynamic compression calcultor before you purchace off the shelf comp cams. Mine sounds great but is a pooch , the intake is 68 ABDC. and my compression is 10.2 mech. dynamically around 7.99
I try to get the most amount duration at 100 200 300 400 lift given mechanical limitations etc. Lobe selection is absolutely critical. It's also very application specific. A good road course camshaft is not always a good dragstrip camshaft.
I just bought a new cam for a boss 351 build. I had to choose between two good cams. I went with the one with a few less degrees @ .050 but had about .040 more lift overall. Lsa was 2 degrees wider but I'm told that should help with the huge boss ports. After this video, I feel I've probably made a good choice.
@@-Atrocious I went with a 110° lsa and 4 degrees advance. I built a Windsor years back and used a 106 and it loved it but the Cleveland is such a different animal.
Eric, you have shown us that some cylinder heads flow really good up to say .500 lift and no more. So it depends on other variables and be easy on the valve train.
Eric , I watched your video here . Can you cover “ time spent “ up the lobe and down the lobe “ and where the lifter spends most of the time vs motor piston cfm demand
E. I'm a new suber here, man I'm looking to upgrade my cam , what would be a effective choice as far as 411 gears , Maxx series promaxx heads which are sbc 183 /64 chamber btw I love the cylinder heads the company make best 1300 Ive spent tho the upgraded 411 posi was the most effective upgrade so far , and what do you know about Lunati cams? Or comp which would do good for my engine ?
Any way I think about it, I'll pretty much always circle back to agreeing with your first statement. The only response I have to it is I don't think people should be buying induction system parts on their combos for the SOLE PURPOSE of making up for and taking up the slack of other induction parts, because that's a recipe for not being satisfied with it's performance in the future.
And in an advertisement for the advantages of VVT on DOHC engines. where you can independently adjust the cam timing in software to gain maximum torque throughout the rev range. I don't know why so many people buy 'lockouts.' VVT is basically free power you're leaving on the table.
This is almost the same as the coyote vs ls debate. It's useful on small motors, but it makes smaller motors physically bigger and there is enough added complexity to make it less attractive than a larger motor. When you can put down more than you want to the point of detuning in lower gears, vvt can't really help you. I deleted the (single cam) vvt in my l92 due to valve clearance with an aftermarket cam. Its possible it could have given me 10-20 ft-lbs here or there but would have required larger valve relief's, at which point i could have just run more duration and a tighter LSA. Then there is the whole tuning it thing... Don't get me wrong, I'd love to mess around with vvt, it just doesn't give me anything on my motor.
Do you do camshaft recommendations? I am going to build sbc bracket racing engine. 406ci, 10.5:1 compression, AFR 210 Competition ported heads, supposedly flow 322cfm @.650 lift, super victor intake, solid lift roller camshaft. What cam specs would you recommend?
I have always seen for how much valve lift is based around the valve diameter and The valve seat angle the steeper the seat angle like 45-50° you would have more left almost half of the Valve diameter. If you’re running 25 to 30° you would run less lift.
We just dynoed our diesel pulling tractor engine. It put out right at 1200 hp and 2200 ft lbs torque but we only pulled it down to 2800 rpm and the torque was still climbing so it had more to go. I know you dont usually work on diesels but do you think more rocker ratio would make more power. They are only 1.6 ratio now.
Here's how I look at it, hope I can explain this. I look at the flow numbers on the head's, so say you have a set of head's (going to start around "mid lift") and from .300 to .400 you see let's just say 10 numbers increase in flow, then from .400 to .500 you see 6 numbers more flow, then from .500 to .600 you only see 2 numbers of gain in flow numbers. Then from .600 to .700 you really don't see much of a difference at all. So therefore a cam with around .500 lift will work the best with said head's, a bunch more lift isn't going to make the heads flow more air, so therefore no more power, the heads are maxed out around that .500 lift number. Did that make sense? I hope so!
The idea still works with late model stuff. I did that on my 6.0 LS, 1.7's to 1.8's. In terms of power it was noticeably quicker across the entire rev ranges, the only thing to watch out for is valvesprings. Even though I was well within the maximum lift spec of my springs, I still floated the valves and said goodbye to a bottom end and a cylinder head. 235/255 duration .620 lift to .665 lift, the springs were supposedly goot for .690
So if you have stock cams on a DOHC head, can you degree both your intake and your exhaust cams away from each other with more lobe separation for low end torque? In general?
Hey Eric I watch alot of your videos I have a big block 427 60 over so it's a 440 it's 10 to 1 compression I have a stock set of afr 265 oval port heads 219 intake 188 ex 100% cnc heads I have a howards hydraulic roller that is 235x241 duration @50 618 lift and a 108 lsa I have a victor Jr. Intake with a Holly 850 do you think this is a ok combo for the street and what type of horse power do you think it can make I was hoping for 525. What do you think?
