If you have hydraulic lifters, you need to pay attention to what the
lifters are doing. They will bleed down if you keep tightening the nut,
and you can still turn the pushrod, even though you have tighened them
WAY too far! I think this is your basic problem, since you mentioned
having to turn the nuts an extra 4 turns. Hopefully you didn't mess up
anything...you probably just have them about a half turn past bottomed
out, so the valves will only be opened a little bit extra, and shouldn't
hit the pistons.
I use a similar proceedure to what you used, but I make sure I have
slack by moving the rocker arm up and down. If it moves freely and
rattles, then there is slack. Then, I carefully tighten slowly till the
slack goes away (can't rattle it up and down anymore), then add the 1/2
turn preload.
I run thru the firing order...put #1 at TDC (but not firing), then
adjust the two valves for #1...rotate the crank 1/4 turn, then do the
next two valves (#8), then another 1/4 turn and do #4, etc. I think
this is more reliable than doing half the valves at once...besides, with
a longer duration cam, you want to be sure none of the valves are
starting to open when you are adjusting them.
I don't adjust hydraulics with the engine running...it's too messy and
hard to tell what's going on. In fact, I usually never adjust
hydraulics except when assembling the engine. They should stay adjusted
forever, or at least until the camshaft wears out.
Jim
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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