Avoid Failure! Camshaft And Lifter Wear Patterns - What They Mean And How They Are Established
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- Опубликовано: 14 окт 2024
- Lobe taper, lifter crown, valve train weight and oil distribution all contribute to the unique wear pattern that mates all solid and hydraulic flat tappets to their respective cam lobes.
Here's a rundown of the various forces at work, and how you can visually read a cam to make sure it's break-in went well, and it will live a long, healthy life.
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As the elder Boomers are aging out and the youngsters are moving in you should do videos like this. How to READ stuff, bearings, gears, etc... and those of us still invested in HotRodding love the content as well.
His stuff is so easy to watch. As someone who was out of the hobby for a time for reasons, it’s like the easiest to understand refresher courses I’ve ever had. He keeps his explanations simple and backs up most of what he shows with physical examples of the how and why.
426 hemi/440RB's are actually off set by about 1/16' back ( on top of original usage of a crowning on the lifter's ) on the cam vs lifter's i know because i measured it for my roller viper-cam style im using
I work at a high school technical center. Your information is perfect for the kids to comprehend. Also, just short enough to keep their attention. You make everything very easy to understand. I’m in my mid 50’s and grew up with all of what you are teaching. I especially like that everything you teach is universal. I’m a Buick guy and I have thought back for several years now.. “ hmm what did Tony say”.. thanks for your time man.
Ever thought about missing oil thrower paddles on aftermarket conrods? Original GM Small Block rods have so called Splashers that throw oil on the cam lobes, most aftermarket rods dont have these oil throwers
More than 40 years ago I bought a 68 Chevy truck from a garage that acquired it with a mechanics lean. What happened was they put in a used engine supplied by the owner and it ran like crap. They told him the cam was bad and what it would cost to replace it. The owner didn't want to put that kind of money into a 15 year old truck but also refused to pay for the work already done. I bought it by paying off the amount owed thinking I was going to need to replace the engine. My father in law owned a garage. When we checked about 4 lifters had no tension against the rocker, "very early Chevy 350" But my father in law noticed that when the engine turned over the push rod moved as much as ones that seemed normal almost like the pushrods were too short.. Pulled and measured, all the same length, started pulling lifters. All were fine except the 4 in question had wore clear through to the hydraulic center. My father in law ordered another set of lifters. We dropped them in adjusted the lifters and the engine ran fine. No smoke no noise. I ran it for another 12 years and sold it for a lot more than it cost me to buy it.
Don't care if you got another 12 years out of it. You do not put new lifters on a used cam. Period.
@@daveo532 New lifters are put on used cams all the time. All you do is act like a new cam break in.. Run the engine at about 2500 for half an hour an very the speed up or down 200 rpm. If there would have been a problem it would have showed up. It was not a high performance engine so the valve springs tension was not very high and we readjusted the valves after break in. We put other used cams in without problems. I put a used cam with higher lift in my 289 mustang motor out of a 351. There wasn't any problem. Just had to change the firing order.
Change lifters all the time. No biggie.
@@daveo532 I think you got it backwards buddy you never put used lifters on a new cam..
I thought I knew a fair bit about cams and lifters, and their operational dynamics, but man oh man, there's a lot of good info here that I'd never even considered. Thanks for the great lecture, Tony, you are a true master.
I'm 65 almost 6. I used to wrench on my vehicles out in the backyard all the time back in the 70's. Mom told me once she asked dad to go out and help me (WW2 military mechanic) she said that's how he learned. 40 something years later, thanks uncle Tony ! Very informative.