I ran a combo really really close to that in a 4x4 79 3/4 ton pu w 4.10s , 4000 stall , 31 inch 10.50 tires as a daily driver . Horsepower ?? I dunno , but i had to pull it out because it was twisting the frame Bad , destroyed 3 turbo 400s , and twisted off the Detroit lockered corperate 14 bolt axles Regularily !!! Truck with me in it , through the exhaust , on street tires ran 13.10s @5800 lbs in 2WD . No traction . 4WD i broke shit and hard to steer spinning fronts . I could smoke the tires from a 70 mph roll . Your Rat will RUN but ive no idea on hp . Id say youve easily met your goal PLUS . Some may not believe it but i dont care . I also took your musclecars beer money on a regular basis . 🤣😂🤣 it was a Great street sleeper with Much better traction on concrete . 🤣😂🤣😎 Get your carb dialed in so you can frost the intake runners all the way to the heads on a warm engine at idle in summer and maintain that frost . I was quicker with a 750dp but that was probably a weight/gearing thing . 16 mpg wasnt all bad either on 93 pump gas for what it was in at 70mph . Anti-Reversion Cone Headers , long forgotton by many , Really bring the tight 108* LSA ALIVE on the Rat !!! Youll have to make the cones and tig them in . Good luck !!!
what do you think about procomp 195/62cc heads with a tfs1cam in a 9.1:1 stock bottom end Ford 302 and a 600 CFM carb? I think it might be too much head because surprisingly they are very very nice heads no casting flash no core shift 1.6 roller rockers RPM air gap intake seems to run okay but I'm still having some issues which I think is fuel or ignition related I want to change the carb I don't like the 1406 Edelbrock! runs great once it's up to temperature but I don't care how hot it is it needs to idle for at least 15 minutes before I can drive it but even then there's a loss of power between shifts I think it's the carb as soon as I let off the throttle to hit 2nd or 3rd it bogs and the plugs keep fouling like it's running way rich!
The old expression "the only cam with too much lift is the one you can't fit in the block" is largely true as you eluded to. The real reasons to not get more aggressive are as you mentioned, valve train parts life and the stability of the valve train its self. If you look at the undeniable success of lobes like the XE series it's because they go on the principles you talk about. For a set duration a higher intensity lobe will get you more lift and open the valves quicker making more power in most cases. It will also have a higher dynamic compression ratio which is critical if you're trying to do a budget build with a long block that has minimal work done to it e.g. maintaining a sub optimal compression ratio. Valve train money is almost always good money spent. The bottom end build up has three real jobs, not get destroyed, maintain seal to transfer energy and not lose power (different than making power) while the valve train and the heads are what actually allow you to produce power. I'm going with milder lobes on my build, I'd love more lift but I also have a perception of what I believe are of the mechanical limitations of the platform I'm working with valve train wise are. I'm talking a head that probably peaks out at .4 flow wise too,
How about Apr. 33% of the valvesize or test it in the flow bench to see where it ends to increase the flow? A smooth even custom profile with right amount of duration/ramps/lift in combination is probably the best way to go if you have no limitations. A cam is just one of many important parts in an engine.
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For the folks that might think this video is rudimentary in nature, remember who the target audience is.
People who are interested in hot rodding (and perhaps spending a few dollars) but who also have a lot of competing interests in their family budget…
Videos like this keep the interest up and keep the money flowing into the hobby and help all of us who provide some type of engine improvement service.
Keep up the good work Eric.
That is the purpose of cam tech lines.
Give a good recommendation for our HONEST input. 👍
I looked at cams differently once I made a cardioid equation for cams. You mentioned things that directly reflect what I got out of the situation. A main takeaway I got was the shape of the power curve. That made it easier to plan simpler builds that don't even rev higher than stock, but still run great. Life don't have to be so complicated.
Great introduction, I feel if people roled up their sleeves got to know how the numbers work make a few phone calls it would really help know what they are getting and know who's blowing smoke, great video
All of your videos are great.
Thank you for sharing all of this information. I’m never too old to learn, as a matter of fact, I’m always eager to learn more.
Keep them coming. You’ve got some of the best content here on RUclips. Thanks again for sharing 😉👍
thanks for sharing all the information with us I have learned alot from watching your channel I love all the detail you go into! I am a drag racer also and I am always trying to improve my engine performance you have helped me to understand how it all works to make a engine run better. thanks again!
I started studying cams after picking one for my motorcycle back in 2005. I wanted a good street engine and picked a cam advertised to meet my needs, I thought. The engine was a 4-cam Harley (Sportster) that I bored from 883 to 1250, courtesy of a 3-9/16” bore. The cam had 256° intake duration at 0.050” and 0.493” lift at the valve. With the heads I switched to, it made power at 6000, about 84 hp at the wheel, and flat torque curve between 4-5000 rpm. This was about double the original 883 power, but nothing like what others got from modified Sportsters.
