When I was about 21 I built a big block for my 1970 Chevelle. I installed a Crower solid lift with radical lift and 105 degree lobe separation. Piss poor vacuum and very lopey idle. It hauled down the track and pulled like a freight train from 3500-6500 rpm. After having a family nice Sunday drives were a pain because of the way it ran. So it got mothballed until recently when my 20 year old pulled it out because of the stories everyone told about it. Well, it’s like starting over. So many years in storage has taken its toll.
My friend's dad who is a mechanic said cars will break just by sitting. I find that to be true. At least keep it running and rolling if nothing else to shake the rat turds out.
We'll sort of, the tighter the LSA the quicker valve events happen. You can have 2 identical duration and lift cams with one being a 113lsa and one a 108lsa, the 108 will sound more rowdy because everything is happening faster and more often. A tighter LSA cam will provide more low end while a wider LSA more top end, this is why you'll see boosted cars running a bit wider LSA. If you want more in depth cam explanation look up David Vizard on RUclips, particularly his 128 method, he is a wealth of knowledge.
That assumes more overlap based on keeping the same duration. But, more than one way to skin a cat: higher lift with shorter duration can get the same [or maybe more] pounds/hour air in, while holding overlap at the same value.
Every time someone talks about lobe separation angle, they cant help but talk about overlap. And its true, it does increase, but the tighter it is , the better it is for the most important of the four opening and closing points of the cam. The tighter the LSA, the sooner the intake valve closes, making more cyl. pressure. Also There is a difference between more duration at .050 overlap and overlap created by a tight lsa.
Weingartner just wrapped up an LS3 cam challenge with some very serious submissions - over 20 cams. Numbers on winner are not yet out, but check out his channel. But to your point, if goal is low end torque, less overlap is your friend. An lsa that works? keep it, and go for less duration.
What Powerblock didn't dicuss you look for wider overlap cams 112 to 114 for engines that have large valves like a chevy 350, and a low overlap cam 110 to 108 LCAfor a 305 chevy or a 400 where the valve aren't large enough.
Actually the 305 always had big valves and small combustion chambers. Some 350s, mostly truck engines had small valves. Majority of the SBC heads had 1.94 intake valves.
No... that radius trick buys area under the curve for limited lift, but the exact same duration applies. If you want more duration, you get into reducing base circle [modifying an existing cam]
There's always overlap. Always. The point of reference is missing there: 0.050" valve events, which is roughly where flow is even worth considering measuring. For symmetrical lobes, some easy math: add advertised durations of intake and exhaust. Divide that result by 4. Subtract the LSA from that, and multiply the remainder by 2 --- theres your real overlap, and it usually matches 0.006" lift events as ground.
LSA doesn't determine overlap. Overlap determines overlap. You can have a cam on 112° LSA and 60° of overlap, and you can have a 106° LSA with 60° overlap. The LSA determines if the engine will make maximum output, and overlap determines where in the power curve output will peak. Duration and lift are byproducts of choosing LSA and overlap. So many get this wrong.
That pretty much matches my thinking. I choose overlap to best serve the desired application rpm, and lsa has to find the sweet spot for best volumetric efficiency & scavenging. The first is a time management tool, the second deals with [na build] fixed factors: heads, exhaust, etc. Turbo guys have the luxury [sometimes a headache] of a variable precharge curve that takes atmospheric pressure off the table - air density/temp get the focus instead.
@@kermets I like to think of it as clocking volume, mostly: it takes bore, stroke, and valve size into account as primary factors. Air is lazy. Add fuel in suspension it gets worse. Basically, the larger amount of air to be managed per cycle, the greater the sloth and to motivate that... means applying a shorter LSA [tweaking overlap] for a stronger signal. But only to a point - too tight gives away top end power. Finding the sweet spot is like hitting a tuning fork just right - it sings.
I remember Hot Rod Magazine did a blower motor build where they used a Comp Cams with a 110 degree LSA.....Why Why Why would you do something like that? Blower motors need a higher LSA like in the 113 -116 range. Hot Rod Magazine even has a test, with results shown online, that boosted engines need that wider LSA (see Hot Rod Magazine Camshaft Shootout: Lobe-Separation Angle Tested and Explained Notice: This is not a comment about Blower cams, nor their lift and duration.... It is a comment about LSA and it's scavenging effect @ on NA motors compared to SC motors. Both valves open at the same time on a SC motor creates a boost leak, and you don't want that. But at the same time, Higher LSA does not make a cam a "Blower Cam." Comp Camps sells camshafts for NA Coyote engines that have up to 130 LSA
Why? That would be duration driven. A basic 262 cam with a 110 lsa has 42 degrees overlap. To hold overlap the same on a 272 cam spreads lsa to 115 degrees. On a 282 cam lsa gets pushed to 120 degrees to keep that same 42 degrees.
When I was about 21 I built a big block for my 1970 Chevelle. I installed a Crower solid lift with radical lift and 105 degree lobe separation. Piss poor vacuum and very lopey idle. It hauled down the track and pulled like a freight train from 3500-6500 rpm. After having a family nice Sunday drives were a pain because of the way it ran. So it got mothballed until recently when my 20 year old pulled it out because of the stories everyone told about it. Well, it’s like starting over. So many years in storage has taken its toll.
How’s the rebuild going?
@@user-manny43Also curious 👀👀
My friend's dad who is a mechanic said cars will break just by sitting. I find that to be true. At least keep it running and rolling if nothing else to shake the rat turds out.