I raced 340 Super Stock in the 70's. I knew about the cam taper but not about lobes being ground to cancel out the thrust. Thanks for teaching a old racer something new!😀
Good Stuff! I've been building motors for over 30+ Years and actually learned something I didn't know...The reversed tapers on a properly ground "A series" MOPAR motor. Myself, I build GM motors these days, specifically Z/28 302/LT-1 motors. The last LT-1 I built I wanted it to "run a little better" than OEM, called up Bullet Cams and ordered a couple of UltraDyne solid flat tappet lobes I always liked. The OEM GM solid lifter came in 2 types, the "piddle valve" and "edge orifice" type that cuts top end oiling by about 15-20%...Fun Fact the majority of late 60's solid lifter HP motors had the "585" series edge orifice in them. I was running roller rockers and didn't need the full oiling. The OEM GM lifters have a stellite hard face on them, they are far better than anything else ouside of a tool steel lifter and the best for long term street reliability... the last time they were sold through Gm they ran about $32 each,this was in the late 1980's!!! Not cheap. I had a 302 Z/28 motor that had some in it with less than 5,000 miles on them. I sent them off to a service that would re-radiuus the lifters...Guy said I might be better off going with a 100inch radius rather than the 120inch that was OEM specs....I called Bullet Cams and asked them....Yes! They said that would be better, so today after 20,000 miles, the 70 LT-1 just ran 12.98@109MPH through the mufflers and on street tires....TKO600 5 speed with steep 1st gear helps get the job done. Not bad for an old "dinosaur" without EFI or computers....Does have a factory breakerless ignition, and ported "186" heads, factory intake and 0.030 overbore....better rods and 10.5:1 lower compression.
Very interesting. I saw a video tour of a small cam regrinder in Tacoma a few years ago. They said they not only regrind stock cams, but reface stock lifters as well! They said factory lifters, reground, are much more reliable than the offshore crap sold nowdays! I'd never heard of reground LIFTERS before then, or since...until now.
Uncle Tony: “heavy duty gear head nerd stuff”
Me: leans in closer and turns up the volume
Absolutely brilliant video Tony!!
This is why I love you and your content so much dude, you don't just talk about things, you KNOW about things. The taper being a part of harmonising the cam shaft when off throttle... Genius! Its stuff like this that I just love. Superb stuff, thank you very much for all your work dude!
My uncle's engine of choice in his race boat was Australian Chrysler hemi 6, but he kept breaking oil pump drives due to non retained cam in early version. Fortunately he worked in the local Chrysler factory, so his boat became a R & D rig.
Hit the nail on the head again Tony! Love how you break down these tiny details and make the knowledge accessible. Entertaining and informative. Thank you!
47 years old and have always been an old car/pickup guy. I’ve always been intimidated by this stuff. You make it easy and enjoyable to learn.
Hey Tony,
Tim here, altho i know about the wear patterns, and lifter spinning, i LOVE gearhead nerd stuff!!!!!...i am a gearhead nerd!!!!!...ur vid was spot on, concise, and usefull for all them youngbloods......enjoyed it......u can make a gearhead nerd vid EVERYDAY as far as i'm concerned...hahaha.....good stuff...PEACE to you sir!!
I love this nerdy stuff! I also love learning the little intricate stuff like the taper is actually ground on opposite sides of the lobes to help with cam endplay! That's awesome! They really thought of everything when building these engines back in the day.
All I got out of this video is confirmation that Uncle Tony is a sorcerer dealing with black magic of the highest order.
Im 75 and just learned something from this vid. Im peggys hubby, and build hot rod engines, and have learned so much from you , andy, and david vizard ! Keep doing these vids. !
Very informative video. A video like this showing how to read crank & rod bearings would be great too, if you ever get a chance.
I love this stuff. Uncle Tony, if you'd do an automatic transmission disassembly while naming each parts function I would be tickled. Then reassemble part by part. If that's too much to ask, then how about doing a shift kit install whilst explaining how it improves shift performance and why. There's plenty of videos on that subject but I retain the info better when I hear it from you... Thanks, Little Mike
I recently pulled the cam out of a AMC 360 after a 25 MINUTE CAM BREAK IN . 15 nos flat tappet lifters and 1 China lifter . The China lifter did not servive. I spent a bit of time looking at the cam ware patterns and could definitely see all of the wear patterns that you talked about on this type of cam style. Your vids are in sink with my build progress. New cam and lifters on the way. Johnson hylift lifters, made in michigan coming with the new cam . I'm that nerd
I looked at the website, and it seems they only make roller lifters. I wonder why people can't make solid lifters anymore. It seems it would be simple to take a bar of the right material, machine it to size and machine (or grind?) a taper on the face.
Every gear head should know and understand this great video!
Thanks Tony for the super informative cam tutorial, I learned a tremendous amount. Pictures with words is golden! Well you are at 100F, we've got 50F in NE PA, I'd take my temps any day! Have a good one Tony!