Your point about lift is what I missed on that cam selection. A few years later, and after studying for a while, I went a totally different way on cams for my 103 Twin Cam, a Woods 222. With a 103° intake centerline, this has an intake closing of 34°, way shorter than that Sportster cam. I don’t remember the exact numbers for the “493” cam, but it was probably around 99° intake CL, or 47° IC ABDC. Typically an under square engine, smaller bore than stroke, is going to need more duration than one with more area, relatively, on top of the piston. The Twin Cam is bigger, 3.875x4.375 compared to 3.563x3.813, but the heads flow more and the lift is 0.575”, a lot more. Both are small bore engines.
The Twin Cam gets to 100 lb-ft of torque at the wheel at about 2500 rpm and stays there to 4500 or so, with a max of 104. The horsepower peak is around 5700. Overall it’s very strong for street riding for a 900 lb bike. Not a competition machine by any means!
So, you ask, what has that got to do with V8s? Based on my limited experience and some study, the significant numbers for cam selection are valve lift, intake closing (IC), and overlap. In this video, Eric mentioned 100° intake centerline on a cam with 240° intake duration, about 104° LSA, and almost 0.650” lift. Intake closing can be easily computed from duration and centerline as 240 divided by 2 plus centerline minus 180, or 240/2=120, 120+100=220, 220-180=40, which means IC is at 40° ABDC. If the new cam is installed 4° advanced as well, it’s intake centerline will be at 104, so 248/2=124, 124+104=228, and 228-180=48 for intake closing, substantially more. With another 0.100” or so of lift, this cam is going to make a lot more top end than the Engine Masters cam, which had a different purpose (and limitations).
Overlap is the other significant variable. It is also fairly simple to compute given duration at 0.050 for both intake and exhaust lobes and LSA. Intake opening BTDC is (for the old cam) 240/2=120, 120-100=20 and exhaust closing is 246/2=123, 123-108=15 ATDC, or 35° of overlap at 0.050” tappet lift. Note the LSA comes in as intake centerline is advanced from LSA (a lower number), exhaust centerline moves the other way (bigger number). The new cam, with a bit more LSA and longer duration computes as 248/2=124, 124-104=20 BTDC and 253/2=126.5, 126.5-112=14.5 ATDC, or nearly identical overlap to the earlier cam.
Eric has real world experience picking cams for himself and customers, and it sounds like he is way better than average at speccing them, despite his claims. The heart of any engine is based on heads, cam and intake (mostly effective runner length) performance. Watchers could do themselves a favor listening to him!
Eric, you have a great channel here, thanks!
So if you've got your intake and exhaust set up to work with a certain amount of overlap you don't want to mess with that when your making a cam change or if you do you would want to be aware of how much and if you're shifting it forward or backwards.
@@luckyPiston Most people quote intake duration and LSA to describe a cam. Brian Tooley said once that the valve events need to be what they need to be, or some words to that effect. Looking at his cams, I find that the overlap is often symmetrical, at least for LS engines. If you’re trying to get power out of the overlap event, that makes sense to me. The amount of overlap needed is generally a function of displacement vs cylinder head effectiveness, with bigger engines needing more. The more aggressive the cam (or the higher the rpm range), the more overlap as well. My motorcycle engines, being relatively small bore/long stroke, needed LOTS of overlap while the LS with its great breathing needs less. Overlap is bad for idle quality and somewhat for emissions, but makes a big difference in mid-range torque. That’s why Holdener’s cam comparisons sometimes show more torque through the entire rpm range he tests. Factory cams typically have none, thus the poor torque curve comparison. Eric seems to have figured the ideal amount of overlap for his engine and specced a cam that changed only the other end of each valve event.
Sorry for the windy reply…
@@bdugle1 No worries, Some good points there, interesting how a stroker likes more OL, my first thought is piston dwell time with the stroker is longer so why more OL and not less ? So what are your thoughts on dual pattern cams. I think they hurt power down low yet they are the predominant choice. Even when specing an engine that has plenty of exhaust flow people are still running dual pattern (in a street engine this makes no sense) my thought is with so many new heads on the market with improved exhaust you would think you would see more single pattern profiles. No one ever talks about how hot exhaust gas flows waaay better than what is in the cooler intake tract ? Density is enough of a factor that we have to correct for weather on our flow bench to get repeatability yet its never mentioned with gas exiting an engine.
@@luckyPiston I picked a cam for my 6.0 with strong street manners in mind, but I don’t claim to be an expert in selecting one for any combination. I have picked up a lot of general rules since starting to study cams in the last 15 or 20 years, however. I know a under-square engine is going to need more duration and more overlap, but picking precise numbers for a particular application for someone else is something I would not attempt.
