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Originally Posted by scottj
uhh... one minor note: Lifters are convex on the face and cam lobes are tapered...that is why they rotate.
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Goly gee
I always assumed they were flat.... least ways they looked flat to me. I guess I never gave much thought to why they rotate. I'm going to have to go over to my sons. He alway has something appart.
However, no one has yet to tell me what needs to wear to a final propper fit, when breaking in a cam.
I understand the ZDDP thing, but the lack of it can cause old engines with 50K, 100K miles, and more wipe a cam. It is not just break in.
My son fired up a rebuilt 350 chevy - all new parts, including high lift high durration cam with heavy spings. He fires it up with load pipes and keeps the rpms up for cam break in. Half way through the cam break in he hears it knocking. He shuts it down and calls me. I listen to it definate knock and the
oil pressure has dropped off to about 15 psi, which he didn't notice from under the hood. Checked the
oil and it had about a half gallon of gasoline in it. The mechanical fuel pump diaphram was bad (brand new pump). Pulled the engine appart and the rod bearing gaps got worse the farther they were from the
oil pump. The front two had a good 0.030 clearance. The point to this whole story is this fact. The cam was not harmed. You couldn't get a worse lubrication problem on cam break in than this and that cam shaft held up.
Now another cam fails on start up, with good oil in the engine. I'm finding it hard to believe it was because the rpms were not in the magical range.