Rocker shims = NO rocker shaft oiling

Bewy said
Anti pump up lifters [ APUL ]. Properly designed APUL do NOT use a paper clip circlip, which is what stock lifters have. They use a much stronger circlip to stop the lifter pumping apart due to pump up.
The minimum pre-load idea came from hot rodders & there is a very good chance that the engine could come to grief. Russian Roulette with a 6 bullet revolver & 7 bullets....
As I said earlier in this thread:
- using strong enough valve springs prevents pump up.
- you have about 0.150" of lifter plunger travel. There is no need to set the pre-load so tight for the reasons stated above.
Click to expand...
Every,..EVERY engine w/hydraulics I have ever assembled where I was setting preload, I set to .020-.025". I have NEVER had a single tappet or cam failure, ever. Only one cam, a 292°MP SB cam, lost a lobe after 15yrs. of street/strip use, a 6bbl mill that had seen routine shift points of 6,900-7200rpm in trying 4.10,4.30,4.56:1 gears out back.
No spring "prevents" pump up, it minimizes it, and the tendancy is directly a function of valve/retainer/spring mass, ramp rates, & oil feed/pressure.