Triumph TR8 V8 Rocker gear

Triumph TR8 V8 Rocker gear
What is Lifter Preload?
Lifter preload refers to the position of the pushrod seat in the lifter (cam follower) when the engine has been assembled and the lifter is positioned on the heel of the cam. Lifter preload must be checked whenever a non standard component which alters the distance between the rocker arm and the lifter - such as a high lift camshaft or performance cylinder head - has been fitted. Incorrect lifter preload will cause poor running, premature wear or, at worst, engine failure.

Check the lifter preload as follows:

With the lifters empty of oil, assemble the rocker shaft & pushrod components, making sure there is no wear in the rocker shafts, rocker arms & pushrods.
Checking each lifter in turn, positioned on the heel of the cam, measure the gap between the pushrod seat and the bottom of the circlip groove. There must be a clearance of .020" minimum and .060" maximum at this position.
If the clearance is greater than .060", use pedestal shims (603734SH) to decrease. Remember to use equal thickness shims under each pedestal of a shaft to avoid distortion or breakage.