AJay

iTrader: (1)

I have seen a number of posts lately with pictures of heavily spalled Lifter / Cam running surfaces. While most people write this off to a defective cam, I am convinced that after several thousand miles these surfaces run in and effectively form a matched contact surface. Changing to an aftermarket cam without changing lifiters creates a mis-matched running surface and initiates spalling. I note that GM specifies that lifters must be changed when the cam is changed which I expect is for this this reason. I would appreciate the collective thoughts of the "experts" on this forum with regard to this subject.

i.e. Do you agree or disagree that changing a cam without installing new lifters invites (significantly increases the chances for) spalling damage.

Thanks for your input.

hammrman31

i agree.new cam, new lifters.i wouldn't put new lifters on an old cam either.had a bad experince with that.

MrDude_1

iTrader: (4)

GM advises that for flat tappet cams.. everyone pretty much agrees in changing the lifters for flat tappet cams.

but roller cams do not have wear surfaces.. any wear on the hardened wheel or cam is a defect.. this includes the surfaces wearing into each other

AJay

iTrader: (1)

Actually the GM Service Manual for 2001, Volume 2 page 6-383 states "IMPORTANT - If camshaft replacement is required, the valve lifters must also be replaced". This does not surprise me as the roller on the lifter acts exactly like the roller in a conventional roller bearing that would be used in Gas Turbine Engine (my speciality). In my industry (aviation) we would never consider changing a roller bearing and not replacing the outer race as again, the rollers, over time, will wear slightly into the race developing a "matched" running surface.

vettenuts

iTrader: (4)

I have seen this in the manual as well, all I can say is I changed lifters during my recent head change and while the cam wasn't worn, you could definitely see a roller pattern on it. How would this affect life expentancy, not sure. I am also not sure what drives the GM recommendation, it is good insurance from a repair standpoint, a technical reason, or logic that if the cam is worn to require its stock replacement it likely damaged the lifters as well.

Unaffliated Racing

iTrader: (15)

There is a huge difference between the automotive industry and the aviation industry. If an automotive engine fails..the car stops. If an airplane engine fails...that sucker drops out of the sky like a brick and people die. Hence the reason aviation has very strict guidelines. It's not wether or not lifters in an airplane need to be changed as they HAVE to be changed.

AJay

iTrader: (1)

It would be an interesting exercise to check with those who've recently lost lifters / cam due to heavy spalling damage and find out if the lifters were replaced when they changed the cam.

sleepersilverado

iTrader: (1)

got you covered.... when i originaly built my motor i did not replace the lifters BUT it was a crate motor so if it was ran it was at gm and that is it. i tore a new motor down and built it. truck ran great but broke valve springs like crazy.(caused by the head porter setting the springs up out of spec) i put about 20k miles on the motor and then decided to change the cam because of all the trouble. changed the cam and installed the new cam with the same lifters and the expensive a$$ comp double springs. put another 18k on the motor and went south from there. lost oil pressure then changed pump and such. ended up pulling motor then cam. EVERY lobe and roller on the lifters were spalled. some people think i got a bad cam, some think i had too much spring pressure....?... i dont know but this theory is interesting now that i think about it. my thinking is that i ran the motor for 20k miles or a little more and broke valve springs but had no other probs. then went to a smaller lift cam (from .591 to .571) and had probs. i dont see how it can be too much pressure because when the other cam was removed it was in good condition and was even sold. so i dont get it unless the new springs had more pressure although that dont make since because there was less lift. the only other thing is the first cam was billet.

sorry so long

squealingtires

iTrader: (14)

How about a used cam install? Should I get the lobes polished? I will be installing new lifters too? The cam is fairly aggressive 238/240 .60x/.60x The cam has approx. 5k miles on it and the lobes look great but I'm sure there is some wear present

BOWTIE

"IMPORTANT - If camshaft replacement is required, the valve lifters must also be replaced"
If a camshaft replacement is "required" that would imply that it had failed. anytime a roller cam fails, it will also take out the corresponding lifter (or vice versa). Most people on this site are not replacing the cam because it was required, but rather because it was desired... BIG DIFFERENCE.
Also your correlation is rather far fetched, if you are replacing the roller bearings because they are worn out or damaged, yes you would need to replace the race as well, if the lifter is worn it should be replaced as well. When you rebuild a transmission and replace the bearings, do you also replace the input shaft, output shaft, and cluster gear??? Not unless they are damaged. In other words, you do not need to replace roller lifters when the cam is changed unless the lifters are damaged, or could have debris from other engine damage inside them (of course you could take them apart and clean them as well in that case).

white2001s10

iTrader: (4)

I like this thread. It seems that each side is supported to a point by logical reasons. In cases like this I think it's best not to decide the truth based on logic, but on actual test results. It's too bad this is going to be hard to do.

My own impression was that the roller cam and roller lifter mating surfaces weren't really considered a wear-type of contact like flat tappets are. That suggests that wear problems would be caused by defects.

Lafngas

iTrader: (7)

Agreed!!!!!

Cstraub

iTrader: (1)

. . .or lack of lubrication that led to the spauling and is caused by several factors being present to create the situation.

Roller lifters don't have to be changed with every cam change. The lifter needs to be inspected and if suspect to wear then new lifters should be installed.

MrDude_1

iTrader: (4)

you said it before i could.

that manual is assuming you're replacing the cam, due to some kind of damage. not because you're taking apart a perfectly good motor..

sleepersilverado

iTrader: (1)

heck most people dont check the lifter when replacing the cam because they leave the heads on. like said previously this is gonna be hard to prove but the theory sounds fiesable.

AJay

iTrader: (1)

Your point regarding the GM Manual is well taken. Looking at it from your perspective it would make perfect sense to mandate a lifter change if the cam was damaged in some way that would ultimately affect the lifters. And yes, I'm sure the manual was not written around the aftermarket. None-the-less when I see the spalling damage on cams and lifters that some folks have posted recently, I can make direct correlations to the internal damage I see regularly on gear meshing surfaces and bearing surfaces in turbine engines. Some operators will request that damaged roller or ball bearings be replaced with used bearings from different engines. Pratt & Whitney (the manufacturer) will allow this however the bearing must be replaced with the matching races otherwise it will spall out and the next thing we know the engine is making metal. To that end, I see the relationship between a lifter roller and a cam surface exactly as that of a roller bearing and race. To me, the cost of replacing the lifters is good insurance. I would still be keenly interested to know if the guys with the spalled cams replaced their lifters.

2xLS1

iTrader: (25)

If the lobe spauling was caused by running used lifters, wouldn't we be seeing this on just about every brand of cam instead of almost exclusively on only 1 brand of cam and one grind of that brand. They do seem to be replacing them at no cost so that should tell you something.

AJay

iTrader: (1)

One last point to make here is that the GM Manual also states that if Lifters are re-installed, they must be installed in their original locations. If maintaining a matched running surface was not an issue, why would they make that statement?

sleepersilverado

iTrader: (1)

What brand are you refering to? i have not heard but also have not looked

777

iTrader: (21)

Futral and some of comp's (I'm guessing they both get their cores from the same place) This has already been addressed that it was an issue with the core, not the lifters or anything else. I've had 3 different cams. The lifters were 100k miles old and had been used through the stock cam, a 218/220 cam, and a 231/237 cam. Now I put in new lifters just for peace of mind and the cam and lifters looked perfectly fine. Now I'm running the 224/224 and expect to see the same thing, no damage.