As far as dual pattern cams-I think most applications seem to like them but single pattern cams can work well, too. The Comp 459 and 469 cams have the same intake lobe but the rec port cam (469) has more exhaust duration. The 459 is reported to have a better idle while the 469 has a slight edge at the top when compared in the same engine (from watching Holdener videos, basically). The SS2 cam has much shorter exhaust duration, near single pattern, and shows a strong torque curve all across the dyno graph. That supports your feeling that a single pattern cam has a place, even though it doesn’t make the top end of the bigger cams. If you’re running a 5.3 or 6.0 it could be a really good choice. I’d say especially if turbocharged.
I guess my rules would be get an expert’s recommendation on overlap, look for the highest lift you can get given the heads and valve train, and pick an intake closing point based on usage, displacement, and breathing limitations. Big BBCs need lots of duration while SBCs need moderate duration in the 355-383 size range. LSs need even less due to better stock heads. My Twin Cam bike cams intake close is at 34° which gives me a really strong low end. My LS cam has an intake valve closing of 42° which will run the power peak on a 6.0 out to low-to-mid 6000s. You undoubtedly have your own preferences for your engine.
I know a lot more now than when running a 301 and a 327 in a C Gas dragster back in the 60s. There’s still lots to learn though!
I think I’m from outer space but I do like reading and learning from these videos
Cool, I have been thinking along the same lines but you have cleared things up further. Cant wait for the next video.
Eric I feel that was your best video I've seen, I get the numbers. Thanks for sharing.
i love this video because im constantly saying "you cant afford any more". every time someone says they dont "need" more lift this is exactly why
Very informative!! Thanks for this! Really makes me rethink alot of my future builds.
Great information. Camshafts are a mystical and mythical thing to most people. What you have laid out here demonstrates the need for knowledgeable professional people to help in any project big or small.
Awesome. Keep up the good work.
Don't worry, we enjoy hearing your opinion about these things. Do as many videos as you wish for any subject that you wish to cover. We will tough it through them with a smile on our faces. Getting good knowledge and information is not easy to get so we like to hear all we can. Besides we also feel that you may know a thing more than we do. I know a lot but I don't know everything so I listen to everyone and separate the good from the bad. This is how you learn.
I enjoy your simplification of complicated topics.
I've learned more about cams in general than I have in yrs of guessing what there talking about
🔔😎😁 I was hoping for more explanation of why 600 lift works better for a head flow that tops out at 500 lift.
More area under the curve.
Thanks for your time and thoroughness.👍👍😎😎
David vizard has a method to select the proper camshaft instead of guessing, if anyone is interested.
What’s David’s method ?
@@michaelparadisis4076 128
I’m interested, where do I find info
@@shanehall7833 go to David vizard RUclips channel
Good video. I used to be a camshaft engineer for an OEM. We used an Adcole brand cam inspection machine but CMMs were coming onto the scene and able to do just about everything the specialized machine could do.
Thank you so so much for your videos. I made a comment on your other video before finding this one. What i now know in comparison to what i still have to learn about my 4.0 straight 6 for my jeep has told me a lot of how much i dont know. I want to build it to be a 4.6L with a small turbo to get to an easy 325 to 350 hp which is relatively considering very high end builds have kicked out 300hp naturally aspirated. I want my motor to of course have more power but also have good longevity.
I like the way u explain that more left concept.. I really get it
Eric!!!.. Excellent as ALWAYS!!. LOVED IT!!!... No such thing as too much for me!!.. I suck it up like sponge!!.. 55 years doing this!!. Always learning something new!!.
Thanks for watching
Good review of the key concepts, told in a way that those who may not be so "eye-balls deep" in this stuff will readily understand.
I will tell you this, nothing frustrates me more than calling a cam company wanting to have a technical conversation (along the lines Eric explained here) and instead it feeling like I just ran into a brick wall: no desire to talk tech, no ability to do so, and instead it appears to be primairly a SALES pitch they want to do!!!
Thanks Eric, good stuff...go deep on the techie stuff next!!!
Best cam video I’ve ever seen. We think alike. Don’t know how I missed this one I am a subscriber? Either way I am convinced you have a good head on your shoulders. Love profile is a major factor!
For visual people like me I think comparing the 2 lobes of lift vs duration would be easier to understand in a graph format. But this explained so much that I never truly understood in it's full context. It makes alot more sense now
I’m an Olds guy, I had a custom grind done for my current 455 build and kept an Olds friendly low lift spec. The heads were opened up to accept the “big” big block Olds valves along with some basic cleanup in the bowls and runners. I kept the lift low because the heads just don’t flow much above .500 so it seemed like needless stress (and expense) on the valvetrain. But I’m sure the quality of builds your doing far, far exceed the dinosaurs I’m messing around with. Great video, certainly quality food for thought.
