Cam Button

Buick Mark

Active Member
It needs to be there, a captured needle bearing bumper is available which is what most people switch too.


Active Member
I know the factory put them there for a reason but I'm trying to figure out why? Most other flat tappet cam engines don't use one. It seems just like it wouldn't be needed and it just fills your oil pan with aluminum filings from the cover.


The oil.pump and cam sensor drag keeps the cam rearward against the block above idle rpm. The button keeps it against the thrust only at idle and slightly above. A high volume (not pressure) pump keeps it rearward better than a stock pump (more drag). A FULLY oil galley modified engine let's the cam walk more at low rpm due to less pump drag.
A high PRESSURE pump doesn't help the walk much at idle, because the higher pressure spring doesn't come into play until the rpm is up.
Covers can be saved with a bit of heliarc weld where the button rides, followed up by a smoothing pass in a mill, or artful work with a small disc sander. Or I have seen a bad cover fixed with epoxy and a thin steel washer of an appropriate thickness and diameter. I have no idea how long it was running like that before it came in for a complete rebuild. I welded it.
Often, by the time the cover is worn from the button, the oil pump housing is worn beyond service limits too. Check that before spending time on the button area...