BBC solid roller lifter failures - a root cause analysis
09-30-2008, 02:42 PM
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BBC solid roller lifter failures - a root cause analysis
Like everyone else who is interested in BBC solid roller lifter failures, I wondered just what is really causing all these failures. Everyone talks about the problem, and some have ideas how we can make them live as long as possible. But at the end of the day, most all of them are going to fail, no matter what you do to try to help them, at a time/mileage that most of us consider premature. Yes, there are some reports of long lives, but that is mostly luck of the draw and not something that you can count on with any regularity.
As far as I know, no one has ever done an actual root cause failure analysis on these lifters to see what is really going on. So, in an effort to preserve my own nearly finished 540, I decided that if I wanted that info, I'd have to do it myself. So, I thought I'd post my findings for others who might be interested as well. I managed to get my hands on failed std diameter .842 solid roller lifters from 3 different BBC's. I would have liked a wider sampling, but these 3 motors spanned the spectrum from relatively mild to relatively wild. The specs are:
1. 408ci BBC, 243*/249* at .050, .663"/.655" lift, .018/.020 lash, 210/567 lbs spring pressure, Chevron Delo 15W40, Isky Redzone lifters failed at 3,000 nearly all street miles.
2. 540ci BBC, 266*/272* at .050, .678"/.688" lift, .016 lash, 260/650 lbs spring pressure, Redline 20W50, Crower HIPPO's failed at 5,000 nearly all street miles.
3. 632ci BBC, 277*/292* at .050, .848"/.824" lift, .026/.028 lash, 325/875 lbs spring pressure, Mobil 1, Redline, and Royal Purple Racing 20W50, Crower HIPPO's failed after 1 1/2 years. Mileage and driving style not documented.
So, I took them apart one at a time for careful analysis. I figured to get to the bottom of it all, if needed, I'd also Rockwell test the parts and send them to a metallurgy lab for detailed analysis. As it turns out, no matter what the cam, lash, springs, or oil used, they all suffered from the exact same mode of failure, in the form of extensive surface pitting on the axles and needles, which is also called spalling (no indication of an oiling problem such as galling was found at all). The axles were the worst in all cases, which make sense, since they are softer, which allows for the swaging at their ends which holds them in place. All this pitting is caused by metal surface fatigue failure. And this is brought on by the part being overloaded for its size, which sends the stresses of the metal so high, that its fatigue life is lowered to an unacceptable level. Since this failure was totally obvious, much like a bullet wound through the head, the cost and hassle of further analysis was not necessary. That being the case, there is essentially no defense against this fatigue failure with .842 lifters. They are just too small for the job we ask of them. If they are made bigger, and of course some are available a bit bigger (though they may not really be big enough for acceptable fatigue life), then the stresses can be lowered, thus increasing fatigue life. Using .842 lifters is just convenient for use in existing lifter bores, but this size is not what engineers would design from a clean sheet of paper, or a blank computer screen, for an application such as this. All most can do is closely monitor things to see when they start to go. And hope you can replace them before they take the engine with them. The other thing that was very bothersome about all 3 sets of failed lifters, is the fact that the roller OD's all showed the same fatigue failure pitting. Some had totally failed, and some were just beginning to fail. And with all different oils, cams and spring pressures being used, showing the same problem, there is really no defense against fatigue failure here either. This failure is actually worse than a needle/axle failure, because with close monitoring, you can usually catch the needle/axle failure before it takes anything else out. But with a roller OD failure, by the time you see it show up in terms of extra lash, it is almost guaranteed to have already taken the cam lobe with it, and perhaps even more. Not a very comforting thought.
Since I now see that the needle-type solid roller lifters for BBC's are basically hopeless, I pulled the new Crower HIPPO's out of my as yet un-fired brand new 540, and replaced them with newer Isky EZX bushing-type roller lifters, since they are more or less the only game in town for that type design. By all accounts that I've come across, these EZX's are much more durable than the needle-types, with respect to the needle/axle problem. So I'll give them a try, even though I really don't like some of their other design aspects. I suppose overall, they can't be any worse than the needle-types, and will hopefully be much better. But, unless those EZX's have better material being used for the rollers, than the basic Redzones, then they also can only last as long as the roller OD's, no matter how well the bushing/axles hold up.
