This doesn't affect very many here but I thought I would post it anyway.
I have been running a stud girdle on my motors for the last 20 years. I thought it was a good idea at the time but now I wonder.
I run 200 pound springs on the seat and 550 pounds open.
I spent the weekend setting the valve, I am running out of work, the 540 is just about ready to fire. The car other then plugs and timing is done.
I set the valves very carefully, recheck 2 more times and then install the stud girdle. I then recheck very valve 2 more times and found a number the clearances very carefully set before are suddenly way off. It can tighten , and I found they tightened rather then loosened. They tightened up to .010.
I spent an entire day reworking on stud support at a time. Using feeler gages and eyeballing I would modify one support, reinstall, check clearance with the girdle tightened down and move on to the next.
Is a girdle really necessary? If not custom fit do they do more harm then good? I don't know but it is done now and with everything snugged up the clearances set before remain the same after installing the girdle.
This is an old old shot. Not my new 540

 

I don't want to sound like an idiot, but what the hell, ain't the first time. What is that thing supposed to do?

 

It stabalizes the valve train. Your rocker arm pivots on a stud. Think of 550 pounds rocking at the end of a stud, a 7/16 stud. YOu can get deflection of the end of the stud so your valve train starts to flex.
The stud girdle slides over the ends of the stud creating a strong support. You no longer have a free standing stud. It is screwed into the head at one end and has a precision fit support on the other.
It just stablizes the valve train.

 

Ahh, ok. Thanks
So why is it throwing off your valve clearences? Something in the machining off? Are the Intake and exhaust clamp parts matched to the center bar like rod caps?
now that I am expert I can troubleshoot, LOL

 

I use stud girdles religously!
first off with the spring pressure your using I hope you have 7/16 studs and not 3/8 studs cuz they will flex bigtime with the pressure.
also if the alignment of the studs is tweaked everytime you tighten the girdle itll make the tolerances out of spec.
I would guess your studs are slightly bent and need replacing.
I also didnt see any mention of pushrod guides installed either.

 

Norval I usually get the lash close, then tighten the stud girdle and recheck. I find that the stud girdle pretty much re-aligns the studs from they're deflected locations as it should. It then strengthens the entire row of stud as one unit. I also always assemble the girdles so that the screws are on the top side to keep the screws from being able to fall out incase a screw ever works its way loose (which I haven't seen), just a **** thing for my sbc, not sure if thats possible with the BBC girdles.

Here's a picture of the girdle tightening screws positioned down, I flipped them so thet are on the top side

 

Norval, I spent an enormous amount of time setting up the AFR stud girdles on my 540's AFR 335cc CNC heads. There is exactly ONE HEIGHT above the valve cover surface where the girdle can fit and not cause stud deflection. This is of course due to the tilted stud configuration on our BBC's. I made up a set of stud girdle locating blocks for mine, to position them at just that perfect height. So that now, it is just a quick drop on deal. It sounds like you got them modified to where the fit well now. So just make up a set of locating blocks for your setup, and you won't even have to give it a second thought again.

 

The heads are new from Brodex so I assume they know what they are doing.Why would my studs be bent? These heads have not been abused and I thought Brodex put out a quality product.

 

I feel I have worked it out where I can pull the girdle, set the valves, reinstall the girdle and no lash changes due to deflecting a stud.
It's all about attention to detail. Take nothing for granted, trust nothing and prove everything to yourself. If your gut feeling is something is not right, track it down.

 

As was mentioned ...stud angles are often the cuplrit...many times they aren't drilled straight...and the longer the stud..the worse it gets. The Brodix I've dealt with are usually pretty straight though.

I use an old ancient Moroso single bar with u-bolts. My procedure is to roughly get all valves set to *0* lash. Then I install the girdle and tighten all the u-bolts up snug. THEN I roll motor over and set the valves. This way the other 7 are holding everything in place as you set each one. It is very repeatable and if you go back over them, they are where I set them.

The times I've used the .600/.620 lift flat tappet in mine, I went ahead and left the girdle on..figured it couldn't hurt anything.

FWIW- the studs on mine are modified 351 Cleveland ones. Once I had pushrod length where it needed to be and geometry correct, I didn't like where the rocker was riding on the shank area and there wasn't enough thread engagement for the nut even with the long ones they make. I found some ARP's made for the old SVO Clevelands where the studs actually extended up through the valve cover and the valve cover was the girdle. I shortened them .300" and they have been perfect!

One my single bar one, with all the u-bolts loose..you can *feel* where it fits right. You slip it up and down and you can see the nuts lining up in the bar. I agree...if you get it out of whack..you can really deflect things if you tighten it down in the wrong position or if studs are funky.

Some day I'll cheek up for a shaft system....just 'cause they are pretty!!


JIM