The factory 20 lb adjustment is also in conjunction with having the stock bottle neck rocker studs.
The stock factory non RA4 lifters have a plunger travel range of .120”.
This gave the factory room to play around with head gasket thickness and and tolerances in applying the valve job while allowing for heat expansion of the valvetrain and valve recession during the life of the motor while still having no lash take place to make for valvetrain noise and to allow the valves to close and seal.
The 20 ft lb adjustment on average puts the lifter travel right in the middle pretty much of its .120” range when a hydro lifter will perform its job as intended.
Things are a bit more critical with the factory RA4 lifters as there plungers only have .060” travel range if I recall right.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
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