Quote:
Originally Posted by JFP in PA
Go back and reread Jake's comments about the crown finish and hardness. If the face against the cam is not hardened, and with a crown to promote rotation, the crown will wear into a mushroom shape, making it impossible to remove, while also tearing up the cams.
Anyone that has ever wiped out a flat tappet cam will know exactly what he is referring to.
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Exactly.. I don't give a damn about the contact surface to the valve stem, as long as its the proper hardness.
The crown that follows the cam lobe is whats absolutely unforgiving and effects lifter surface speed and reset as the cam lobe wipes across it. This is a critical dimension and one thousandth of an inch may as well be a mile.
FYI- I have seen brand new lifters come with improper crown radius, and we have to check every single lifter that we install because of this. It sucks, but we save our asses every time that we do it.
Assume nothing, quantify everything.