This is about the best video on how to be a ninja I’ve ever seen no one has covered the topic of lectures wear patterns. In 16 minutes one can teach shop class professionally outstanding work Tony
There's so many details that seem trivial but are really foundational to understanding what we're trying to do with our cars. You keep teaching me stuff I didn't know I needed to know
Ohhh Tony! You came sooooo close to having the world's first Stunt Cam!
I learned my lesson. I grew up in the 70s in Detroit. I grew up seeing all of the best muscle cars. Fast forward 40+ years. I bought a 1978 Trans Am. I didn't do my research. I was just a kid in the 70s. I used oil without zinc. I blazed through my Cam within two summers of driving. I had my engine rebuilt completely and went back with a somewhat radical Cam and headers. I now run the correct oil w/zinc and I am heading into my 3rd year since rebuilding the engine. And.....I continue to watch UTG to learn more and more.
I love this kind of detail. Enhancing the understanding of how things work and why some work well while others do not. Great insight, Tony. I have shared this and the Hemi camshaft issue video, as well as saving them to my archives. Keep them coming...us gearheads love, want, and need them. Thank you for doing what you do
Agreed 👍
Have you noticed other channels, how they seem to be showing off their knowledge more than they're trying to help the viewers understand? They may not be deliberately doing that but it seems that way to me.
These videos do help demystify the issues with camshafts that I keep reading and hearing about. I think they went back to non-tapered camshafts for some newer USA overhead cam engines. I have a 2007 2.0L Ford Focus duratec, and it has flat tappets. I am pretty sure I read that they are offset to keep them rotating, but do not recall 100%. By the way, as far as modern USA engines go, I think that the 3.0l Ford duratec (like in the 1996 Taurus) and the 2.0L Ford Duratec (Like in the USA Focus) are pretty good. I have about 295 thousand miles on my 2007 Focus with manual transmission. Though I did remove the intake tumble flaps.
This is absoposolutely the best instructional video! thank you Uncle Tony!
Good info. I always enjoy your tech vids, because of how you explain stuff. I have such a hard time explaining these to "normal" people, and end up way over their head lol
More nerd stuff! Thank you sir! This is exactly what ppl like i need. Some tuner guy told me my cam was shot but could not explain me why he came to that. I now know he just wanted to sell me a new one.
In 15 minutes I learned more about the cam and lifter interactions than watching all other videos including tv videos. 👍🏼👍🏼👍🏼
That was cool! Most tech talk bores me to no end but this one kept me locked in until the end.
Personally, this is the type of stuff I watch your channel for. I like the tech videos best.
The part about the Helical gear leading/lagging & pushing/pulling was an "Ah-Hah!" moment - Thanks Uncle Tony!
Zinc very important. But the oil manufacturers took it out a few decades ago. That's why I always add about 3oz of Lucas assembly lube when I do an oil change. I have a dodge ram with the 5.7 Hemi which are supposed to eat lifters. I have over 160K miles with no issue's. I credit that to the zinc. Also have a 98 Nissan frontier with 300+K miles and it runs like a top.
I started running royal purple HPS in all my older cars,even the diesels.
Hemi engines did have lifter issues on some but it wasn’t a ZDDP related problem. All your SP engine oils have approximately 700-800ppm of ZDDP which is more than sufficient for any stock roller cam engine. It is woefully lacking for old school flat tappet cams whether stock or not.
Gotta luv the gearhead monk....luv the topic I always learn something new with UT....never a dull video or topic with this guy. The cams survived the video...lol.
I learned something new! Makes me really lean toward roller next engine I put together. I loved the little truth bomb about the zinc pennies as many people still think they are a copper alloy as they were before 1982. Great video again!
One additional source of lube is the rod side clearance .Always check this when building your engine and err on the larger size . I"ve run up to .030 side clearance on a mostly street build with less than 450 hp. I also use a lifter galley shield that has 3 functions . 1- keeps hot oil off the bottom of the intake, 2- helps keep oil around the lifters and 3- helps retain the lifter incase of a push rod failure. Also ,when building the engine always check the lifter bore with a new lifter before you have any machine work done . Make sure it spins freely ! this way you can tell your machine shop weather to hone the lifter bores or not { or just give them the lifters }. One last thing , before assembly , slide the new cam in and make sure it goes all the way in ! Sometimes blocks have a core shift from the factory .I found this out on a 1968 440 block. I took it to a shop and they confirmed it and used a cam bearing cutter to take a couple of thousandths off. Hope this helps a few people.
