RROLDSX

OK, time to fess up. I was too cheap to buy HS rockers. That being said, I don't know for certain they would help. I installed the Comp Cam rocker studs and guide plates. Using an adjustable push rod, I measured a 9.800 push rod length to achieve optimum valve tip geometry. To do this I used an old lifter with some washers to limit lifter depression to 0.045". The problems lies when I adjust for any lash at all, the valve depresses of the seat. One turn on the rocker arm adjustment equals about 1/10" of an inch valve opening. With all I've read about valve bound and so forth, Is this normal?

Thanks,
Randy

coppercutlass

I had the same thing happen. What's going on is the pad on the heads has not been milled to accept the extra .060 of the guide plate. I ran pushrods about .100 longer. No issues. I have accidentally ran em .200 longer for years with no issues. I'm running the prw rockers with no issues. 2 seasons of street and strip action. I think you also need to check for proper length with the rocker being used.


Edit. Whats going on that alarms you. Why did you limit the travel of the lifter. if the lifter is solid then thats why the valve is opening. When you check for lash you get it to zero then give it the amount of turns you need. usually half to 3/4 past zero. The lifter will compress appx .045 to .060 with half to 3/4 turns. Most companies have figure with the correct thread pitch for those figures to be pretty accurate. If the lifter has no compression than yes the valve will open.

RROLDSX

Even with the lifter free (also empty) the valve opens. I set the lifter depth to establish how much the valve opens when the lash is adjusted one turn. I ordered 9.800 push rods already but they may be too long as well. This is a 455 with E heads milled about 10 thousand using Felpro head gaskets. I think what you say makes sense but now I'm not sure what push rod length to use. Either way the geometry will be off. Will the strength of the valve spring depress the lifter plunger lower in the lifter when it actually pumps up?

coppercutlass

The lifter should compress as is. You sure the rocker arm is not binding up on the stud and when you are tightening it ., its compressing the valve springs. By binding up i mean the stud might be too tall due to the added height to the stud pad as i mentioned before.

i had this issue when i bought my push rods. i didnt factor in lash and when i lashed the valves / lifter pre load the rocker was binding up on te stud as the 40-60 thou in comression was enough to bind it on the stud. The cheap fix was longer pushrods. Pattern was slightly off center but it was a small pattern that did not sweep across so all was good.

RROLDSX

While adjusting the lash I was spinning the push rod with my fingers until it was tight or stopped spinning then I adjusted the rocker one full turn. It appears by then the lifter was too far depressed and the valve spring was compressing instead. In order to get around this I tried locking the lifter at 0.045" depression which essential did the same thing. This time I just adjusted the rocker until there was no up and down play (but still spins) and set the rocker one full turn and no valve movement was detected. I am still using the 9.800" adjustment so I believe I'm good to go once my lifters pump up. Thanks again Copper for staying with me on this.

coppercutlass

I would not go one full turn. I think 3/4 is max imo . i usually just go half turn then tighten the set screw and snug the nut again. but yes you are only supposed to snug the rocker arm nut until you feel some drag and there is no slack.

64Rocket

Make sure the rocker is not touching the rocker stud at the bottom.
I tighten until the push rod has drag on it, then tighten 1/4 turn more and done.

Gene

RROLDSX

Yep, thanks Gene but why only a quarter turn?

64Rocket

The way you did your measurements. I don't think you have the right length push rods.
I put the lifters in on the base circle of the cam, set the checker in and put the rocker on. Adjust the checker until I get the pattern I want. And rocker does not ride on the stud at the bottom. pretty simple.
I only use a 1/4 turn because I only want 20/25 thou down from the "C" clip.
That is what I do, for me it works.

Gene

RROLDSX

I've got my measurements and geometry figured out. I was just over tightening the finished sizes to the point of prematurely opening the valve. I think keeping the lash adjustment to 1/4 turn might reduce the possibility of bending those long push rods. Thanks again.