Picked up a Comp Cams pushrod checker. I would like to know when to go longer or shorter with the pushrod length depending on the contact pattern on the valve tip. Example: if contact pattern is towards rocker arm do I go shorter or longer? vice-versa? My former engine builder screwed up and put two differnt sizes in my engine .050 difference. I have H.S. 1.5 roller rockers. Thanks for your time.

Picked up a Comp Cams pushrod checker. I would like to know when to go longer or shorter with the pushrod length depending on the contact pattern on the valve tip. Example: if contact pattern is towards rocker arm do I go shorter or longer? vice-versa? My former engine builder screwed up and put two differnt sizes in my engine .050 difference. I have H.S. 1.5 roller rockers. Thanks for your time.

Shorter if it's toward the rocker stud.

On that note, how do I determine the pushrod length from scratch before there are any wear marks? I just assumed the XR264HR cam and magnum roller tip rockers would be designed to use the stock pushrods, but now I'm curious.

Tillertracker, use a pushrod length checking tool, most places that sell performance parts will have them. Check Summit, Jegs etc.. Basically all it is is a threaded adjustable pushrod, use it in place like a regular pushrod and measure the length, then order pushrods to that length.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by 68blkbrd:
Picked up a Comp Cams pushrod checker. I would like to know when to go longer or shorter with the pushrod length depending on the contact pattern on the valve tip. Example: if contact pattern is towards rocker arm do I go shorter or longer? vice-versa? My former engine builder screwed up and put two differnt sizes in my engine .050 difference. I have H.S. 1.5 roller rockers. Thanks for your time. </div></BLOCKQUOTE>

That may or may not be a screw up by your previous engine builder. If the cam lobes are different (not a single pattern cam) then it is possible the intake and ex. pushrods are different lengths.

The roller tip needs to be on the inside 1/3 of the valve stem at 0 lift. Throughout the lift you need to inspect the roller tip and see where it rides. It should go about to the same position on the outside 1/3 of the stem at about 1/2 lift, and at full lift it should come back towards the center of the stem.

If the tip of the rocker is too close to the inside, them the pushrod is too short. If it starts too close to the outside edge, the it is too long.

Just mock it up, and check!

Either use light "checking" springs on the valves, or a solid lifter. I put a light dab of primer on the valve head, installed the rocker arm, rotated the motor a few times, and looked at where the primer was removed. With an adjustable pushrod, just adjust it and repeat the process until the pattern is centered (or wherever you want it), remove the rocker and measure the pushrod to find out what length you need.

Remember to clean off the remaining primer!