I’m currently installing a CompCams “Thumper cam” in my Chevy 350, a little nervous about break in but really excited to see the results!
I got 6qts of CompCams break in oil and then for the oil to run after that I got Lucas “hot rod” oil that has the added zinc for old school engines
Use the silver never sieze on cam and lifters for break in do not get any on the sides of your lifters they need to rotate 15 min 3000 rpm change oil.
Don't be timid on the startup.
Once it fires up and you don't see gushing fluids in 10 seconds ,bring the revs up to 2000-2500 to get those lifters spinning and proceed.
I love failure analysis, that's the best stuff ever.
Just love this kind of information! Thanks Tony! Reminds me of your air scoop video. Fantastically interesting to me and others , I’m sure!
Good stuff 👍 something on oil control inside the engine, pros & cons windage trays etc would be good !
I got my license in 1987. I had lots of camshaft problems. Lost a lobe on my 20r Toyota, the 302 in my 79 ltd,a1973,340,a 318 I used while the 340 was out, too many 350 Chevies to remember. One finally got a blue racer cam that was advertised as having more slope to help the lifters spin. Also a 345 international ate a lobe.
Factory cams for thrust plate engines used to be configured so that one lifter would usually be forward, the next in the valve opening sequence, intake or exhaust, would be the opposite, back, then front, back etc.
Thanks. Tony again for sharing your wealth of knowledge. Regards from Australia 🇦🇺
That was a very cool video, Uncle Tony.
Correct on the lobe taper and lofter crown. But every flat tappet 6cyl and 8cyl USA and Aussie based engine I have built uses some lobe to lifter centerline offset. On inspection during build mock up if there is insufficient offset thus gets corrected in one of many mannors depending on how many need attention. Sometimes playing with thrust plate and shimming it as well as machining the timing set or cam to move the entire cam back or forth or narrowing a lobe(requires re heat treating) or lifter bore machine an resleeve to get offset.
Roller cams do show a wear pattern and can give clues as to condition because the roller wheel face on the lifter is not flat, it has a slight crown just like a flat tappet but in the case of a roller this is to stop the sides of the roller wheel from ripping into the lobe due to the lifter having some rotational movement either side of its capture by dogbone, link bar, key way, tray etc and to allow for lifter bores that are not quite perfectly in line with the lobe.
Thanks Tony, that was very helpful. The other topic was valve guide seal. Teflon its what my brother used back in 82' on 77' 351mod. 400 heads. Economy performance cam. holly 650 dbl pumper. I saw your vid where you covered it. A company makes them now. It prevent the morning puff of smoke from the drain down on an older motor.
Might be motorhead nerd stuff, but it's very important motorhead nerd stuff. Thank you for another very informative video UT.
Thanks for the informative lesson! Please consider doing more on cams, like lift and duration and what that boils down to in practice, with different rocker ratios. 👍👍👍
Thanks Tony....that was very interesting, I love all the nerdy stuff I never learned.
Thank's Tony, answered questions I didn't know to ask...
UTG, I never stop learning things from you. Great channel!
This example is a big one that my daily driver, a 1977 Buick Regal with a 350-H with over 310k miles on it this is how I drive it and I’ve converted the RGS-2 carburetor to manual choke and I’ve installed remote oil cooler and engine oil filter assembly with a lot of oil lines for the installation. In the morning cold start I watch the oil pressure closely and bring the rpm up gradually to 1,500rpm this procedure happens in probably less then 60 sec. Then I hold the engine at 1,500 rpm for 1 to 2 minutes then backdown to maybe 1,209 for a minute or so. A lot of this depends on the time of year. Now I’ll talk about curb idle settings. Factory is 750 in gear 850 out of gear; to me that’s to slow and also effects engine oiling. About 99% of my driving is in-city. With long wait times at traffic lights ; some as much as 2 minutes. So I’ve set my curb idle out of gear to 950 rpm which has a positive effect on oil pressure. Every stoplight I’m at I will shift the transmission into neutral as I’m waiting for the light to change, then slam it into drive when the light turns green. Sometimes I will raise the idle at a stoplight to 1,100 rpm if I feel need be. All this happens real fast and I’ve been doing it for years. It’s become automatically for me. One thing if your wondering about my transmission????. The car from the factory and I’ve had rebuilt is a TH400, with a transco level 2 shift kit and a high stall converter. So it goes into gear real fast. All this is about maintaining better oil splash lubrication at low engine rpm.Also I use valvoline VR-1 racing oil faithfully. My engine is one happy smooth running motor on valvoline oil. It doesn’t matter what it is my engines run smoother on valvoline motor oils and I’ve used them for decades.