W-30 cam is a goood street cam
Awesome content!
Good Job..... You just confirmed what I was doing 2.5 plus decades ago.....
Cheers for shearing your knowledge im about to set to clean up my Harley heads at this stage casting imperfections ive not done much in this kind of thing before but i cant stop watching your vids if you have any knowledge on twin cam heads witch im sure you just use you years of experience so just another set of heads anyway any information wouldn't go to wast i appreciate the time and effort you go through to make these vids for guys like myself to watch and learn from in many ways.
Excellent video. Thank you.
The "you don't need more than .600 lift" is a direct quote of another cam video I watched to see what was being said. I can't imagine it's coincidence.
Lol 😂
Please do a video on opening and closing of the intake and exhaust! I’ve been reading that IVC is typical in range of 50-60* for better cylinder filling (of course you have to compensate your compression ratio for it too since it closes later) and typical exhaust valve closing is 5-10* for good exhaust scavenging (of course lots of cams are higher than that due to lsa) would be such a cool video
AWSOME content🦾😎 I was playing around with a piston velocity calculator a few weeks ago. Thinking about 500” Blown Fuel Hemi’s . Looking at a 4.5” stroke 7.017” Rod @8,200. I was looking at velocity’s as crank angle increased and I noticed maximum velocity was @ 74 degrees ADTC. I wrongly assumed it should of been in and out if 90🥸. Because cylinder pressure only starts to translate to rotational force on the crank around 15-20 degrees ATDC and the piston really starts to slow down so early around 80* ATDC. I started thinking about the ideal Ex valve opening event. As far as crank angle when it starts to move off the seat… for the crazy characteristics of Nitro🙏🏻. It’s like really really early. No wonder we move 5 gallons of fuel a second and make 10’ header flames. So I would love your take on a valve moving off the seat video. I really love information and knowledge. Most of the smartest guys in racing I know are very humble. The smarter one gets the less he thinks he knows because the finish line keeps getting farther away the faster we go. It’s the epitome of the saying “ you don’t know what you don’t know”🤦♂️
Great informtion ; helps to make sense of the camshaft debate.
Great video. It was well worth the time watching it.
Thanks
Excellent tutorial on cams! I have always relied on cam companies recommendations and they never really gave the best advice. I have to admit however, Bullet gave me a cam that made incredibly more power per same engine builds. The problem was it was not streetable.....for a street build.
I used a bronze gear on my Cleveland and it wore out pretty quick. i have a sintered iron gear i think and i check it periodically and its fine after 10 yrs on a comp roller hydraulic.
Those comp bushed shaft rockers for LS are great. Seen a few guys now up near .700 on them.
excellent video. I didn't know I could run more lift if my lsa was higher.
Nice points made here. Never looked at it as having more lift in the prime power making range. Good stuff. I've got a Hellcat and the cams usually make minimal gains and I think it is because of what you have said. They need more lift and less duration and be ground on a tighter angle. They are all wide and that usually results in weak low and midrange torque and even less top end if the motor likes the tighter grind such as a 108lsa or maybe conservative 110.
Hemi engines are a bit different because the valves can hit each other if the overlap is too much. Also hemi heads need different cam timing events because of how the exhaust can pull out intake charge easier.
According to David Vizard for sbc used 128 formula 128-C.I.D/8/Intake valve x.91. this formula is sbc V8 with 10.0:1-10.5:1 to find the optimal lsa for sbc v8
This is great info. Banks killing a Duramax represents the concept visually with the cam duration and lift overlayed with the flow curves. Interestingly enough, stock Duramax LMM lift exceeds head flow resulting in a flow curve that has the top cut off. Instead of a moment at X CFM it's holding X CFM for so many degrees of rotation. Much more air with the same duration. Especially when holding cylinder head max flow for a time. The flow curve almost looks like a square wave.
Great information
Many years ago and that was when I was like in my early 20s I had built a engine it was just a mix of parts that I came up with , heads of a g gas car , used billet steel roller isky cam . The engine ran ok and I called I think his name was T Willy and he told me I need about 20 deg less duration and could use more lift . One thing I did was try using different lash setting to change the way the engine ran . Of course there are limits .Thanks for the videos
Learned a lot this time !
Well done Eric.
Thank you.
Excellent explanation
Thanks for watching.
You are making me wish I was younger to be able to play with the new equipment they have out there I am kidding I did pretty good with my cam choices and motor building. ☺️
I've learned a lot wow what a class.
I'd love to hear the valve events, you won't lose everyone in here
Awesome video. Thanks
Run a Monel gear on the distributor, and never worry about it.
And on a further note, i would watch a 4hr video from you on camshafts.
