Rocker Stud Girdle Benifits

[statsystems]

Way back when I was just a kid at Edelbrock, I got one of the first Jomar girdles for a BB Chevy. This was probably in 1972. I had a General Kinetics cam with 800 lift. Without the girdle, it had 770 lift, and with the girdle it had 805 lift. Pretty big deal, then and now. You do not want to know about the piston to valve clearance !



JOE SHERMAN RACING

I'd like to know about the P/V clearance.

[Zmechanic]

just remember to check the lash after tightening up the girdle as it will sometimes pull the studs one way or the other.

+1 to that, especially factory iron heads that were retrofitted for studs. Loosen girdle, check lash, adjust lash, tighten girdle, check lash, remember if it tightened or loosened, loosen girdle, compensate a little, tighten girdle, check lash, rinse repeat. It's actually much easier on the cheaper SBC Jomar girdles where U-bolt also locks the adjuster so you can loosen them only one at a time.

[bigjoe1]

About piston to valve clearance. I have got away with much closer than most people would dare to even try. Back then, I had 040 on the intake ,and 080 on the exhaust. Now on my own serious drag race engines, I run as close as 015 on the intake, and 060 on the exhaust. Proceed at your own risk



JOE SHERMAN RACING

[GARY C]

I run 7/16 stud on everything so I never worried about a girdle on hyd flat cams partly because the few dyno test I saw with and without lost power with a girdle which makes me think they increase harmonics, I have also seen solid rollers break studs even with a girdle which also makes think harmonics, although the girdle does hold everything together making it a safe choice.

I always wondered if it would be worth putting something like a Teflon sleeve on the nut and modifying the girdle to fit would help but never tried it.

You need to give a lot more info because I've never herd anything of the sort.

Base line the engine, install girdle, loose 5 to 7 hp and tq, remove girdle regain hp/tq, install girdle loose 5 to 7 hp/tq, remove girdle....rinse and repeat.

[GARY C]

just remember to check the lash after tightening up the girdle as it will sometimes pull the studs one way or the other.

+1 to that, especially factory iron heads that were retrofitted for studs. Loosen girdle, check lash, adjust lash, tighten girdle, check lash, remember if it tightened or loosened, loosen girdle, compensate a little, tighten girdle, check lash, rinse repeat. It's actually much easier on the cheaper SBC Jomar girdles where U-bolt also locks the adjuster so you can loosen them only one at a time.

Thats why I always did my solid roller lash at full engine and oil temp, it was more of a pain but I would go through the drivers side thoroughly and then run the engine again before going through the passenger side

[statsystems]

About piston to valve clearance. I have got away with much closer than most people would dare to even try. Back then, I had 040 on the intake ,and 080 on the exhaust. Now on my own serious drag race engines, I run as close as 015 on the intake, and 060 on the exhaust. Proceed at your own risk



JOE SHERMAN RACING

That had to be knocking the carbon off the Pistons!!!!!!

That is razor close. Damn.

[MadBill]

With the right shape exhaust valve reliefs, it could be a desmodromic assist thing..

[bigjoe1]

It is all possible if you have faith in the cam lobe design-- NO VALVE BOUNCE OF VALVE FLOAT !




JOE SHERMAN RACING

[MadBill]

And no getting first gear when you're going for third!

[Walter R. Malik]

I run 7/16 stud on everything so I never worried about a girdle on hyd flat cams partly because the few dyno test I saw with and without lost power with a girdle which makes me think they increase harmonics, I have also seen solid rollers break studs even with a girdle which also makes think harmonics, although the girdle does hold everything together making it a safe choice.

I always wondered if it would be worth putting something like a Teflon sleeve on the nut and modifying the girdle to fit would help but never tried it.

IF putting on a stud girdle lost power ... your cam was probably to big.
Those are the only times I have ever seen a girdle be a detriment.

Explain to us all how a stud can break when in double shear, where the STUD itself or the installation was not the problem.

[GARY C]

Explain to us all how a stud can break when in double shear, where the STUD itself or the installation was not the problem.

None of these were my engines so I could not tell you the specs they were run of the mill 400 ish horse hyd flat sbc's, the stud issue happened to a cpl of guys I raced with, one I saw the night it happened...I would agree that it was the stud because he replaced it with no future issue, my point was that the girdle is not a 100% fail safe against studs breaking.

[cgarb]

I've seen people crash a dirt car and break the starter clean off the motor...is that the starter bolts fault?

[GARY C]

Just thought I would do some digging...
"This was our very first weird test of the series. Most people would never think of installing a stud girdle on such a mild engine, but we're not most people. In last month's tests we witnessed the 3/8-inch screw-in studs in the heads flexing as we lashed the valves. The flexing was visible to the naked eye, so we hypothesized that it might kill some lift and duration. In an attempt to prove our hypothesis correct, we installed a COMP Cams stud girdle, which ties all the rocker arm studs together adding tremendous rigidity. It didn't help. Power and torque actually fell off at most rpm. We can't explain why, but the results speak for themselves. The stud girdle will come off next month."

CAM..COMP Cams XE256H cam (256/268 adv duration, 212/218 duration @ .050, .447/.454 valve lift, 110 lobe separation.

Scroll down to article section 8!
http://www.superchevy.com/how-to/engine ... art-three/

[kirkwoodken]

I'm asking because I don't know! Could the stiffness induced by the girdle increase a tendency for valve bounce? I can imagine the slight bending of the stud cushioning the valve closing under some conditions.

[Zmechanic]

I'm asking because I don't know! Could the stiffness induced by the girdle increase a tendency for valve bounce? I can imagine the slight bending of the stud cushioning the valve closing under some conditions.

I'd argue that if that was the case, then the valvetrain was wrong. If that theory is correct, then once the true motion of the cam was imparted on the spring and valve, it lost control. So the combo is to blame, not the girdle. It very could be true that the stud "ate" some of the cam acceleration and softened what the valve and spring saw.

Usually an increase in stiffness increases resonance frequency, which is good news in most cases. Usually you want the spring to be the only thing flexing if you can help it. Anything that flexes and also has mass is a tuned resonator, it's just a matter of where the resonance is and how well damped it is. Of course, the final word would have to be a spintron in their case. If the spintron showed no loss of valve control with the addition of the girdle, then perhaps they got lucky with the flex compensating for an improper cam selection..