Ok I have started getting the final parts for the solid roller going in the motor. I have a few questions.

First off the springs are going to be approx 210# on the seat and 525# open. Now I need a good set of rocker arms.

I have always heard very good things from Jesel and their rocker assemblies. I have been looking into the new S/S series shaft mounts but I have heard of some people breaking them. The guy at Jesel said they should be good for 250# seat pressure but no more. Also T&D makes them for LT1s as well, has anyone had any experiance with them?

Lastly do both of them work with the stock centerbolt Corvette composite valve covers?

What have you experianced with valve spring life? 10,000 miles? 20,000? And what springs were you using. I have heard both the Comp springs and the Isky 'Tool Room' Steel springs as being very good.


Thanks.

 

You might want to do a search on the screen name "kmook".... Ken had the new Jesel S/S shaft rockers and ditched them because of quality and design issues. My personal preference would be the T&D's. But I run pressures higher than you are quoting (springs from PSI) with the Comp Cams ProMagnums and no problems. I don't put many miles on the car, but the springs are now about 2 years old, with no problems.

A friend of mine had the high end Jesels, but I believe they only come in 1.7X and higher. He had to raise his stock F-Body centerbolt covers about an inch to clear the rockers.

 

You can get some stupid strong bolt in stud mounts instead. I would go with the Hi Tech Stainless Comp ones if you want really still rocker arms. They are ungodly still (52,000 Pounds/inch of deflection) But them in there on 7/16 rocker studs and you are good to go.

Bret

 

Is that deflection you are talking about a linear value? I assume so, at least to the point at which you begin to actually bend the rocker long arm or break it, so that would mean 1 inch deflection for every 52,000 lbs of force exerted.

Or, since we aren't talking about that large of a deflection, it might be better to state it as 2047lbs/mm deflection. Or, 2600lbs/.050" deflection. So, at max lift of around 500-525lbs over the nose of the cam, you'll see ~.010" of deflection. I guess that is the best you are going to get. So, in theory at least, on a .600" lift solid roller, you are only going to get .590" lift at the valve, and that doesn't take into account any stud flex or stretch, although the vector force on the stud w/ a rocker w/ roller fulcrum is in a nearly vertical direction, acting to try to pull the stud out of the head (the value of which is probably very minimal in comparison to rocker deflection) rather than in a horizontal direction (where you would run into more problems w/ stud deflection).

 

Excuse me if I'm wrong, but wouldn't the 525# be multiplied by the ratio of the rocker arm? 525 x 1.6=840# of pressure at the fulcrum (rocker stud), correct?

FWIW, I've had good luck with my SS Crowers w/ 7/16 rocker studs.

Mike

 

When talking about the deflection here, we are talking about the force exerted on the long arm of the rocker, which is equal to the force the spring is applying to the roller tip. So, the long arm of the rocker is seeing 500-525#'s of force exerted on it from the spring, BUT, the short arm of the rocker (where the pushrod seats in it) has to exert whatever the spring pressure is multiplied by the rocker ratio because of the increase in mechanical advantage (which is one of the main purposes of the rocker), the key is as you shorten the length of a steel structure, the deflection decreases in a greater than linear fashion.

For example, to keep things simple, lets say the long arm of a 2.0:1 ratio roller rocker is 1" long and the short arm is 0.5", if using the same spring at 500#'s open pressure, the pushrod is exerting 1000lbs to open the valve an compress the spring at this lift, but the deflection of the short arm is going to be much less than 1/2 of what it is on the long arm. I'm sure I could dredge up the formulas for why that is if it would be useful.

So, there would be deflection in the short arm as well, but would it be significant? I don't think it would add much to the total deflection but there would be some so that was an oversight on my part. The numbers would have to be plugged into the formula to know for sure what the value would be.

Sorry, I realized that I didn't respond to the actual statement of the rocker stud though. The force on the stud is going to be equal to the sum of the vertical forces applied away from the head, so in this case, using the values you listed, 525lbs at the spring and for a 1.6:1 rocker, 840lbs at the pushrod cup, so the stud is seeing 1365lbs of of pressure exerted on it and that doesn't take into account the additional forces due to the accelerating of the rocker according to the ramp speed of the cam which would increase the value even more. You can visualize it this way. Say you have a broomstick that is 4 ft long hung over your shoulders. The bucket on the right side of the stick has 50lbs of rocks in it. Your shoulders are the fulcrum. The bucket on the left has 50 lbs of rocks also, both are at 2 ft from the fulcrum or pivot point. So, you want to move the left bucket to 1 foot from the fulcrum (move it in 1 food towards the center of your body), you now need 100lbs of rocks to keep the buckets balanced. BUT, you are now carrying 150lbs of rocks to do that rather than 100lbs as before.