GTOguy

Another supporter of moly lube over here. Interesting on the flat cam thing. Today, it's mostly due to poor quality camshafts that aren't hardened properly, as well as the newer PC engine oils designed to not destroy cat converters on worn out sh!tboxes. Back in the late '70's, a lot of Chevy cams would lose just one lobe, I remember. The procedure that I saw at independent shops was to simply replace the cam and lifters. No further disassembly. A gent I work with worked at a GM dealer from '69 to about 1980, and said that the cam lobes were flame hardened, each by their own individual flame, and that sometimes a torch would go out and you'd get many cams with a single un-hardened lobe before the problem was discovered on the line and the torch cleaned and re-lit. Don't know if this is the truth, but one of you gents probably do! Makes sense to me, as I saw a lot of flat cams back then on the 305 2bbl engines that had only one bad lobe...the others had no wear at all. In modern day cam failure situations, a total teardown, cleaning, and inspection is mandatory, IMO....all that metal went somewhere.

cardo0

Coincidence u mention stock Chevy cams loosing a lobe GTO. When i pulled the stock L-48/929 cam from the "target motor" i got in the car it had a wiped exh lobe. Engine seemed to have a "miss" that i was unable to tune out of it. This was an early 90's crate motor - Chevys $1000 350". Car drove fine though, but it was a dog for sure.

GTOguy

Ran into one fairly recently myself. It was a cherry, low mile '79 Monte Carlo, one of the first small ones. Nice car. Ran rough with poor power. All cyls. checked ok with a static compression test. Found out doing a running compression test what it was: flat exhaust lobe on number 6 cylinder. Was a 305 2bbl, original engine. Interesting.

MikeM

GM cut a big manufacturing cost hog in the butt in the the '70's with their soft cranks, cams, thin head castings, manifolds and using steel that would corrode easily plus removing in plant corrosion protection. Quite a little mess they created.

Then they turned around and paid out all the savings (and probably way more) in warranty costs to fix/patch the stuff.

And then along came Volkswagen, Toyota and all the rest.

Pop Chevy

GM would pay for the cam, lifters and gaskets and flat rate time. Anything else was on the owner, after that we would shove em out the door. I don't remember if they covered an oil change, that was another bay.

Westlotorn

A couple note to share. Cams are hardened on the lobes about 3/8 of an inch deep so even if a cam goes flat the hardness can be checked and will still be there. It is not a surface hardness.
Cams are hardened in ovens, many go in at the same time. The temps they reach will harden the entire shaft, bearings and all. Knowing this if one lobe is hard they are all hard. If you find a soft camshaft the entire shaft and all lobes will be soft.

The major rebuilders would kick out between them about 20,000 engines per month and in the day 30% of those would be 350 Chevy's. When a cam went flat they pulled it and replaced it and the engine continued its life under full warranty with all the metal from the old cam in place. Not perfect but done Thousands of times and it sounds like the GM dealerships did the same thing.

I have seen many engine failures due to the installer using Scotch brite type pads to clean parts, the material ends up in the bearings and causes failure. I never witnessed a engine failing due to cam lobe material causing bearing failure. I do agree there is metal in the engine but the particles must be so small they don't cause harm.

GTOguy

I would think any size of metal particle would be bad news....perhaps the stuff got caught in the oil filter quickly, or settled in the pan, flakes too big to go through the pick up screen. Same experience here, though: have seen many cam/lifter replacements and out the door, and the engine lived happily ever after. Seen many more failures due to improper repair techniques, as stated, with debris from pads, shavings from machine work, and excess silicone sealer crudding up the works and causing parts failure.

MikeM

Sounds right. Thanks.