Cam ID??

[ChuckG]

So, just got back from the shop where my cam is being replaced with a 12-262-4. Amazing what crap my otherwise clean C4 accumulated between the radiator and condenser. Enough to fill a plastic grocery bag!

The original cam has few markings, but I can make out "GM20" between the lobes. Any ideas? The rebuilder said this motor had a "mild aftermarket cam" which it clearly does not.

Either way, it's going through his window tonight. Wish I was kidding. Not many miles, but too many years to take him to court for lying. Guess street justice will have to work.

The lobes at #2 cylinder, right up front, are really worn down. The others seem fine. Lifter is cupped too. Ideas what happened?

[c4c5specialist]

HI there,
No ideas what happened, but GM flat tappet cams have worn down with time.
I cannot tell you what those markings on the cam mean.
Sorry, c4c5

[ChuckG]

What's most troubling is I bought this motor as a fresh rebuild not 13k miles ago. Thought I could trust the mechanic. Learning otherwise. I can't imagine what other things I'm going to find that aren't so.

I'll take some pics and post them in my gallery. Most lobes are fine but Number 2's are just about gone. Very odd wear. Current shop thinks maybe the timing chain was somehow involved since it's closest. All valve springs are identical and look fine.

I've also been told those of us with flat tappet cams can benefit from adding at each oil change the crank case break-in stuff the cam companies make to supplement the zinc and other essential elements the blasted tree-huggers have secretly taken from our oil.

Next motor I buy will be a crate from GM! Long blocks are pretty reasonable. Jegs has them pretty cheap.