Well done uncle Tony loved it! Tell uncle Kathy and the guys at the shop I said hi:) have a good day man:)
if you're going to do this then you may as well do rear end ring gear wear patterns! anybody who's built a rear-end knows that they show you 50 different wear patterns when you apply that yellow paint some that are acceptable some that aren't but I'd like to get your input on this and take a look at a ring gear that has a hundred plus thousand miles on it!
Wow! I'm only 3:00 into the video and have already learned some great and interesting info! Very good content thank you so much
Excellent video Tony. This is stuff I never even thought about. You are brilliant and you know so much. Please, keep sharing, I love it.
Thank you for all the fantastic info I'm fixing to pull out three or four old cams and check them out that wiped a few lobes back in the late '90s when Mobil 1 oil was all the rage and it had no zinc in it even the Chevrolet instruction manual that came with the camshafts said do not use anything besides natural crude based oil and specifically warned against using synthetic motor oil with their camshafts they were ground by crane this is for big block Chevy (l88 cam in 454 , 781 heads, 11:1 etc) once again thanks for the great info!
Interesting. I knew about the taper on the cam and of course why it's there but never really paid attention to the difference between how it's done on different blocks or manufactures.
Interesting - thanks. CHEERS from AUSTRALIA.
ANOTHER GREAT VIDEO TONY. THUMBS 👍! I Learned something new. Thanks for sharing .👍
I love this content. I could listen to these bits of knowledge for hours.
HOWdy U-T-G,
Thanks for the INFORMATION
COOP
...
This is a _great_ video. Makes me want to go out and collect all the engine tools I've sold throught the years, sneak an engine stand up into my second-floor apartment along with torque wrenches, a degree wheel, a flow bench and an engine dyno. Start tomorrow.
UT, another excellent educational video.
😎👍
LOVE the nerd stuff Tony! Keep ‘em coming!
Than you Tony, just the sort of content I love from you. Now I’m going to obsess about the engineering choices of the manufacturers, thrust plate or not…
Great content! Would you please explain the relationship between decelaration of the engine and cam pushed at front? Thanks!
Very educational, thank you for explaining it so well
The thrust plate is to stop the cam rolling off the bench. Great Vid'.
I learned quite a bit. Thanks U. Tony
Nice video UTG! Great information! 🤩🤩🤩🤩
Informative topic.....I'm fairly certain the distributor gear's Location generates the Majority of the camshaft's Linear thrust Direction so the Rear located distributor engines require a Front located camshaft thrust plate....The Front distributor engines use the camshaft sprocket to function for the thrust plate so no Separate plate is needed.....
Great video, you have a knack, thanks for making it.
This information is quite impressive, definitely something I didn't know, excellent video, thanks, all the best to you and your loved ones
Thanks so much Tony! I never knew all that..
I almost passed on this video!
It was awesome. I remember first learning about a thrust plate when I BROKE mine on my 318.
It was the 80s and had a heck of a time finding a new one.
Now I know what it does.
I learned something tonight, thank you.
I asked and you provided. Thanks UTG
Most people don't relize that this info applies to modern engines including that OHC/DOHC I took my 95 Saturn Twin Cam apart with 90,xxx to modify. Note I ran oil without zinc. Upon inspection, the cams had bad wear. No tapper wear look to the cam. It uses a flat style tappet, (called a bucket) that sits between the cam and valve tip. The crown was now a concave. It will get a zinc rich oil or additive.
That was awesome! I learned so much. This is why this channel is the power house that it is. And will always be. And I still say that brakes are for quitters!
You might have a post on the lifters. There is a lot to know about them too. Seen 'em flat, mushroomed, burnt, many internally stuck, etc..
I learned something new! Thanks Tony. I always wondered what made the lifters spin.