Great video I learned alot is the second video out an also think u should do a rocker ratio video...I'm gonna watch this video a few times but great information
Thanks for watching.
great video
Very informative 👍
I bet a lot of gearheads felt this video to be too shot! I really enjoyed it and gained a little knowledge as well.
True on the turd cams. I remember drinking the GM kool aid with their factory hot rod cams for small blocks. Their cams were all about lots of duration and moderate lift. Was supposed to be for road racing. The engine just felt spongy. Changed out to an aftermarket cam. and the Z-28 came to life. The cam made all the difference...
Eric, you can say that higher lift gives you a flat top lobe. Meaning the head gets to peak flow faster and stays there literally flat across the lobe until lift goes below peak flow lift. In a flow graph which you should draw, makes it soooo much easier to explain, the flow duration graph will climb to peak and stay flat at peak flow for X duration. In the time flow is flat the lobe is lifting and coming over the nose and dropping until lift is below peak. Bam, flat top graph.
I'm really enjoying your vids, Eric. At 55 years of age I never tire of learning new things, especially about engines. I used to know a lot of "car math", able to quote formulas and such. I knew there was an art to cylinder heads and camshaft selection and often wondered how the guys at Comp would come up with their recommendations. It seems that they should've been asking more about low-to-mid lift flow numbers, instead of the box question..."What do the heads flow?". I knew the two were attached, but you just explained how. Keep 'em coming. BTW, I'm very interested in your next vid. I'm definitely curious about why the carb times were much faster than the EFI times. My hunch says it's related to CFM, specifically more is what that engine was begging for. 😛
Back when everybody was running ported 906 & 452 heads, a lot of pundits in the big block Mopar arena would always say that you don't need lift with a big inch mopar, because the intake ports "nose over" and quit gaining flow (or even lose flow) at a very modest lift level.
But, the guys who ran super stock class drag engines commonly ran cams over .700" lift... *THEY* sure as hell weren't going to try to be competitive with a low lift cam
To be fair, you can port, weld, and epoxy SS heads...
But they also didn't/don't care if it wiped out the springs/lifters, and valves. Winning was priority, not any meaningful reliability. Safe to say the majority of Eric's audience is street, some strip use or sportsman racing on a limited budget, so making max power is not the only criteria for valvetrain setup, they also need it to last a season or two of racing, or 15-25k on the street with only lash adjustment and normal maintenance.
@@thenewBH I don't remember if you could back in the 1970s and 1980s.
I mean, now you can, but I'm not sure you could back in the day.
The only guy I knew who ran superstock was in the 1990s, and we didn't talk about his cylinder heads much. I was under the impression that they were supposed to be limited in what was allowed..
Finally someone who gets it. Lift, lift, lift... Lift is EVERYTHING!
The most lift and the correct overlap for the application is what I read in Vizard's books. He says duration is determined by the correct spec of LSA, LCA and something else I can't remember. But, once you have the correct numbers, duration is already locked in.
Can you do an in depth video on the valve events and what they effect. I’ve got a general idea but would like to learn more
Thanks for video!
Maximum piston speed is usually around 75 to 77 degrees sfter tdc & this also will be in the midlife range of the flow curve.
Your camero cam grind builds cylinder pressure also because no scavenger lift in it. I feel like a kid again brother 🥂🏁
Especially with closed chamber heads. Need a lot of lift to unshroud the valves.
Interesting Great video 👍👍🙏🙏
My favorite vid from you so far. We just say it different.......I say " less duration if you have good head flow " , you say more lift.....end product is the same.... shorter durations for the lift. I've had great luck with aggressive lift to duration ratios .
I am running 7.13 with a home built 406 with 220 Flotek CNC heads and a 292 schneider cam that everyone said was too small and would be a dog... 238/242@.050 at 108 with 622 lift and 11_1 people all think I have a solid cam from the sound. (Howards race HR lifters). I have spun it to 6800 and it still is pulling HARD and some day I'll set the 6al to 7k and see if I can get a better ET.
Wear on a brass distributor gear is dependent upon mechanical loading. If you have a high volume-high pressure oil pump expect a LOT more wear. You do not need a lot of oil pressure no more than 10 psi for every thousand increase in RPM up to a max of 60 psi (which will protect bearings even at 10,000 RPM. Secondly, a high volume oil pump is only required if you have a massive internal oil leak; such as the use of chamfered rod bearings that leak oil like a sieve.
If you are really worried about wear you can buy a phenolic plastic distributor gears from Germany for a standard Chevy distributor (just not for a half inch diameter MSD distributor from the last time I looked). They wear like cast iron with no brass filings getting in the oil from a brass gear wearing away.
