Adjustable rocker pushrods

It can be a pain, but, you need to trust your results providing you are sure you are doing things right. It is common for shorter pushrods to be needed for different block heights, different cylinder head casting deck surface results, different head gaskets, different cams and/or lifters, and differennt rocker assemblies. For socket (cup) type designs, you need to also take into account the design of the cups. Using the 505 deal I'm doing now as an example... I like Comp Cam's pushrods, and the catalog says a set of 9.030 is perfect for an RB. Comp uses the length of the pushrod from the tip of the ball to the bottom of the cup for a length. So, I use my set-up pushrods with the cup, and with 2-3 threads showing on the adjuster, cold lash set at .020", I come up with 9.142. This engine has a 10.700 deck height, and the Edelbrocks have been milled .040, plus a .043 thick gasket, and Crane 1.5 Golds. Now, my set-up pushrods have a cup end that started life as a /6 mopar pushrod made by Sealed Power. So, my dimension is total length, andd I need to subtract the depth of the cup to match what Comp says. The cup is .142" deep. So really, I need 9.00 in Comp's way of measuring to be perfect. The 9.030 will be fine, because there is plenty of thread room to fit .030 more and still have full thread engagement when everythign is hot and expanded.

In your case, you want to make sure you have enough for a little preload. Check with Federal to be sure what they want. Most anti pump up ones want little preload. But they can tell you to be sure. Just trust what you come up with so long as you are doing it right.