roller rockers

[kuda4]

I have Crane roller rockers on my 340 w/X heads, how much pre-load do I give once the rocker is in contact with the push rod?
Thanks Merry Xmas

[billyclub]

Kuda,
Hydraulic lefters use about .040 preload, which equates to about 1/2 of a turn past the contact point

[bandit340]

I have the same setup,and I just go a 1/4 turn after you cant spin the pushrod anymore. Those Crane Rockers have course threads.Chamfer the oil hole in the shaft a little more and use the correct springs.you can always tighten them up a little more.10 to 15 thous. preload frees up a Little more HP.I noticed the difference from the standard old fashioned way.

[PRO]

Anytime I adjust lifter preload I take into consideration the duration of the cam,if you put a vaccum on a running motor and adjust the valves youll find higher vaccum with less preload which results in better low end response especially with big duration and overlap. .010 is a minimun number, anything less and the pushrods will fall out as the lifters bleed down overnight. Chrysler recommends .030-.060 but thats a stock cam with limited rpm potential. Also you will have a better cam break in pattern with less preload as the lifter spins easier.....PRO...