boese1978

My scorpion roller rockers were bottoming out on the rocker stud nut. Scorpion suggested ( they are horrible with returning calls etc) a longer push rod. The push rods I am using give/ gave me spot on witness marks on the top of the valve. How much longer a push rod would be adequate while avoiding changing the geometry of the valve train? Suggestions and thoughts and even part numbers suggestions are welcome-Thanks All

64Rocket

I think you need to mill the rocker arm pad the thickness of the the guide plate.

Gene

Fred Kiehl

It depends on how badly they are bottoming out, and which side they are bottoming out on. If they are "just" touching at full travel, I would think a shorter pushrod would be in order. If they are "just" bottoming out with the cam on the base circle, a longer one is the ticket.


A tenth of an inch either way should not affect your witness mark very much.


Do you own an adjustable pushrod for measuring the length? You can use weak springs (springs from fuel pressure regulators work great) on one cylinder to allow you to adjust the length checking pushrod until the rocker arm does not touch the nut in either direction. Give yourself a little extra space for heat expansion. The adjustable pushrods are available from your local speed shop, Jegs, or Summit Racing. Once you have the geometry worked out with the adjustable pushrods, you can order rods to the correct length. That is how I did mine on the 454 in by 91 OCC.


Measure the pushrods you have now, and order the ones that allow you to go plus or minus of that.


http://www.jegs.com/p/JEGS-Performan...58609/10002/-1

boese1978

Thanks for the input- here's a pic....you can see the shiny wear mark on most of the underside of the rockers. I think I am going to grind the replacement rockers (3of them)to clear and re-use the ones that were " auto clearanced" by being in use just to save some $$$ as opposed to a set of new rockers and pushrods. The push rods I have now are Engine Pro 5/16 x .083 and they are 7.900 inches long.
Gene- what you state is not clear to me, after looking at the pic what do you say? Thanks you two, I appreciate the input.

64Rocket

So where you bolt the rocker stud and the rocker stud holds the guide plate. That surface is what you mill down the thickness of the guide plate. Approximate 75 thousand .
that way the plate and stud set lower and the rocker should clear the stud. So if the heads are still on the engine, I would do like you said, clearance the rockers in that area. Be sure to clean the shavings off and make sure none get in the rollers. Then re-oil them. JMO

Qwik71442

You can use this adjustable pushrod length checker to try different lengths to figure out what will work for you. These are the ones I use they make it real simple. It has increments by how many turns you lengthen it from the bottomed out position. You can buy the size area rod you need or the set if you need them. Here is the individual one that should be a good start.

http://www.jegs.com/i/COMP-Cams/249/7703-1/10002/-1