For those who might be interested, here are some things I came across when installing those Isky EZX's in my Dart Big M block with its Comp Cams billet custom solid roller cam:
1. The diameter was larger than Isky told me they would be, thus reducing the lifter to bore clearance to less than I'd really like, but the motor was built already at this point, so honing the bores was not an option. It should be OK, but it is at the minimum, so it does concern me a bit.
2. The pushrod seats were about .040 higher than were the seats in my previous Crower HIPPO's, so I had to get another set of shorter pushrods to maintain the rocker geometry that I had ever so carefully setup with my AFR 335cc CNC heads. So, that cost me even more money, even though Isky told me there would be no change in that regard.
3. Isky's so-called high pressure bushing oiling holes are horizontal holes just above the axle, in the front to back direction, and do not get oil through a passage from the pressurized oil band up above like the Crowers and other lifters do. These Isky bushing/axle oiling holes hang below my lifter bores when on the base circle, where they get no oil at all half the time. Those oil holes will see some oil when they are up in the lifter bores, where there is some oil pressure, though restricted by the amount of lifter to bore clearance available. And they will also see a shot of actual pressurized oil during the relatively brief time (maybe 90* camshaft, give or take), when the holes reach the block's lifter oil galley at max lift. But the way the bushing/axle gets most of its oil, most of the time, is because there are oil holes above the roller, shooting oil onto the OD of the roller. The spinning rollers will throw the oil off and outward just like water off a spinning tire in the rain, but it hits the underside of the lifter body, and then comes back down the sides of the rollers onto the axle, where it can sort of work its way into the actual bushing/axle interface. Overall, I don't like this poor oiling design. Though it does apparently work well enough to get by. But, having the bushing/axle area get consistent fulltime oil directly from the oil band like other lifters do, would be far superior.
4. The lower thrust surface below the large oil band, is really way too short. It doesn't wrap somewhat around the roller like the Crower HIPPO's do, which is a much better design altogether. Some of the Isky's I took apart, showed excessive wear on that shorter thrust surface below that oil band. This is also an inferior design aspect that I don't like.
5. The precision outer diameter surfaces of the lifters were not machined high enough, which I didn't expect to have to look for originally, and so I had 3 lifters stick in their bores. All they had to do was machine about another .100 higher, and it would be no issue. My original Crowers were machined correctly, but the Isky's were not.
6. The one good thing I found with the EZX's is that the large pressurized oil band is lower than they were on my previous Crower HIPPO's, so they don't try to restrict oil flowing through the lifter oil galley like the Crowers would at max lift.
All in all, I was not very happy with my $1,000.00 Isky purchase. But considering the solid roller lifters available, they apparently are the lesser of evils. So, I'm crossing my fingers and hoping that they will hold up better than the rest. I guess guys like us who insist on running solid rollers on the street are a bit crazy………..
As far as I know, no one has ever done an actual root cause failure analysis on these lifters to see what is really going on. So, in an effort to preserve my own nearly finished 540, I decided that if I wanted that info, I'd have to do it myself. So, I thought I'd post my findings for others who might be interested as well. I managed to get my hands on failed std diameter .842 solid roller lifters from 3 different BBC's. I would have liked a wider sampling, but these 3 motors spanned the spectrum from relatively mild to relatively wild. The specs are:
1. 408ci BBC, 243*/249* at .050, .663"/.655" lift, .018/.020 lash, 210/567 lbs spring pressure, Chevron Delo 15W40, Isky Redzone lifters failed at 3,000 nearly all street miles.
2. 540ci BBC, 266*/272* at .050, .678"/.688" lift, .016 lash, 260/650 lbs spring pressure, Redline 20W50, Crower HIPPO's failed at 5,000 nearly all street miles.
3. 632ci BBC, 277*/292* at .050, .848"/.824" lift, .026/.028 lash, 325/875 lbs spring pressure, Mobil 1, Redline, and Royal Purple Racing 20W50, Crower HIPPO's failed after 1 1/2 years. Mileage and driving style not documented.
