Retorque head studs after fixing leaks?
 

Some of you may have seen my questions / problems that were posted over on ICDEDPPL's thread on the "Boating on a Budget" forum about his dyno results. Never intended to run off on a tangent, but the gist of it was that I was pressure checking my block with head studs to check for leaks, and had several studs leaking air up through the threads. I pulled the head and fixed the leaks, and torqued the studs to the recommended numbers. My question is whether or not I need to back the nuts off 1/4 turn and then retorque each nut to the recommended setting. I did this the first time because I have seen it recommended to let it sit for a few hours and then follow this procedure.

Engine is a Gen VI 454 block with AFR aluminum heads and ARP studs.

If anything you wanna retorque after a heat cycle.. seems like a waste to do it after a few hours just sitting.

I have found it to be pretty tough to retorque after a heat cycle, especially since some of the head bolts are not accessible without removing rocker arms, headers, etc. I recall that retorquing some time after heads are installed allows for the gaskets and studs to "take a set" or something along those lines.

Couldn't hurt,

Either way u will b fine. I've done them every which way never had an issue. Ive even been in a pinch with no torque wrench and made the bolts tight by feel that was 4 years ago and the boat is on the water every weekend...

I would torque them, let sit few mins, back off 1/4 turn and re-torque, that what we do on out turbo LSX drag radial car running 25+psi boost

The only thing retorquing them will do is burnish the threads for a clean full clamping force of the torque. I've done this several times on diesels. Retorque hot, cold after several miles etc. if you torque them down, back them off and torque again, do that process 3 times, you can go over them a year later and your torque wrench will not move at all. Done it more than once on diesel head studs that require 180 ft lbs.
Btw, that whole process is completely unnecessary on a n/a 700hp or less engine. Not enough cylinder pressure to over come the clamping force of studs in a bbc torqued in sequence.

I talked to ARP when I installed my head studs and they said to seat the threads by torqueing and loosing a few times before final assy.Also you did put the studs in only finger tight ?

What head gaskets are you using? Did you use ARP assembly lube on the threads and washers under the nuts?

Do you still torque them 3 times when the spec is 330 ft. Lbs? Cause ill tell you what after one pass using a 5 ft pipe I'm about ready to fall out and I'll be damned if I'm gonna attempt a 2nd pass.

lol nah I'm good maybe twice, or use extra lube and hope for the best at that point!

Do it the Canadian way. Tighten it until it breaks, then back off a quarter turn.

Yes, I did use the ARP lube on the threads and under the bolt heads and washers. Seems like I recall reading that you don't have to do the thread burnishing if you use their lube, but my brain is turning to mush from all of this. They are Cometic MLS gaskets.

Yes, basically finger tight. Did not put a wrench on them and crank on them. I have seen a few recommendations to run the studs down finger tight and then back off a quarter turn, but that seems to make them feel a little loose to me - makes me doubt the threads will seal very well.

All this torqueing and loosening (beside sounding like a Miley Cyrus concert) don't sound like it would be good for the head gasket.

BudmanII,,the torque and back off 1/4 is for new studs..if they are used then just torque them in inctoments.until you reach the required torque and i go over the bolts several times until they all read the same..then let it sit for a few hours and go over them again..

Great that you used Cometic gaskets and ARP lube. With that in mind, I dont retorque. Get it right the first time, go over it a few times, torque in the correct sequence and move on to something else.