Wiping cam lobes help.

[VadersV6]

In one of the 348 threads on this subject, I was talking about heat treating and tempering. Doesnt sound like any big deal, but it IS a big deal. Ive got alot of experience with this stuff and can tell you....If there is a hardness difference between the lifters and the cam of the slightest order, you will wipe lobes. The reason the factory cams lasted is because in order for your parts to be accepted by GM and the warranty people, you have to pass extremely strict quality control tests...especially with a cam. If the hardness/temper isnt EXACTLY the same between the lifters and the cam, the cams in the test motors wipe out, and mr. wiped cam maker doesnt get the big contract. Most aftermarket cam manufacturers do not have much of any QC program cause it costs more to test every cam then it does to make every cam. And these cams are so cheap, who is going to put the time in to check hardness on every batch? I would bet none of these guys even have a hardness tester. Get your cams and lifters from an OEM manufacterer, and the same manufacturer for both cams and lifters. Just because company X made cams for factory motors doesnt mean they didnt grind performance cams as well.

 

[BJM]

For gears, it is very normal to ensure that the hardnesses are in fact different. If they are the same they tend to fret much more (one surface transfers to the other). I do however agree that the OEMs standards will require the hardnesses to be very accurate, if not the same.

As far as lifter spacings go, on my engine the pushrods at idle would spin between .75 to 1.5 turns on each activation while #3 exhaust would chug away at maybe 1/8 turn each time. The cam was fine though, no loss of lift.

When I replaced my springs, I made a valve spring measurement scale and put the softest spring in that location. I also measured the stock springs and found something interesting. Based on the service manual specs and the spring size (active coils, wire diameter, etc.) that the factory installed spring cannot meet the factory manuals specification. The factory seat pressure is below spec when the spring force is in spec at full lift. So the factory intentionally softened the springs, maybe to save on warranty claims?