So, I took them apart one at a time for careful analysis. I figured to get to the bottom of it all, if needed, I'd also Rockwell test the parts and send them to a metallurgy lab for detailed analysis. As it turns out, no matter what the cam, lash, springs, or oil used, they all suffered from the exact same mode of failure, in the form of extensive surface pitting on the axles and needles, which is also called spalling (no indication of an oiling problem such as galling was found at all). The axles were the worst in all cases, which make sense, since they are softer, which allows for the swaging at their ends which holds them in place. All this pitting is caused by metal surface fatigue failure. And this is brought on by the part being overloaded for its size, which sends the stresses of the metal so high, that its fatigue life is lowered to an unacceptable level. Since this failure was totally obvious, much like a bullet wound through the head, the cost and hassle of further analysis was not necessary. That being the case, there is essentially no defense against this fatigue failure with .842 lifters. They are just too small for the job we ask of them. If they are made bigger, and of course some are available a bit bigger (though they may not really be big enough for acceptable fatigue life), then the stresses can be lowered, thus increasing fatigue life. Using .842 lifters is just convenient for use in existing lifter bores, but this size is not what engineers would design from a clean sheet of paper, or a blank computer screen, for an application such as this. All most can do is closely monitor things to see when they start to go. And hope you can replace them before they take the engine with them. The other thing that was very bothersome about all 3 sets of failed lifters, is the fact that the roller OD's all showed the same fatigue failure pitting. Some had totally failed, and some were just beginning to fail. And with all different oils, cams and spring pressures being used, showing the same problem, there is really no defense against fatigue failure here either. This failure is actually worse than a needle/axle failure, because with close monitoring, you can usually catch the needle/axle failure before it takes anything else out. But with a roller OD failure, by the time you see it show up in terms of extra lash, it is almost guaranteed to have already taken the cam lobe with it, and perhaps even more. Not a very comforting thought.
Since I now see that the needle-type solid roller lifters for BBC's are basically hopeless, I pulled the new Crower HIPPO's out of my as yet un-fired brand new 540, and replaced them with newer Isky EZX bushing-type roller lifters, since they are more or less the only game in town for that type design. By all accounts that I've come across, these EZX's are much more durable than the needle-types, with respect to the needle/axle problem. So I'll give them a try, even though I really don't like some of their other design aspects. I suppose overall, they can't be any worse than the needle-types, and will hopefully be much better. But, unless those EZX's have better material being used for the rollers, than the basic Redzones, then they also can only last as long as the roller OD's, no matter how well the bushing/axles hold up.
For those who might be interested, here are some things I came across when installing those Isky EZX's in my Dart Big M block with its Comp Cams billet custom solid roller cam:
1. The diameter was larger than Isky told me they would be, thus reducing the lifter to bore clearance to less than I'd really like, but the motor was built already at this point, so honing the bores was not an option. It should be OK, but it is at the minimum, so it does concern me a bit.
2. The pushrod seats were about .040 higher than were the seats in my previous Crower HIPPO's, so I had to get another set of shorter pushrods to maintain the rocker geometry that I had ever so carefully setup with my AFR 335cc CNC heads. So, that cost me even more money, even though Isky told me there would be no change in that regard.
3. Isky's so-called high pressure bushing oiling holes are horizontal holes just above the axle, in the front to back direction, and do not get oil through a passage from the pressurized oil band up above like the Crowers and other lifters do. These Isky bushing/axle oiling holes hang below my lifter bores when on the base circle, where they get no oil at all half the time. Those oil holes will see some oil when they are up in the lifter bores, where there is some oil pressure, though restricted by the amount of lifter to bore clearance available. And they will also see a shot of actual pressurized oil during the relatively brief time (maybe 90* camshaft, give or take), when the holes reach the block's lifter oil galley at max lift. But the way the bushing/axle gets most of its oil, most of the time, is because there are oil holes above the roller, shooting oil onto the OD of the roller. The spinning rollers will throw the oil off and outward just like water off a spinning tire in the rain, but it hits the underside of the lifter body, and then comes back down the sides of the rollers onto the axle, where it can sort of work its way into the actual bushing/axle interface. Overall, I don't like this poor oiling design. Though it does apparently work well enough to get by. But, having the bushing/axle area get consistent fulltime oil directly from the oil band like other lifters do, would be far superior.
