After about 500 miles on my new 383, the valve noise changed. I parked, pulled the valve covers and I had a broken Stud, luckily it was held in place by my stud girdle. I contacted AFR who built these heads for my application, comp cams street roller, and when I told them that I had used Comp Pro Magnum roller rockers, they said that the studs needed to be longer due to the large trunions on the Pro Magnums. They made no comment to my statement that the studs were not concentric and that my stud girdles pulled the tops into alignment. When I asked why I wasn't told about this (I got a stud upgrade along with valve and spring upgrade for my application) it was stated that they didn't know what type of rocker I was going to use...True. I called Comp Cams and was told that they were not aware of this being a problem with there Pro Magnums. (if I messed up I wish they would tell me so I can get this right).
Now it makes sense to me that if you are using longer valves & pushrods that the studs would have to be custom sized as well. Can any engine Guru's help me out here.

 

I think rocker stud length is one of those commonly overlooked items that comes back and bites you. I almost made the same mistake myself. Recently swapped out a set of comp roller tip rockers for magnum full rollers. The Edelbrock studs that came with the heads worked fine with the roller tip rockers but would have been short with the full rollers. Had to go from a 1.75" stud to a 1.9". If you look at summit you can select studs by length. ARP has pretty much any length you need.

A good test would be to install the polylocks that came with the rockers. The allen key should be nearly flush with the shell of the poly lock if the stud is the right length.

 

Zwede, Thanks, another thing I noticed was the rockers were riding on the treaded portion of the stud and only a small amount was on the shank. You have to have some of the threaded portion in the trunion for lash adjustment, but I would think the magarity should be riding on the shank ??

 

Yes, I went through this with my AFR 195s, I am using a different ARP rocker arm stud with a longer shank, but I do not have the part # off-hand. Also, how do you set your lock nut? If you seat it down on top of the stud and then give the adjusting nut an extra crank to lock it down you will find stud pieces under your valvecovers in short order.

 

With stud girdles you don't use polylocks. But I'm curious, what is the correct way?

 

I've heard of this but I'm suspicious of it. I always set my rollers that way on my Camaro and after 100K miles I had NO broken studs. I'm thinking that breaking studs is a symptom of another problem. Probably not enough thread engagement (stud too short).

The way I set mine is to tighten the allen some and then turn the hex a little to lock it all down. I'll be sure to post back if I break anything!

 

I don't think it matters much. The poly locks are turned down on the bottom and slide into the trunnion stabilizing it.

 

I dont know if this is your problem but what brand studs are on the heads? are they arp?

 

zwede: A little snug to lock them in is OK, I was referring to the "I'll give it a 1/4 turn people." LOL. I had a guy that kept breaking the AFR studs on his 305cc BB heads and was talking about how they were junk, ect ect. I asked him how he tightens them down and he said he sets the poly lock and then turns it a half turn to lock them in...LOL, he was shearing the studs off. Because I use stud girdles I get them as tight as possible with my T-handle allen.

jimmygmartin: ...Every set of stud girdles I have used have poly locks, you should have a set-screw in the nut to snug up the threads for more accurate valve lash in addition to more torsional rigidity with the stud girdle/stud interface.

 

VETDRMS : Mine are Moroso single bar girdles, U-bolts w/special dedicated caps with no polylocks. I don't think the studs are ARP, as they are not concentric (out of line due to wobble) and I believe that this is the true sorce of the problem. I'm upset with AFR right now since the heads were built for my application, I paid for options including a rocker stud upgrade, blaming the problem on comp cams is just passing the buck. I'm not really looking for any refunds just honest answers and guidance.

 

Do the studs have a dimple on the top of stud or are they flat or say ARP on top of stud

 

They have a dimple on top and do not say ARP.

 

Stud misalignment could be due to poorly machined studs (concentricity-parallelism) ... or ... heads' poorly machined stud pads (all pads in same plane) / poorly threaded stud holes (parallelism).

 

I know that alot of studs have this problem, and ARP asserts that theirs are good. I also relize that this could be a result of poor machining, but I hope this is not the case, if it is then I am going to have some words with AFR.

 

Then throw them in the trash ,those are the cheap ones,
I've already learned my lesson on cheap rocker studs,on more than one engine
they just keep breakin one at a time,so do it right and change them out,with ARP and if you want to make sure they don't break agian go with 7/16" stud.

 

Good advice, just one thing, they are 7/16" studs.