i have performer rpm heads and the instructions say that i may need +.100 pushrods so thats what i got. how do i make sure that their not to long?
thanks

Well, if they're too long your valves won't seat. I think you could check spring height and get an indication that way.

Put a dab of oil on the valve stem tip and install the rocker arm, pushrod and lock nut w/ball. Then turn the engine over two revolutions and remove the rocker arm. If the witness mark left by the rocker is not in the center of the valve stem then you have too short or too long of a pushrod. If its centered then the pushrod should be the right lenght but makesure you check a few others to be certian.

When I installed my RPM heads at first I used steel 1.5 roller rockers and they did not require longer pushrods but when I switched to 1.6 stamped rockers I had to get longer pushrods. Its a hit and miss situation, so I would check the geometry with normal lenght pushrods first and go from there.

If the pushrods are too long the rocker tip will ride on the inside of the valve stem edge.

how close to the center do they have to be? i just checked them and their slightly off center but very close.
thanks