4. The lower thrust surface below the large oil band, is really way too short. It doesn't wrap somewhat around the roller like the Crower HIPPO's do, which is a much better design altogether. Some of the Isky's I took apart, showed excessive wear on that shorter thrust surface below that oil band. This is also an inferior design aspect that I don't like.
5. The precision outer diameter surfaces of the lifters were not machined high enough, which I didn't expect to have to look for originally, and so I had 3 lifters stick in their bores. All they had to do was machine about another .100 higher, and it would be no issue. My original Crowers were machined correctly, but the Isky's were not.
6. The one good thing I found with the EZX's is that the large pressurized oil band is lower than they were on my previous Crower HIPPO's, so they don't try to restrict oil flowing through the lifter oil galley like the Crowers would at max lift.
All in all, I was not very happy with my $1,000.00 Isky purchase. But considering the solid roller lifters available, they apparently are the lesser of evils. So, I'm crossing my fingers and hoping that they will hold up better than the rest. I guess guys like us who insist on running solid rollers on the street are a bit crazy………..
09-30-2008, 03:22 PM
#2
Team Owner
My solid lift roller failure with the cheaper Crowers was just like you said.
they all suffered from the exact same mode of failure, in the form of extensive surface pitting on the axles and needles, which is also called spalling
the pitted wheel also pitted the billet cam lobe. I bought what I thought was the lightest and best so it would not happen again. Both of my solid roller motors use the Crane Cams Ultra Pro's
On set has been in my 7500 rpm 383 for about 4 years and a rebuild. I just had the heads off and inspected my 434 equiped with Crane Ultra Pro's and they were fine. They have been through a broken crank shaft and lots of metal in the oil and now racing this whole year with .685/,714 lift.
I've recommended the Cranes to all my friends.
they all suffered from the exact same mode of failure, in the form of extensive surface pitting on the axles and needles, which is also called spalling
the pitted wheel also pitted the billet cam lobe. I bought what I thought was the lightest and best so it would not happen again. Both of my solid roller motors use the Crane Cams Ultra Pro's
On set has been in my 7500 rpm 383 for about 4 years and a rebuild. I just had the heads off and inspected my 434 equiped with Crane Ultra Pro's and they were fine. They have been through a broken crank shaft and lots of metal in the oil and now racing this whole year with .685/,714 lift.
I've recommended the Cranes to all my friends.
09-30-2008, 04:58 PM
#3
Race Director
Interesting read, seems they can't handle the spring pressure. They were designed in the first place for all out racing applications and then the street rodder wanted them.
Speaking from my experience with a small block, there are cams out there designed for street use. They typically have less than 200lbs seat pressure on the seat.
I still got 550HP from a 406ci with one so they are still pretty potent cams. I ran the old Comp Cams 818's which don't have any oiling holes at all and rely on splash from windage etc.
I put over 20,000 street miles on them and at this point some where beginning to go so I replaced them all. The motor was never raced or held at high RPM's for long so it basically had a easy life
One thing for sure you have to keep an eye on them and I take the intake manifold off and inspect them visually once a year
Speaking from my experience with a small block, there are cams out there designed for street use. They typically have less than 200lbs seat pressure on the seat.
I still got 550HP from a 406ci with one so they are still pretty potent cams. I ran the old Comp Cams 818's which don't have any oiling holes at all and rely on splash from windage etc.
I put over 20,000 street miles on them and at this point some where beginning to go so I replaced them all. The motor was never raced or held at high RPM's for long so it basically had a easy life
One thing for sure you have to keep an eye on them and I take the intake manifold off and inspect them visually once a year
Last edited by MotorHead; 09-30-2008 at 05:22 PM.
09-30-2008, 05:07 PM
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Sounds like from what I can tell there might be some truth to the propoganda crane cams puts out about their "street roller" series solid roller cams.
09-30-2008, 05:39 PM
#5
Is it that Crane is better or is it that gkull talked about was small block? Is there a difference between BB and SB rollers? If not then the Crane comment above may be something to consider. I am considering building a SB 409 or 383 with roller lifter and rockers. Really don't want to waste my money if they aer doomed to fail.
