Need to know the torque for 3/8" screw in rocker studs. Thx..

 

If these are real rocker studs with properly prepped heads and all that, then the part you're actually torquing isn't 3/8", it's 7/16"; and therfore they should be at around 60 ft-lbs.

 

ARP screw in 3/8 studs are torqued to 55 ftlbs. Don't forget the thread locker.

Eric

 

Do not use thread locker.

If these are stock heads, the studs go into the water jacket. If they are aftermarket, they could go into the water jacket, or they may go into the intake ports themselves. In either case, they need some type of non-hardening thread sealer; such as Loctite PST, or Permatex 300. You will surely have leaks in very bad places, either coolant into the oil or oil into the intake, if you use something besides thread sealer.

 

Are these going into cast iron or cast aluminum heads?

 

whoops, meant sealer, not locker

Eric

 

HEY! I think 35+ lbs. are too much for ALUMINUM heads.

I did a search in this forum and I used 35 lbs. for alum. 2.8l V6 heads.

Please, review again.

Regards,

Denis V.

 

Torque is a function of hardware size, not casting material.

60 ft-lbs (or 55 for that matter) is not at all excessive for aluminum. Transmission bolts for example are routinely tightened to that level.

Personally I Heli-coil all threads in aluminum heads, so the fact that they happen to be aluminum is totally irrelevant. But even it the threads go directly into aluminum, if the hardware didn't need to be that tight, they would have made it smaller. If they're too loose, the normal loosening action of being attached to a moving part, will tend to back them out over time and temperature cycles.

Of course, I haven't built very many SBCs or anything, with any of them having aluminum heads or cast-iron ones either, so I wouldn't know what I'm talking about.

 

RB is correct. The part that threads into the head is 7/16".
The heads are 083's that have been professionally prepped.

I bought a tube of Permatex 14A Thread Sealant w/Teflon (item #80631).
It says that "adjustemnts can be made up to 24 hrs after application without damage to the seal". Not sure if that qualifies as "non-hardening" or not.

 

It all depends upon the alloy and heat treatment/finishing of the materials. ASTM has a different view of ultimate torque in white metals. Any of you career metallurgists out there want to pipe in on this one? Taking a 7/8-14 to 800 lb/ft in almost any white metal is nearly a guaranty of problems with the threads.

I was only asking becasue some of the aftermarket "billet" heads have some significant question marks about material quality and treatment.

 

AFR recommends 60 ft/lbs in their aluminum heads. I've always used 60 on heads when in doubt without problems.

MOST SBC heads the intake studs open on the bottom into the roof of the intake port and so, require some sort of sealant that can live in a gasoline environment to prevent a potential vacuum leak (and oil consumption, obviously).

MOST SBC heads the exhaust stud is a blind hole going nowhere and so requries no sealant of any kind.

 

I think it might have been RB that once remarked "Arguing on the internet is like competing in the Special Olympics. Even if you win, you're still retarded." If I attributed that quote to the wrong person, I apologize. The point is that I don't intend to argue, but I'll agree with each of you in some instances. The Vortec, LT1, and soem other factory heads have rocker studs that either terminate in the intake runner or a blind hole. Stock 416, 882, 441, and 993 heads (and probably other stock castings) have rocker stud holes that enter the cooling jackets over the chamber crowns. In either case, sealant to prevent coolant or intake leaks is a good idea. 60 ft/lb is probably fine for a 7/16-14 thread in either material, but just be sure the torque wrench is calibrated or you may have issues with aluminum cold flow and fastener failure.

 

Geez I love this furom.Thanks for the info guys!