cam lobe wear and piston scuff pics

[RAPTORFAN85]

I am in the process of swapping out my stock cam for a perf. cam and found some wear on the stock cam that I didn't seem to notice when the stroker was built. The cam only has 42,xxx miles on it, 40,000 stock. The tips of some of the lobes are very rough and pitted and it looks like the hard facing is coming off. The same thing on the lifters. Could low ZDDP oils have caused this?








When I built the stroker there was some scuffing on the stock pistons too, luckily I take pictures of everything
I didn't think much of it at the time because the block was being bored over.




To me this looks excessive for 40,000 miles, what do you guys think?

I used to run standard over the counter Amalie oil for the 10,000 miles that I owned it(before I knew about ZDDP) and I can't say what was run before that...
I will be running VR-1 from now on.

So could the oil be causing this wear?

[RAPTORFAN85]

anyone?

[dwg86]

No idea...sorry.

[gradon]

Would the scuffing be from having too much piston clearance in the bore, thus is rocking a bit, or could it have been too tight? I wonder if a coated skirt piston would've helped.

[RAPTORFAN85]

Would the scuffing be from having too much piston clearance in the bore, thus is rocking a bit, or could it have been too tight? I wonder if a coated skirt piston would've helped.

Thats along the lines that I was thinking (to tight in the bore)
Also the pistons are aluminum so I thought maybe they would show more wear because they are softer then the block...

[Exos]

Are these pics of your old stock pistons, or your stroker pistons?

[RAPTORFAN85]

Are these pics of your old stock pistons, or your stroker pistons?

Old stock pistons.

[Exos]

How could the piston to bore clearance be too tight or to loose in a stock engine from factory?

About the cam, if the wear appeared after the stroker (?) , what valve springs/rockers are you using? And what oil did you use since the build and for break-in? Did you use new lifters when you built it (I'm sure you did)?

I have more questions than answers... still learning here and in the process of building mine.

[RAPTORFAN85]

How could the piston to bore clearance be too tight or to loose in a stock engine from factory?

About the cam, if the wear appeared after the stroker (?) , what valve springs/rockers are you using? And what oil did you use since the build and for break-in? Did you use new lifters when you built it (I'm sure you did)?

I have more questions than answers... still learning here and in the process of building mine.

That's what I am wondering. The wear was on the pistons was on a stock motor. It doesn't seem right that there was that much wear on a stock engine.

I didn't assemble the stroker the first time, so I can't say for sure if the cam looked like that when it went in. The mechanic said the cam was good and I took his word for it because I work with the guy and I know first hand that he is a good wrench. I run the stock jeep valves, springs and retainers with yella terra 1.7 roller rockers. The lifters were reused and put in the same holes that they came out of.

I used Amalie oil and some EOS for break in and straight Amalie after that. I think that the oil might have been the problem with the cam. This was before I knew about ZDDP and the likes. VR-1 is what I will use from now on.

[Exos]

I used Amalie oil and some EOS for break in and straight Amalie after that. I think that the oil might have been the problem with the cam. This was before I knew about ZDDP and the likes. VR-1 is what I will use from now on.

I disassembled my project engine, a 93, a few weeks back, and the cam was in exellent condition, almost no wear. There must be another factor than just the oil. If it was just the oil, then almost every 4.0 camshaft would be in a bad shape, stroker or not.

[SilverXJ]

I've seen auite a few late model cams that have looked like that and worse. One was from my orginal engine, which I got at 28000 miles and babied, the other was off a 2002 (IIRC) TJ with 30k miles, and the other was out of my donor block.

[Exos]

I would like it to be only an oil composition issue. Then we'd not need to worry about spring rates, oil flow, cam break-in and other factors. But I'm still not conviced.

From the look of those pistons, something was not going smoothly in that engine, and the wear on the cam had probably begun before the build.

[1bolt]

the wear on the stroked pistons is not normal at all. Is there a burr on the bottom of the cylinder wall from the honing process? Do all the pistons look like that? It looks like excessive piston to wall clearance because it appears from the pics that even the land area immediately below the oil control ring is scuffed.

The cam looks like it didn't dig a fresh set of lifters, and the iron is starting to delaminate, the lifter faces look peened which could be excessively light(or worn out) springs, loose preload, worn valve train components (too much slop) low oil pressure or pinging, if the lifters are "tossing" that would explain the pitting on the lobes and the peening on the lifter face...

Metal from the valve train/lifters or Cam lobes contaminating the oil would contribute to accelerated ring wear which would lead to pistons rocking.

A low ZDDP oil may very well have contributed to this as the ZDDP is important not just on the cam/lifter inteface but also all the sliding friction components (valves rockers, push rods, distributor, oil pump and timing gear teeth etc), but reusing a used flat tappet cam with new lifters that probably wore excessively before they were totally broken in would be my first guess.

[Exos]

the wear on the stroked pistons is not normal at all. He said it's the old stock pistons

The cam looks like it didn't dig a fresh set of lifters He said he used the old lifters

[1bolt]

you're right my bad, I missed the post where he clarified. that second piston pic looks like a different piston at first blush