Re: stamped steel rocker arm delection
 

Approved by Glendora.

Re: stamped steel rocker arm delection
 

good to know,,,thanks for the replys ,,good bunch of racers gmonde

Re: stamped steel rocker arm delection
 

If you can get a bigger pushrod in there, and it is legal to open up the holes in the head, you need to go with a 7/16" x 0.125" wall, at the very least you need a premium brand 3/8" x 0.125" wall 4130 heat treated pushrod. You honestly cannot get too stiff a pushrod in a race engine.

Re: stamped steel rocker arm delection
 

Alan, in a stocker engine with a floppy rocker arm, is the extra stiff pushrod that important?

To quote the cliche, "You are only as strong as your weakest link." If you determine the effective stiffness of the rocker arm and then the stiffness of the pushrod, the pushrod is around 20 times more stiff (or stiffer) than the rocker arm. And since these are essentially two springs in series, the lower stiffness drives the total stiffness of the system.

Re: stamped steel rocker arm delection
 

i did go from a 5/16 to a 3/8 chromoly push rod .080 wall,i did do some r&d on the rocker arm with several versions of welded rockers,you can get the rocker to stiffen some but you end up adding so much weight to the valve train it would be counter productive it looks like the bottom of the rocker wants to spread out ,,but if you put a rocker in small tool vise, you can see how it flexes real easy with little turning effort ,,its amazing that how much they flex but the breakage is low gmonde

Re: stamped steel rocker arm delection
 

Pushrod stiffness prevents the pushrod from flexing, and putting its own flex and dynamics into the valvetrain. The rocker cannot even begin to do the damage the pushrod can, the pushrod becomes a spring that flexes and surges, then transfers all of that into the rest of the valvetrain.

Unless you try to make the valve end of the rocker out of lead, you're not going to make the rocker arm heavy enough to make rocker weight into a negative factor.

Re: stamped steel rocker arm delection
 

One of my friends that worked at comp cams told me you can't make the pushrod side too stiff or the valve side too light.

Re: stamped steel rocker arm delection
 

Greg, I agree with this up to a point. 90% of the people we talk to are not talking about stocker level stuff. Their experience is with high lift, high spring rate stuff. Talk to Sacha at Trend. They have some cutting edge stuff right now and use a Spintron as well as some other tools for R&D. My 1.72 intake valve will take a different spring rate and pushrod diameter than a 2.02 cylinder head. It just doesnt automatically cross over....

Wade O

Re: stamped steel rocker arm delection
 

Hey Wade have you put your stuff on a spintron? If so how about sharing some of your results.

Re: stamped steel rocker arm delection
 

Exactly what Wade said, different combo might like different things. And yes it is
possible to (over pushrod) a engine..