Thanks for a simple answer. I just watched a 17-minute video on this and still had no idea what it was.
So the less lobe separation the more chop ?
We'll sort of, the tighter the LSA the quicker valve events happen. You can have 2 identical duration and lift cams with one being a 113lsa and one a 108lsa, the 108 will sound more rowdy because everything is happening faster and more often. A tighter LSA cam will provide more low end while a wider LSA more top end, this is why you'll see boosted cars running a bit wider LSA. If you want more in depth cam explanation look up David Vizard on RUclips, particularly his 128 method, he is a wealth of knowledge.
That assumes more overlap based on keeping the same duration. But, more than one way to skin a cat: higher lift with shorter duration can get the same [or maybe more] pounds/hour air in, while holding overlap at the same value.
Every time someone talks about lobe separation angle, they cant help but talk about overlap. And its true, it does increase, but the tighter it is , the better it is for the most important of the four opening and closing points of the cam. The tighter the LSA, the sooner the intake valve closes, making more cyl. pressure. Also There is a difference between more duration at .050 overlap and overlap created by a tight lsa.
Need more info ls3 no boost application.
What would give better low end turque lsa low or high?
Weingartner just wrapped up an LS3 cam challenge with some very serious submissions - over 20 cams. Numbers on winner are not yet out, but check out his channel. But to your point, if goal is low end torque, less overlap is your friend. An lsa that works? keep it, and go for less duration.
What Powerblock didn't dicuss you look for wider overlap cams 112 to 114 for engines that have large valves like a chevy 350, and a low overlap cam 110 to 108 LCAfor a 305 chevy or a 400 where the valve aren't large enough.
Actually the 305 always had big valves and small combustion chambers. Some 350s, mostly truck engines had small valves. Majority of the SBC heads had 1.94 intake valves.
hey got a question for you ..do a elgin e-1090p cam have a nice chock sound to it.
You can increase the duration by flattening the top of the Loeb there for the valve stays open for a longer duration
No... that radius trick buys area under the curve for limited lift, but the exact same duration applies. If you want more duration, you get into reducing base circle [modifying an existing cam]
@@flinch622glad to see someone understands cams.
I am looking for cam for a 1969 Cougar eliminator 428 scj. I need good vacuum for power braked and head light doors. Any help?
Engine volume controller = lobe sep
What is icl
Intake Centre Line.
What's the best LSA for best torque?
107
Narrow
I just don't understand, if there's no overlap, how are you going to scavenge exhaust gases?
There's always overlap. Always. The point of reference is missing there: 0.050" valve events, which is roughly where flow is even worth considering measuring. For symmetrical lobes, some easy math: add advertised durations of intake and exhaust. Divide that result by 4. Subtract the LSA from that, and multiply the remainder by 2 --- theres your real overlap, and it usually matches 0.006" lift events as ground.
LSA doesn't determine overlap. Overlap determines overlap.
You can have a cam on 112° LSA and 60° of overlap, and you can have a 106° LSA with 60° overlap.
The LSA determines if the engine will make maximum output, and overlap determines where in the power curve output will peak.
Duration and lift are byproducts of choosing LSA and overlap. So many get this wrong.
That pretty much matches my thinking. I choose overlap to best serve the desired application rpm, and lsa has to find the sweet spot for best volumetric efficiency & scavenging. The first is a time management tool, the second deals with [na build] fixed factors: heads, exhaust, etc. Turbo guys have the luxury [sometimes a headache] of a variable precharge curve that takes atmospheric pressure off the table - air density/temp get the focus instead.
No info
Said a whole lot and didn't answer anything
supercharged6771 like every single cam video
Check out vintageiron channel. I can't Rem the exact channel name, but he has several cam vids. Best out there.
Yep ......they told us everything BUT what lobe separation Does ? still in the dark....
@@kermets I like to think of it as clocking volume, mostly: it takes bore, stroke, and valve size into account as primary factors. Air is lazy. Add fuel in suspension it gets worse. Basically, the larger amount of air to be managed per cycle, the greater the sloth and to motivate that... means applying a shorter LSA [tweaking overlap] for a stronger signal. But only to a point - too tight gives away top end power. Finding the sweet spot is like hitting a tuning fork just right - it sings.
Lobe sep = is basically a volume controller for an engine
Well hellloooo beard
I remember Hot Rod Magazine did a blower motor build where they used a Comp Cams with a 110 degree LSA.....Why Why Why would you do something like that? Blower motors need a higher LSA like in the 113 -116 range. Hot Rod Magazine even has a test, with results shown online, that boosted engines need that wider LSA (see Hot Rod Magazine Camshaft Shootout: Lobe-Separation Angle Tested and Explained
Notice: This is not a comment about Blower cams, nor their lift and duration.... It is a comment about LSA and it's scavenging effect @ on NA motors compared to SC motors. Both valves open at the same time on a SC motor creates a boost leak, and you don't want that. But at the same time, Higher LSA does not make a cam a "Blower Cam." Comp Camps sells camshafts for NA Coyote engines that have up to 130 LSA
Why? That would be duration driven. A basic 262 cam with a 110 lsa has 42 degrees overlap. To hold overlap the same on a 272 cam spreads lsa to 115 degrees. On a 282 cam lsa gets pushed to 120 degrees to keep that same 42 degrees.