Big Dave
yes using a Dynamic compression calcultor before you purchace off the shelf comp cams. Mine sounds great but is a pooch , the intake is 68 ABDC. and my compression is 10.2 mech. dynamically around 7.99
I try to get the most amount duration at 100 200 300 400 lift given mechanical limitations etc. Lobe selection is absolutely critical. It's also very application specific. A good road course camshaft is not always a good dragstrip camshaft.
You said it-most guys shy from lift is valve train stress (especially street)
I just bought a new cam for a boss 351 build. I had to choose between two good cams. I went with the one with a few less degrees @ .050 but had about .040 more lift overall. Lsa was 2 degrees wider but I'm told that should help with the huge boss ports. After this video, I feel I've probably made a good choice.
👍
What lsa did you end up with just curious?
@@-Atrocious I went with a 110° lsa and 4 degrees advance. I built a Windsor years back and used a 106 and it loved it but the Cleveland is such a different animal.
Eric, you have shown us that some cylinder heads flow really good up to say .500 lift and no more. So it depends on other variables and be easy on the valve train.
Even if it flows only to .500 the valve will spend more time there with .600 lift cam than a .500 lift cam.
Is the lobe area calculated on Adv or @0.05? the intake lobe on the new cam is a lot softer than teh ex of the old cam.
I always felt & saw , better tourque in "Lift" saves time filling jugs❣️
Definitely salesmen are salesman I want what works in the real world I'm a numbers kind of guy I know we've all heard this but knowledge is power
Eric , I watched your video here . Can you cover “ time spent “ up the lobe and down the lobe “ and where the lifter spends most of the time vs motor piston cfm demand
E. I'm a new suber here, man I'm looking to upgrade my cam , what would be a effective choice as far as 411 gears , Maxx series promaxx heads which are sbc 183 /64 chamber btw I love the cylinder heads the company make best 1300 Ive spent tho the upgraded 411 posi was the most effective upgrade so far , and what do you know about Lunati cams? Or comp which would do good for my engine ?
Any way I think about it, I'll pretty much always circle back to agreeing with your first statement. The only response I have to it is I don't think people should be buying induction system parts on their combos for the SOLE PURPOSE of making up for and taking up the slack of other induction parts, because that's a recipe for not being satisfied with it's performance in the future.
I always and I mean ALWAYS! Go with what Cam Shaft/Spec my Porter Recommends with their heads after explaining to them my goals.
Amen brother, went to a hotrod hangout a while back , sounded like a herd of turds. Just shook my head and left.
And in an advertisement for the advantages of VVT on DOHC engines. where you can independently adjust the cam timing in software to gain maximum torque throughout the rev range.
I don't know why so many people buy 'lockouts.' VVT is basically free power you're leaving on the table.
This is almost the same as the coyote vs ls debate. It's useful on small motors, but it makes smaller motors physically bigger and there is enough added complexity to make it less attractive than a larger motor. When you can put down more than you want to the point of detuning in lower gears, vvt can't really help you. I deleted the (single cam) vvt in my l92 due to valve clearance with an aftermarket cam. Its possible it could have given me 10-20 ft-lbs here or there but would have required larger valve relief's, at which point i could have just run more duration and a tighter LSA. Then there is the whole tuning it thing... Don't get me wrong, I'd love to mess around with vvt, it just doesn't give me anything on my motor.
I'm with ya. Would you agree it's only as good as your head flows? After a certain lift with low performance heads won't it become parasitic?
Maybe a chalk board so you can use a diagram drawing would help. More to relate to.
You also add velocity to the opening of the valve
That's pretty much implied don't you think?
Do you do camshaft recommendations? I am going to build sbc bracket racing engine. 406ci, 10.5:1 compression, AFR 210 Competition ported heads, supposedly flow 322cfm @.650 lift, super victor intake, solid lift roller camshaft. What cam specs would you recommend?
Please keep talking.. or do as many videos as you wish.. very informative..👍
I have always seen for how much valve lift is based around the valve diameter and The valve seat angle the steeper the seat angle like 45-50° you would have more left almost half of the Valve diameter. If you’re running 25 to 30° you would run less lift.
We just dynoed our diesel pulling tractor engine. It put out right at 1200 hp and 2200 ft lbs torque but we only pulled it down to 2800 rpm and the torque was still climbing so it had more to go. I know you dont usually work on diesels but do you think more rocker ratio would make more power. They are only 1.6 ratio now.
Here's how I look at it, hope I can explain this.
I look at the flow numbers on the head's, so say you have a set of head's (going to start around "mid lift") and from .300 to .400 you see let's just say 10 numbers increase in flow, then from .400 to .500 you see 6 numbers more flow, then from .500 to .600 you only see 2 numbers of gain in flow numbers.
Then from .600 to .700 you really don't see much of a difference at all.
So therefore a cam with around .500 lift will work the best with said head's, a bunch more lift isn't going to make the heads flow more air, so therefore no more power, the heads are maxed out around that .500 lift number.
