[DeTomaso] rocker arm adjustment

Paul - Home thedrol at pobox.com
Mon Jun 14 11:17:42 EDT 2010


I can think of a few reasons why they could be loosening up.

1. the set screw is backing off
2. the cam lobe is wearing down
3. when initially setup, there was oil in the hydraulic lifter that has 
now bled away, ie the lifter was pumped up and now isn't.
4. the tappet pre-load was set hot and now is being measured when cold.
5. the pushrods are bending and now they are "shorter"
6. when the tappet pre-load was set the tappet wasn't on the base circle 
of the cam, but it is now.

You may need to mark your set screws.  It is easy to check the pushrods 
for straightness.

Paul
#9270

Justin Greisberg wrote:
> question for cleveland experts -- 
> 
>  
> 
> I have stock block, crane linked hydraulic lifters, harland sharp roller rockers.  i adjusted the rocker arms by going one valve at a time with the engine on a stand to be sure I got it just right.  when I recently changed head gaskets, I noticed several of the pushrods were just a tiny bit loose, as if I had set the rocker arms a little too loose.  i reset them all, and next time I changed the head gaskets (dont ask) a few weeks later, I noticed the same thing again.  i gave up and have run the engine a bit and it seems fine.  any thoughts on the tiny-bit-loose pushrods.  (tiny bit loose means I can spin them easily and there is even a tiny bit of slack in them.  normally when I adjust, I tighten the rocker set screw until the rod no longer spins by fingers, and then 1/2 turn more.)  justin
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