Retorquing ALUM heads after install

[turbo nasty]

This is for a friend. Fresh built engine for low 10's high 9' and he hasnt retorqued the heads and feels he shouldnt.

Based on teh fact that he has been told by a head manufacturer and his engine builder that the heads dont "normally" have to be retorqued.

GN1 headed car with cometics and ARP studs and gaskets were sprayed (not sure if between the layers though).

There has been coolant leaks evident from streaks down the block and his plugs show contaminants that could possibly from coolant seeping into the CC & the coolant level is dropping some. He has NOT used seal tabs yet

Local car guys, we all say check the head bolts/studs with alum heads.

Just for future search sake and some tech here what yall think?

 

[turboclam]

My experience...

I rebuilt a motor with GN1s and after about 3000 street miles and low boost I finally made time to retorque the heads. I found that the center bolts on both heads were out of specs. I run RJC headgaskets too.

 

[yullose]

I just put a set of TA aluminums on mine with .045 Cometics and ARP studs.

I ground off the rivets and took the layers apart. I put the gaskets on, one layer at a time, making sure to smear RTV silicone around every coolant passage on every layer of gasket, including between the block/gasket and head/gasket.

I first torqued them to 65ft lbs with 30wt oil, then straight to 80ft lbs.

I've run the motor a few times, heat cycling it about a dozen times or more. I even ran the boost up to 27-ish already, just trying to tune on it a little.

Sofar, not a drop of water and zero indication of any kind of leak. I didn't use any cooling system sealants or tablets, but I DO run a very low 7psi radiator cap like those recommended for copper head gaskets.

I fully intend to retorque the heads very soon, just to play it safe.

 

[KevinB]

I never have retorqued my GN1's with copper gaskets and head studs. Never had any problems either.

 

[pdzz]

GN1's with shim gaskets copper coated. Re-torqued twice, after about 5 runs in between. But, I have been told I'm anal... No leaks, or any problems though. Phil.

 

[bison]

All mine moved when retorqued so im sure there is some benefit if you need the extra clamping

 

[galoush]

Retorqued 3 x i did them in smaller Lb increments then speced up to the set # ...... then Retorqued after running............... were on car for 4years W/o leaks etc....... just took them off tonight for rebuild of short block

 

[Alky V6]

There is no downside to retorqueing the heads. Only the time to do it. On the other hand, ...

 

[GNDriven]

Retorque heads. Does this mean a higher torque value should be used or the same?
Also, I am not going to use the same torque wrench originally used. Heard that torque wrench can easily differ 10%. So if the torque wrenche is not calibrated than I could be applying 8 lbs of force over the orginal 80lbs. Is this a problem?

 

[turbo nasty]

GNdriven is said person that this thread is referring to

Retorque heads. Does this mean a higher torque value should be used or the same?
Also, I am not going to use the same torque wrench originally used. Heard that torque wrench can easily differ 10%. So if the torque wrench is not calibrated than I could be applying 8 lbs of force over the orginal 80lbs. Is this a problem?

Back the fastner off approx 1/4 turn and pull it to spec or just tighten from current fastner postion to spec, I prefer first method.

For all you know said torque wrench could be 10% under spec as well. Get a good quality torque wrench with a good track record/customer feedback and use it. The 10% concern isnt going to make or break your application.

Others please chime in

 

[meanmachine]

Maybe the different tourqe wrench is the one that is off 10%.?? just use a name brand. Then back a fastener off a 1/4 turn then retourqe it to spec (one at a time).

 

[GNDriven]

That is what I meant, the two torque wrenches being used (1.engine builders - 2.Bud's wrench) could differ in the measurement by 10%. Only if they were both calibrated would I have some faith they would both pull the same amount.

I have talked with some good engine builders that stated I should not have to re-torque. It is not their common practice. Now in this case, there is some slight evidence of perhaps coolant getting into the chamber. This has not been completely proven yet. I am wanting to do a leak-down test to see if there is bubbling in the radiator. So like most things with this car, retorque is like black and grey!!

 

[turbo nasty]

Just retorque the things...your killing me.

 

[J-B Racing]

TA Heads here and NEVER re-torqued after 2 years..:smile:

 

[jpwalt1987]

Gn1s, cometic gaskets, ARP studs@70ft/lbs-----No retorque and No leaks

 

[Mad_Trbo]

Retorqe or not

I have come to find you don't necessarily need to retorque.

On the note of seepage, when putting together this last engine I had some issues with seeping into the valley. So I finally took the heads off and used a 5/16 stud where the 14 bolt head provides a provision along the top side. These were torqued to somewhere in the neighbor hood of 40ftlbs just to provide additional clamp and my leaking problem stopped.

When looking at the head in relation to the block there simply was little mating surface area which probably led to reduced clamping force. Additionally the amount of distance between that outer stud and the inner stud was considerable. This also promoted in my opinion a problem with clamp. I do believe a large majority of people running the aluminum heads suffer these issues due to the lack of face to face material and the spacing between studs.

We'll see how long this block of mine lives with all these modifications and go from there.

Maybe just maybe one day I can get me one of those TA aluminum deals, just depending on how hot this engine is once it's all said and done.

 

[turbo nasty]

Good info here guys, keep it coming

 

[Nick Micale]

Just my opinion after dealing with a couple hundred engines with new and "used" aluminum heads.

On ALL new builds we do, or highly recommend, a re-torque after a heat cycle. Just pull to the original torque spec. If we find and bolt or stud moves, we do it again after a couple more heat cycles.

Since all new alum heads "season" or, take a set, we recommend re-torque until they no longer move.

Bolts and studs also take a "set" from new to used. I don't ever remember on a fresh build a re-torque when not one bolt or stud did NOT move, usually more than one.

One other thing we have found over 20+ years of replacing head gaskets and building engines. All seems fine with low to moderate boost. Then an owner says all is good there, and pushes mid-20 psi or higher and wonders why all of a sudden, there is a problem?

Don said it best, no downside to doing a re-torque except a little effort, but there is a good possibility of setting yourself up for much grief by not doing it.

 

[Rodney87GN]

Someone above mentioned this, and have read it elsewhere in previous posts...but when doing a retorque, why would you first back off the fastener a little and then retorque it? Doesn't that defeat the purpose of a retorque?

I work on helicopters for a living and any critical component that requires a retorque after so many flight hours gets checked at the same torque that it was installed at... if it moves you check it again after xxx flight hours. And if it moves again you replace the fastener. But NEVER do you back off a bolt/nut!

I agree with Nick...just check the fasteners at the installed torque and call it a day.

 

[yullose]

Just a quick update I felt would be relavent to the discussion...

I retorqued my TA aluminums tonight and found 2 studs loose... Not "super loose", but needing a good 1/2 turn to be good again. Only one stud on each side was loose, and it was in the same location... #2 in the torque sequence on each head... an outside, short stud. Just thought that was odd... and thinking to myself now... "DAYUM I'm glad I retorqued them!!!".

Luckily I was able to get the socket on all of them easily without having to disturb valvetrain or headers. (I also don't have AC on firewall )

Doing the retorque, I DID NOT loosen/retighten the studs. I just set the wrench at 80ft lbs and pulled on each one. Only those two moved (alot)