[grandville455]

The one pattern looks ok? But If u look at the other to the right it is quite far down the valve tip, I would go about .100 shorter also..

[Steve C.]

"If you are concerned with the location of the roller rocker sweep path and are convinced that it should be centered, there are steps you can take to improve the situation."

Rocker Arm Geometry And Valvetrain Alignment
A Detailed Explanation Of Valvetrain Alignment Goals

http://www.circletrack.com/techartic...y/viewall.html




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[llwta76]

Originally Posted by GR8ONE68

Ok, I've been thinking about this and I think I have it figured out. At first glance, I would think that the push rod is too short. But thinking it through, I think it has to do with which side of center the contact point (rocker to valve stem) is on. If the contact point is less than 90 degrees (3 0'clock if the rocker stud is pointing at 12), a shorter rod will bring the wear pattern closer to center on the valve stem. If the contact point were greater than 90 degrees, a shorter rod would push the wear pattern out closer to the exhaust manifold.

Is my thinking correct or am I over complicating it? Sorry for the hijack, but this post got me thinking about it.

Assuming a given engine w/the same valve train parts a shorter PR will move the contact pattern AWAY from the exh. side while a longer PR will move the pattern TOWARD the exh. side. Centering this pattern on the valve tip insures maximum valve guide wear while bad valve train geometry will cause accelerated guide wear.

[cutlas]

9.15" it is.
I re-checked my pushrod length using 9.1", 9.15", and 9.2".
9.1" gave me a pattern about center.
9.15" gave me a pattern just to the exhaust side of center.
These checks where with a hydraulic lifter pumped up and a week check spring.
My thinking is with my lifter pre-load added in, 9.15" should be just about wright.
Watching the rocker arm move through its stroke, 9.1" seemed to give a more even movement looking closer to 90deg at 50% lift.

Any one have a good set of 9.15" pushrods with at least .080" wall for sale?

[Skip Fix]

"Are you saying if your combo needs more lift all we need is longer pushrods?"

No I am not, just saying go measure one with several different lengths and dial indicator or pull op Pete's old article where they did that and it will more than just a few thou either direction. It does impact it just as swapping to different rocker brand can even if the ratio is identical as they use different roller tip diameters, and different geometry for the pushrod cup height vs fulcrum and roller tip. I have measured total lift while checking pushtod lengths and it definitely changes.

[78w72]

Originally Posted by Skip Fix

So how do you guys using hydraulic rollers do this?? Get an extra and make it solid?

Anybody?? I'm going to be installing a hydraulic roller cam soon, and I am confused as how to measure for correct push rod length. I was told I can't use a solid roller lifter as a "checking" lifter because it is way shorter than a hyd roller lifter, so what is the secret?

[Rodney R]

Originally Posted by 78w72

Anybody?? I'm going to be installing a hydraulic roller cam soon, and I am confused as how to measure for correct push rod length. I was told I can't use a solid roller lifter as a "checking" lifter because it is way shorter than a hyd roller lifter, so what is the secret?

I'm using all comp stuff for my build. For length, I bought a comp shelling rod and solid lifter. The seat height on the hydraulic is 2.49 and the Solid is 2.01. When measuring with the solid roller, I just add .48 to make up for the difference. I've heard that different companies may measure a tiny bit different, possibly giving you a variation of .1 on the measurements. Stick with one brand and you'll be fine. Just requires a little math

[78w72]

Thanks for the response. Some questions:
1. Is a "shelling" rod the push rod measuring tool?
2. Don't you mean subtract the .48" difference, to get the correct push rod length?
3. How tight do you make the rocker arm stud nut -- just to zero lash?
4. Do you have to compensate for the extra 1/2 (approx.) turn past zero lash that you do with hyd lifters? If so, how?