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Rocker Arm/Valve stem interface

Posted: Fri Apr 12, 2013 3:05 pm
by Gene Gillam
While I wait for my pushrod length checker to come I took some time today to try to get an idea what my rocker arms were doing when they were pressing on the top of the valve stem. Let me start out by saying I've just had my rocker arm assembly rebuilt by Rocker Arms Unlimited (http://www.rockerarms.com/index.html) which included a new hard chromed shaft, new bushings and tips re-radiused so I'm hoping that its in good shape. Also, the valve stem heights are all the same.

I loosened all the rocker arms and marked the tips of the valve stems with a black magic marker (I'm pretty sure a dry erase marker would be better but I don't have one of them). I then rotated the crankshaft and set each rocker arm tight against the valve stem (i.e., no clearance) so I could (hopefully) get a pattern on the stem.

The following is what I got -

Re: Rocker Arm/Valve stem interface

Posted: Fri Apr 12, 2013 3:23 pm
by Gene Gillam
Based on what I'm seeing here I believe I need longer pushrods (I'm running a supercharger on an engine with domed pistons (originally carbureted) so I have two (2) solid copper head gaskets to lower the compression). Do the valve train geometry gurus agree?

Thanks,
Gene