Retorqueing Composite Headgaskets.

[dfarr67]

I know this is a subject beat to death.

We caught an engine that had poor assembly and the head was torqued to 25ft-lbs (I suppose the guy walked away from the job and didn't mark the studs completed- I found a lot of loose fasteners on this engine), ARP studs call for 90ft-lbs. Toyota 22R low boost turbo at 8lbs, these engines never had a stellar head gasket track record saying that the same gasket is the same part number for the NA engine and their turbo charged version. OEM gasket that says it doesn't need a retorque, and the mechanic I was dealing with stated the way HE initially torques it down does away with retorque (I don't understand this statement). So I doubt the factory saw these trucks back for a retorque nor would I imagine most shops see their customers back. I think after a few cycles a retorque would re-equalize the loading across all the studs? I would need to borrow a high end torque wrench which I hate doing- but wth for the every few years I need to do it. What is the experience out there- leave it or make the effort.

[Walter R. Malik]

I know this is a subject beat to death.

We caught an engine that had poor assembly and the head was torqued to 25ft-lbs (I suppose the guy walked away from the job and didn't mark the studs completed- I found a lot of loose fasteners on this engine), ARP studs call for 90ft-lbs. Toyota 22R low boost turbo at 8lbs, these engines never had a stellar head gasket track record saying that the same gasket is the same part number for the NA engine and their turbo charged version. OEM gasket that says it doesn't need a retorque, and the mechanic I was dealing with stated the way HE initially torques it down does away with retorque (I don't understand this statement). So I doubt the factory saw these trucks back for a retorque nor would I imagine most shops don't see their customers back. I think after a few cycles a retorque would re-equalize the loading across all the studs? I would need to borrow a high end torque wrench which I hate doing- but wth for the every few years I need to do it. What is the experience out there- leave it or make the effort.

Most companies will tel you that there is no need but, I re-torque them anyway.

[rebelrouser]

The gaskets do not need to be retorqued after running. But if you go over them several times on during the original installation you sometimes find the head and gasket settles a little and you will find some a little bit loose. Rember just because something is made of metal doesn't mean it does not give and flex a little. So at least what I do is keep going over the bolts until the torque wrench clicks as soon as I pull on it. And especially on aluminum heads you will most of the time see an impression of the fire ring in the gasket in the head, the aluminum has to compress to do this.

[BillK]

Years ago I was talking to somebody at Fel Pro and they told me to use this procedure on high performance and race engines:

1. Torque the head however you normally would. In your case 90 lb ft with the ARP studs and make sure to use their lube. It makes a huge difference.

2. Walk away for a few hours or overnight if you have the time.

3. Starting with the first bolt in the sequence, loosen it about 1/2 turn and then immediately re-torque it to the final spec. In your case 90. Go through the entire sequence one at a time and do the same thing.

The theory behind loosening it first and then re-torquing it is that the friction on the nut might keep it from turning if you just try to re-torque it. Same reason that a lot of times head bolts (or any bolt) will sort of snap loose when you remove them.

I have been using that method on any performance type build.

[dfarr67]

Ten bolts I think- easy to access as well.

[In-Tech]

All good strategies above. At least a couple heat cycles too are necessary for endurance race stuff.

[Tom68]

When we retorque, do we back off a bit first so it's a smooth run to final torque.
i.e. you aren't just clicking the torque wrench because of breakaway torque ??

[In-Tech]

correct

[dfarr67]

It's being tuned on a chassis dyno, so if they don't push the gasket it will be good to go for retorque.

[BOOT]

The gaskets do not need to be retorqued after running. But if you go over them several times on during the original installation you sometimes find the head and gasket settles a little and you will find some a little bit loose. Rember just because something is made of metal doesn't mean it does not give and flex a little. So at least what I do is keep going over the bolts until the torque wrench clicks as soon as I pull on it. And especially on aluminum heads you will most of the time see an impression of the fire ring in the gasket in the head, the aluminum has to compress to do this.

One of the reasons I like iron heads. Also why I think it's a good idea to use a non hardening thread sealer for head bolts on alum heads.

[David Redszus]

Gasket manufcturers know the degree of compression their products under go as a function of torque.
They are in the best position to advise regarding re-torque or not.

What is not often considered is that fasteners are subject to relaxation and reduction of clamping force.
And, they are subject to stress forces due to combustion pulses.

[dfarr67]

Little off point- for a guy that doesn't make his living off of professional tools- what is a good value you have noticed for 1/2 torque wrench, I bough a KD for lug nuts and I know it's off by 10ft-lbs. I'm guessing just buy a used SO or MAC and take it to the local dealer for calibration??

[fordified]

Little off point- for a guy that doesn't make his living off of professional tools- what is a good value you have noticed for 1/2 torque wrench, I bough a KD for lug nuts and I know it's off by 10ft-lbs. I'm guessing just buy a used SO or MAC and take it to the local dealer for calibration??

Precision Instruments

[digger]

composite gasket with stud torqued sub yield always retorque

[Schurkey]

Little off point- for a guy that doesn't make his living off of professional tools- what is a good value you have noticed for 1/2 torque wrench, I bough a KD for lug nuts and I know it's off by 10ft-lbs. I'm guessing just buy a used SO or MAC and take it to the local dealer for calibration??

Precision Instruments

I bought a used torque wrench, (Snap-On) and then had it checked. No parts available, didn't meet calibration specs. Torque wrench was scrapmetal.

Go on Amazon, look at Precision Instruments and CDI.

Keep in mind:
1. Team Torque and Angle Engineering charge DOUBLE to test/calibrate electronic torque wrenches compared to "clickers".
2. "Split Beam" torque wrenches generally cannot torque in the reverse direction, and usually don't have a ratchet head that can be reversed. But at least you don't have to reset the torque adjustment to the bottom of the scale after use.
3. "Deflecting Beam" torque wrenches have fabulous inherent accuracy and cheap pricing. The inherent accuracy goes away because of the user-error they promote. Unless you're testing torque--like determining bearing preload on a differential assembly--"Deflecting beam" torque wrenches are for the birds.