09-30-2008, 05:41 PM
#6
Race Director
They were developed for racing. And there they have a chance to work as the engines are torn down nearly every pass. Spring pressure and rev kits which are necessary were just too much junk to put up with for my Chryslers and the Donovan. My flat tappet never failed me like a few rollers did and I honestly never produced better times with them. The problem is not just the rollers, its the other parts that get damaged in the course of the failure. Knowing this, its the reason my street engines are all flat tappet. I wont even use the rocker arms on the street. Racing, its a different territory. But I won with the flat cams the camshaft companies supplied me, not the rollers.
Plus I hate working on areas of the engine that could cause problems I have already faced running the quarter, especially since I know better. I race to win, not garbage engines.
540`s analysis should be read by more people contemplating a roller cam.
Plus I hate working on areas of the engine that could cause problems I have already faced running the quarter, especially since I know better. I race to win, not garbage engines.
540`s analysis should be read by more people contemplating a roller cam.
09-30-2008, 06:33 PM
#7
Team Owner
Is it that Crane is better or is it that gkull talked about was small block? Is there a difference between BB and SB rollers? If not then the Crane comment above may be something to consider. I am considering building a SB 409 or 383 with roller lifter and rockers. Really don't want to waste my money if they aer doomed to fail.
http://www.cranecams.com/?show=brows...lvl=3&prt=2095
The ultra pros live in the 300+ seat and 800+ open race motors. So things like my wimpy 200# seat and 600# open are nothing.
09-30-2008, 07:59 PM
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Stock blocks BBC and SBC are the smaller .842
http://www.cranecams.com/?show=brows...lvl=3&prt=2095
The ultra pros live in the 300+ seat and 800+ open race motors. So things like my wimpy 200# seat and 600# open are nothing.
http://www.cranecams.com/?show=brows...lvl=3&prt=2095
The ultra pros live in the 300+ seat and 800+ open race motors. So things like my wimpy 200# seat and 600# open are nothing.
09-30-2008, 08:19 PM
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I've pretty much decided to go with hydraulic rollers for my street BB. I'll loose some HP, but the hydraulics are a lot more durable....or so I've been lead to believe.
I notice that the spring pressures on the hydraulic rollers are noticeably less than on the solids. I'd imagine that it's the spring pressures that are really killing the solids.
...Very interesting post.
I notice that the spring pressures on the hydraulic rollers are noticeably less than on the solids. I'd imagine that it's the spring pressures that are really killing the solids.
...Very interesting post.
09-30-2008, 09:39 PM
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Good stuff as usual Rick. Thanks for posting!
You guys would have to know Rick.....he's that guy you've heard about. He can't sleep until he finds the real cause of failure. Doesn't hurt that he does it for a living! He's been at this solid roller thing for a couple of years now and has spent considerable time and $$$ to learn what he has.
Thanks Rick for sharing with us!!
BTW- you're dead on about small blocks. Yes they use same basic lifters with all the same problems,.....BUT....they don't have the big block issues. The pushrods go straight, the valves are lighter etc etc etc. It's a lot easier for them to rev and it doesn't hurt parts as much. It doesn't take as much spring pressure at all.
The HR's are another deal. Basically you have such a mild lobe..and low spring pressures...they can run a long time. A good solid flat tappet can still outrun one down the track or street due to be able to rev a lot higher. People are doing all sorts of things to get them to rev higher....and spring pressures are going up. You'll soon be seeing same issues with them in the serious HR categories.
I have a buddy with an old school Lunati HR in his 502. It runs low 10's in the 1/4 and revs 6700 anytime you want to with 5 year old springs. The trick is it's a relatively *soft* slow moving lobe with a lot of duration. It doesn't have the best street manners...but it does run when you stuff your foot in it!
I'm deep off into a HR BBC project we're building for a buddy. We're utilizing all the smartest folks we can find to get some RPM out of it...we'll see how it goes. Dyno results will be coming!
JIM
You guys would have to know Rick.....he's that guy you've heard about. He can't sleep until he finds the real cause of failure. Doesn't hurt that he does it for a living! He's been at this solid roller thing for a couple of years now and has spent considerable time and $$$ to learn what he has.
Thanks Rick for sharing with us!!
BTW- you're dead on about small blocks. Yes they use same basic lifters with all the same problems,.....BUT....they don't have the big block issues. The pushrods go straight, the valves are lighter etc etc etc. It's a lot easier for them to rev and it doesn't hurt parts as much. It doesn't take as much spring pressure at all.