Did that make sense? I hope so!
Like Eric said. It will give you more time at your max flow. Even at well past .500 lift. It gives you more flow at your low flow numbers also...
More lift was the norm back in the 50's when they went to 1.6 from 1.5 rockers on small block chevys.
It's still the norm.
The idea still works with late model stuff. I did that on my 6.0 LS, 1.7's to 1.8's. In terms of power it was noticeably quicker across the entire rev ranges, the only thing to watch out for is valvesprings. Even though I was well within the maximum lift spec of my springs, I still floated the valves and said goodbye to a bottom end and a cylinder head. 235/255 duration .620 lift to .665 lift, the springs were supposedly goot for .690
With using a stronger spring for more lift, does this not take more power from the crank/cam to compress in general?
So if you have stock cams on a DOHC head, can you degree both your intake and your exhaust cams away from each other with more lobe separation for low end torque? In general?
So you can spec out a cam on the 60 over hot street 292 inline chewy six I'm building?
Hey Eric I watch alot of your videos I have a big block 427 60 over so it's a 440 it's 10 to 1 compression I have a stock set of afr 265 oval port heads 219 intake 188 ex 100% cnc heads I have a howards hydraulic roller that is 235x241 duration @50 618 lift and a 108 lsa I have a victor Jr. Intake with a Holly 850 do you think this is a ok combo for the street and what type of horse power do you think it can make I was hoping for 525. What do you think?
I ran a combo really really close to that in a 4x4 79 3/4 ton pu w 4.10s , 4000 stall , 31 inch 10.50 tires as a daily driver . Horsepower ?? I dunno , but i had to pull it out because it was twisting the frame Bad , destroyed 3 turbo 400s , and twisted off the Detroit lockered corperate 14 bolt axles Regularily !!! Truck with me in it , through the exhaust , on street tires ran 13.10s @5800 lbs in 2WD . No traction . 4WD i broke shit and hard to steer spinning fronts .
I could smoke the tires from a 70 mph roll . Your Rat will RUN but ive no idea on hp . Id say youve easily met your goal PLUS . Some may not believe it but i dont care . I also took your musclecars beer money on a regular basis . 🤣😂🤣 it was a Great street sleeper with Much better traction on concrete . 🤣😂🤣😎
Get your carb dialed in so you can frost the intake runners all the way to the heads on a warm engine at idle in summer and maintain that frost . I was quicker with a 750dp but that was probably a weight/gearing thing . 16 mpg wasnt all bad either on 93 pump gas for what it was in at 70mph . Anti-Reversion Cone Headers , long forgotton by many , Really bring the tight 108* LSA ALIVE on the Rat !!! Youll have to make the cones and tig them in .
Good luck !!!
what do you think about procomp 195/62cc heads with a tfs1cam in a 9.1:1 stock bottom end Ford 302 and a 600 CFM carb? I think it might be too much head because surprisingly they are very very nice heads no casting flash no core shift 1.6 roller rockers RPM air gap intake seems to run okay but I'm still having some issues which I think is fuel or ignition related I want to change the carb I don't like the 1406 Edelbrock! runs great once it's up to temperature but I don't care how hot it is it needs to idle for at least 15 minutes before I can drive it but even then there's a loss of power between shifts I think it's the carb as soon as I let off the throttle to hit 2nd or 3rd it bogs and the plugs keep fouling like it's running way rich!
Procomp heads are usually junk.
The old expression "the only cam with too much lift is the one you can't fit in the block" is largely true as you eluded to. The real reasons to not get more aggressive are as you mentioned, valve train parts life and the stability of the valve train its self.
If you look at the undeniable success of lobes like the XE series it's because they go on the principles you talk about. For a set duration a higher intensity lobe will get you more lift and open the valves quicker making more power in most cases. It will also have a higher dynamic compression ratio which is critical if you're trying to do a budget build with a long block that has minimal work done to it e.g. maintaining a sub optimal compression ratio.
Valve train money is almost always good money spent. The bottom end build up has three real jobs, not get destroyed, maintain seal to transfer energy and not lose power (different than making power) while the valve train and the heads are what actually allow you to produce power.
I'm going with milder lobes on my build, I'd love more lift but I also have a perception of what I believe are of the mechanical limitations of the platform I'm working with valve train wise are. I'm talking a head that probably peaks out at .4 flow wise too,
WOW. Thanks
How about Apr. 33% of the valvesize or test it in the flow bench to see where it ends to increase the flow? A smooth even custom profile with right amount of duration/ramps/lift in combination is probably the best way to go if you have no limitations. A cam is just one of many important parts in an engine.
I have a question with boost. lift isn’t as important since air is being pushed in instead of sucked in like NA so NA lift would be more crucial?