Head re-torque question?

y-hate

Gone In Sixty
Joined
May 30, 2001
I`m going to put my M&A heads back on 2morrow need some info on heads retorque...do i re-torque them after the engine is warm after start-up or when it cools down? Do i loosen the head bolts then re-torque them or do i just re-torque them at 85 psi? I`m going to torque my aluimuim heads at 85psi is that the correct? Thanks for any help
 
The problem with retorquing the head bolts/studs in the car, is that you can't get on all of the bolts without a U-joint on at least a couple. Most guys do the torque-down over a couple of days, in slow steps, then back off 1/8-1/4 turn, and re-torque to 85...before installing the engine.

You didn't mention which gaskets you're using, but most of them don't require a re-torque anyway...
 
You didn't mention which gaskets you're using, but most of them don't require a re-torque anyway... [/B][/QUOTE]
I agree with Quickwrench. If you bring the bolts to their final torque spec then back each one off 30-45 degrees and retorque three times before moving on to the next one (in sequence of course), i.e., mate the threads, you'll be okay. Indexing showed an average of 22* increased rotation on each bolt due to thread mating (more than if 100# of initial torque were applied). I don't believe the ARPs stretch much, i.e., l believe "lifting" is caused more by lack of thread mating than by bolt stretch. Drain the block prior to installation, tap clean each bolt hole, torque bolts prior to adding water, install the intake with an old gasket and torque to around 20# after initial torque of around 10# on both heads (to assure proper alignment), increase torque only 10# each increment and do both sides simultaneously, let sit overnight, backoff/retorque in sequence, then FORGET about them. In fact, backing off and retorquing after heat cycles will result in LESS bolt stretch/rotation, inferior thread mating and possibly inferior thread seal. This can be proven by indexing the bolt heads (marking a straight line across them and on the head to visualize change in rotation) prior to the retorque. Good luck, Joel
 
85 with 30W oil or moly? 85 with moly would be high IMO. Just some facts to munch on because I'm not the guru on this but I do have some experience.

Using stock head gaskets and iron heads, I have verified that re-torquing after 3 heat cycles WILL net more compression of the head gasket and in theory help to reduce high boost lift failure.

But if I were SURE I was going to re-torque following a few heat cycles, I would not back off the torque any. I would stop 5 lb-ft before the final torque I was looking for (say 80 in your case), go through the heat cycles, and then go on up to 85. If you back off you will potentially break the seal on your studs/bolts and could actually produce a failure point.

Anyone out there using any sealer they feel comfy would handle movement of the threads and still seal? I sure would like to know because backing off will definitely move them. :confused:
 
I just removed an engine with M & A heads. (Blown head gasket...lol). These were the 1007 gaskets btw.

Originally I assembled it and torqued 'em down to 85 using ARP lube. I also did what someone else suggested and loosened 'em off over a few days and retorqued them about 5 times.

I have always retorqued after a heat cycle but knowing the M & A's are thicker I didn't think I'd be able to in car. And that's correct. At least on the pass side with the air still in.

I don't blame the gasket for it's failure; I was stupid as usual.

Anyway, once I removed the engine I checked the torque on the head with the still intact gasket and it was about 80. I redid it to 85.

The other head is now back on and I'll retorque it after a few heat cycles just because I believe it's better. And it's the driver's side so I'll be able to.

Since we're on the subject I've often wondered why we don't torque 'em higher to start with then allow the heat cycle to "settle" the torque where it should be. Make sense??
 
Top