Call me a nerd, but this stuff is so educational. Thanks Uncle T. Auto mechanics class in High School was never like this. (1960's)
Another great classic engine educational video about camshafts and flat tappet lifters. Again, you really need to investigate teaching auto shop at your local community college. 👍
A very nice explanation of the wear pattern, thanks. Now here's where you need some help. ZDDP is NOT the be-all to end-all, and I've also seen a past video (think it was on Vizards channel) where you said you are using Rotella.
Rotella "gas" formula is better than the diesel for wear protection, but even the best Rotella, does not compare in film strength to the better synthetics. As a matter of fact Rotellla gas truck motor oil has about 37% less wear protection than the best synthetic on the market.
Zinc/ZDDP additives may or may not work. Film/sheer strength is what you want. A fllm /sheer strength of 120,000 psi is desirable for flat tapped OHV engines. Rotella is about 96,000 psi. vs something like a 10W40 Quaker State All Mileage (conventional oil), which is rated at 126,000 PSI. If you added ZDDP to Rotella, I highly doubt you would get the same protection as the Quaker State. And how much do you add? Unless you know what the Film strength is, you're pissing in the wind.
Want to know where to obtain this info? Respond, or you may know it already. So for anyone interested, reply and I will divulge where to find what every motorhead needs to know. I'm sure there are others reading this , who know what I'm talking about.
This was good. Did you know that Ford 460 engines have a thrust plate yet all the lobes are ground high to the rear of the engine. Why? Who knows.
I just reground a circle track camshaft that had about 10,000 laps of running using the same profile and it is very interesting to see what the wear pattern looks like as the lobe cleans up. In this case it took about .004 and the place with the most wear was not over the nose but on the flank just before the nose. Sort of a little football shaped patch that took a couple of thousandths of grinding to clean up good as new.
Would you do a carb video on tuning the spring on vacuum secondary carb, and choosing the correct metering plate for it?!
Who still remembers in the 80's when GM had soft camshafts .
Got into wrenching towards the end of that.
Diagnosed one once ,and not seeing some valves open as much as others, called the boss over to ask wtf and he chuckled.
Easy diagnosis. If you revved one and it backfired on decel it was camshaft time.
I was asking for this very thing, thanks Tony!
He knows his stuff,
I gained some knowledge
More great information thanks Tony
I've seen one engine with a camshaft that was lubricated quite differently; a 2.3 liter (140 cubic inch) Pinto engine. I turned it over with the valve cover off and observed pressurized oil spurting from holes on the lobe wear surfaces. As an aside, it had crud in these holes, apparently from lack of oil changes.
Looks like all generalities have exceptions. 🧐😎
That's hardly an exception. The pinto engine is over head cam so the crank and rods can't splash oil on it. Tony is describing how the cam and lifters are lubricated on a classic v8 engine. I get to see the oil tube in my brothers pinto whenever I have to remove the valve cover.
Excelant video U.T.....your presentation was excelant....!..."motor head nerd stuff"..lol...love it...another U.T. clasic...!...thank u...
Uncle Tony I'm glad you made this video because I do use cams in my engines you know that's why I take a micrometer with me to check my lobes to see if and and check and make sure that this camera is still functioning and can this can be repaired or not thank you and keep up the good work holla if you hear me
Whats going on with the cam on your left at 6:18 / 6:22 give or take a bit, it seems to want to go to a heavy side down. Try to get your work bench as level as possible and roll the cam, it will want to stop with the same place down every time, a balance issue! Even better drill on center and tap the ends of the cam and mount it with some easy spin bearings and see even at slow rpms it will want to get away from your grip. I learned from this that some lobes are ground so the cam wants to self center front to rear using the lobe taper and gear for the oil pump and distributor drive. I once worked on a motor where the cam gear managed to move on the camshaft making for quite a bit of end play, talk about a weird running motor as the timing was all over the place both valve and ignition, it was a gear drive sit up with helical cut gears on both the cam drive and the distributor drive. Some times it would idle fine the next time like a race cam and every thing in between!!
Great video and love your catlike reflexes @ 6:16
no this wasn’t too much info. thanks for this! 👍🇨🇦
25 years ago, I had a cylinder head remanufactured for a Ford Escort. 3000 miles later, loud lifter clacking and loss of oil pressure. Turns out, they resurfaced the lifters when they rebuilt the head. The lifter foot ground all the way through to the inner bore. All that metal went through my engine. I was a pissed off fellow. Resurfaced lifters are a thing especially with large engine remanufacturers. Powell machine has a great video on this problem.