Aftermarket heads: Rocker stud holes - Chevelle Tech
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post #1 of 12 (permalink) Old Mar 29th, 20, 5:16 AM Thread Starter
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Aftermarket heads: Rocker stud holes

Since I've had a bad experience with header bolt holes breaking into the water jackets on aftermarket aluminum heads in the past, I have to pose this question. A number of years ago I remember someone on this board posting a thread about going crazy for several weeks trying to get his engine to run right with a new pair of fully assembled AFR aluminum heads he purchased. When he finally called AFR, he was told that some of the rocker arm stud holes on their cylinder heads break into the intake ports, and that it can cause vacuum leaks. He was instructed by AFR to remove all of the rocker studs that they installed, and re-install and torque them down with thread sealant to stop any vacuum leaks. And once he did that, the problem was solved.

That was a number of years ago, and I don't even remember who on here that was, but can this still occur with AFR or with any other aftermarket cylinder heads? I'm thinking that if it can, then the thing to do with any heads purchased fully assembled, would be to remove and re-torque the studs with either thread sealant or Red Lock-Tite 271 as a routine measure. Has anyone here ever seen any of the threaded rocker stud holes break into the intake ports on aftermarket heads from any manufacture? I didn't have that problem with the AFR heads that I bought a number of years ago, but I just thought I'd ask.

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post #2 of 12 (permalink) Old Mar 29th, 20, 8:26 AM
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Re: Aftermarket heads: Rocker stud holes

From the AFR BBC head installation sheet:

Quote:
ROCKER STUDS:

"AFR BB Chevy heads require two different length
rocker studs. The (8) shorter studs (referring to the coarse thread
length that screws into the head) must be installed on the intake side
with a small amount of teflon or some other non-hardening thread
sealer. Without thread sealer oil is drawn into the intake port under
vacuum and will cause excessive smoking. Conventional bolt thread
lubricant can be used on the longer (8) exhaust studs. Never use a
shorter stud on the exhaust side.
NOTE: Torque Rocker Studs to 55 Ė 60 ft./lbs."
I would guess that anyone having a problem drawing oil past the intake rocker stud threads did not follow the installation instructions or maybe AFR didn't!

Dave
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post #3 of 12 (permalink) Old Mar 29th, 20, 9:42 AM
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Thumbs up Re: Aftermarket heads: Rocker stud holes

I just put a new top end on my 406 this winter and went with Dart iron eagle platinum 200's. the engine builder that I had check my heads and drill my steam holes was nice enough to show me that the rocker stud hole went through into the intake runner. I'm glad he did, since this is the first set of aftermarket heads I've ever had. He recommended Right stuff on the threads.
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post #4 of 12 (permalink) Old Mar 29th, 20, 9:47 AM
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rick
 
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Re: Aftermarket heads: Rocker stud holes

My Brodix 294 RR-R int. studs go into the runner also, I used ARP 235-7205 rocker studs and cut the exh. studs to proper length then used Permatex high performance thread sealer on all the studs, Brodix inst. and tech support said to use red Loctite but I went with Wolfplace & BillK and I think a few others info, I also used my finger tip to wipe any sealant that got into the runner before it dried, hope that helped to answer your question
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post #5 of 12 (permalink) Old Mar 29th, 20, 9:57 AM
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Re: Aftermarket heads: Rocker stud holes

Quote:
Originally Posted by shovelrick View Post
My Brodix 294 RR-R int. studs go into the runner also, I used ARP 235-7205 rocker studs and cut the exh. studs to proper length then used Permatex high performance thread sealer on all the studs, Brodix inst. and tech support said to use red Loctite but I went with Wolfplace & BillK and I think a few others info, I also used my finger tip to wipe any sealant that got into the runner before it dried, hope that helped to answer your question
Same here permatex teflon thread sealer.
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post #6 of 12 (permalink) Old Mar 29th, 20, 11:05 AM
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Re: Aftermarket heads: Rocker stud holes

I use the red Loctite on the rocker studs.
Use the Permatex #1 on intake bolts.

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post #7 of 12 (permalink) Old Mar 29th, 20, 2:35 PM
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Re: Aftermarket heads: Rocker stud holes

Quote:
Originally Posted by David Bates View Post
From the AFR BBC head installation sheet:



I would guess that anyone having a problem drawing oil past the intake rocker stud threads did not follow the installation instructions or maybe AFR didn't!
This ^

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post #8 of 12 (permalink) Old Mar 29th, 20, 2:37 PM
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Re: Aftermarket heads: Rocker stud holes

Quote:
Originally Posted by BillyGman View Post
Since I've had a bad experience with header bolt holes breaking into the water jackets on aftermarket aluminum heads in the past, I have to pose this question. A number of years ago I remember someone on this board posting a thread about going crazy for several weeks trying to get his engine to run right with a new pair of fully assembled AFR aluminum heads he purchased. When he finally called AFR, he was told that some of the rocker arm stud holes on their cylinder heads break into the intake ports, and that it can cause vacuum leaks. He was instructed by AFR to remove all of the rocker studs that they installed, and re-install and torque them down with thread sealant to stop any vacuum leaks. And once he did that, the problem was solved.

That was a number of years ago, and I don't even remember who on here that was, but can this still occur with AFR or with any other aftermarket cylinder heads? I'm thinking that if it can, then the thing to do with any heads purchased fully assembled, would be to remove and re-torque the studs with either thread sealant or Red Lock-Tite 271 as a routine measure. Has anyone here ever seen any of the threaded rocker stud holes break into the intake ports on aftermarket heads from any manufacture? I didn't have that problem with the AFR heads that I bought a number of years ago, but I just thought I'd ask.

To be clear almost every rectangle port aftermarket aluminum head out there along with many SB heads has the rocker stud going into the intake port & the larger the port the more the issue.
It is just a matter of the stud & port wanting to share the same space....... usually the port wins

Mike (Wolfplace)
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post #9 of 12 (permalink) Old Mar 29th, 20, 9:09 PM Thread Starter
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Re: Aftermarket heads: Rocker stud holes

I'm glad that I asked you guys about this. Thanks very much for everyone's replies. That was exactly what I needed.
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post #10 of 12 (permalink) Old Mar 30th, 20, 10:54 PM
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Re: Aftermarket heads: Rocker stud holes

Wolfie rides again!

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post #11 of 12 (permalink) Old Mar 31st, 20, 6:31 AM Thread Starter
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Re: Aftermarket heads: Rocker stud holes

Quote:
Originally Posted by Tom Mobley View Post
Wolfie rides again!
Yes, it's good to see Mr. Lewis posting again every once in awhile. Just like some other pro engine builders on here, Mike is a wealth of helpful information for us amatuer mechanics. Guys like these help to keep this classis car hobby and drag race craze alive, and not only due to the great engines they build and sell either.

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post #12 of 12 (permalink) Old Apr 4th, 20, 4:40 AM
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Re: Aftermarket heads: Rocker stud holes

IMO, there are very few like Wolfie that have the successful career in racing engines combined with the willingness and ability to share out. His background is seemingly limitless. Talk is cheap but Wolfie layeth the smack down.

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