The HR's are another deal. Basically you have such a mild lobe..and low spring pressures...they can run a long time. A good solid flat tappet can still outrun one down the track or street due to be able to rev a lot higher. People are doing all sorts of things to get them to rev higher....and spring pressures are going up. You'll soon be seeing same issues with them in the serious HR categories.
I have a buddy with an old school Lunati HR in his 502. It runs low 10's in the 1/4 and revs 6700 anytime you want to with 5 year old springs. The trick is it's a relatively *soft* slow moving lobe with a lot of duration. It doesn't have the best street manners...but it does run when you stuff your foot in it!
I'm deep off into a HR BBC project we're building for a buddy. We're utilizing all the smartest folks we can find to get some RPM out of it...we'll see how it goes. Dyno results will be coming!
JIM
09-30-2008, 09:54 PM
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Jim,
Its not a big block but it is a high revving small block.
http://www.camaroz28.com/forums/showthread.php?t=636309
Its not a big block but it is a high revving small block.
http://www.camaroz28.com/forums/showthread.php?t=636309
09-30-2008, 10:09 PM
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I have tried to pull the RPM out of my current motor. Still use the solid roller but longevity may be found staying below 6500 with a solid street roller. I have seen problems with slight float or even detonation that might cause the pitting. It only takes slight preignition to load those needles with incredible pressure.
09-30-2008, 10:39 PM
#14
Team Owner
George, its good to hear that you've done well with your Crane Ultra-Pro's, but they still have needles in them. That being the case, it would seem that you are playing Russian Roulette with your motor. I hope you don't have any issues, but you are braver than I am. I tossed the needle-type lifters (well, tossed out of my 540, but I still have them), and I'd never risk using them again. But then, it is Big Blocks that seem to have all the trouble.
Years ago I used aluminum rockers in a drag race motor with high ,780 lift and the needles would actually dent the inside of the rocker shaft.
Motown blocks have a revised oiling system with a closed cam valley. I had my heads off for a problem a month or so ago.
I had that side vent welded shut and went to a twin breather K&N
Last edited by gkull; 09-30-2008 at 10:42 PM.
09-30-2008, 10:59 PM
#16
Team Owner
I was willing to try anything once. These Horizontal bars were sold by Crane and Crowler. It beat up my cam during a road race weekend at Thunder Hill
09-30-2008, 11:43 PM
#18
Team Owner
It's what 540RAT was talking about. The roller wheel needles fail and the roller wheel starts bouncing on the cam lobe. This was on my 7500 rpm all the time 383. I did some long road trips in the Vette and it might have been in the 15K mile range and a couple of years. The JE pistons with 1/16th inch rings were gone. It was time for a rebuild anyway
10-01-2008, 02:01 AM
#19
Team Owner
It would be very interesting to do a microscopic analysis of some of the less damaged needles/axles/rollers in a set that had experienced a failure. Since the badly damaged parts show pitting/galling on all of the working members, you really can't tell which components started the failure. Once pitting begins...and propagates to the other pieces, the initial cause is masked. If you could find a roller that showed the initial stages of failure, you might find which component showed the first signs of pitting...that would be the "weak link". The other components just suffer secondary damage. High contact loading, poor lubrication, oil film not being able to support the loads experienced--all are contributing to the problem. I would suspect that racing engines have higher capacity oil pumps and run at higher pressures; they also may have methods for assuring oil gets to the 'high load' areas in the engine, which would mitigate this kind of failure.
10-01-2008, 02:32 PM
#20
Burning Brakes
Thoughs are bad for sure, but I think the real quistion is why are they like that. I'm not sure I have heard any real reason here yet. I run these crane Horizontal lifters in my race engine that turns 9600rpm and with 240# on the seat and 700# open with .775 lift and I have used these lifters for well over 375 runs. I also have no oil presure going to these lifters at all. Now this dosn't mean I would never see this problem just means I don't understand what is causeing this problem in these peoples engines. And yes I do hear you guys are trying to drive these on the street also. But you do see that the edges seem to have the most problem in the pictures, meaning what? Too much clearance in the lifter bore, too much camshaft end play, poor lifter bore to lobe alignment? OK so no one asked but I still stuck my .002cents in.