Torque torque............

[mark030358]

Gents,
Just done 1000 miles should I re torque my head? Do I undo 1/4 turn then re torque?

cheers
Mark

[type26owner]

Hey Mark,
Why did you wait so long? Almost universally the head gasket vendors say to retorque after the engine it has come up to temperature and then cooled off completely the first time. What brand/type of headgasket is it?

I have the official Powerpoint document on the headgasket from Payen. If you want it, here is the link. http://briefcase.yahoo.com/[email protected]

I don't know what to advice you to do now other then tell you to call their engineering department for help. I found them by calling Federal-Mogul first and found out Payen was their European subsidary. They were very nice and had no problem with me calling to chat.

[rgh0]

Mark

Rather than back off the head bolts and then retighten I normally tighten the bolts until they move slightly tighter and break any bond between the bolt and head threads and then check the torque. Normally a slight jerk on the wrench will move the bolt a fraction of a turn ( maybe 5 or `10 degrees) if just bring it up to the right torque with the torque wrench does not cause any movement.

The head gasket does not recover if it looses compression so I dont like slackening off a head bolt ever until I intend removing the head.

Remember to make sure your torque wrench is calibrated. A racing friend of mine struggled with blowing head gskets for a couple of years unitl he discovered his toque wrench was reading about 30% low.

Rohan

[type26owner]

The head gasket does not recover if it looses compression so I dont like slackening off a head bolt ever until I intend removing the head.

Spot on. If you look into the technical documents for this stuff you'll find a lubricated bolt only transmits about 15% of the force into stretching the shank, the rest is wasted as friction under the head and on the threads. A unlubricated bolt yields about 10% or less. Which do you have now? For this reason I believe a torque wrench is rendered useless. The idea is to stretch the bolt and store clamping energy. Just pull on them if you must until they move and stop at the same angle value that Rohan suggests. Personally, if the engine is not consuming any coolant I'd leave it alone.

Payen is in the UK. Did ya see the Payen copper/aluminum gasket that came out of my twinkcam? I didn't have a clue it was like that. The engine was taken apart for a different reason all together. That was the last time I installed one of those gaskets!

[mark030358]

Gents,
Interesting comments. If you look at the origional lotus service manual that comes with the car it says to check head bolt torques on every service??? Very strange.

I know in the past on my old TR's I would re torue after 1000 miles running.

any more thoughts?

cheers
Mark

[type26owner]

The science of torquing fasteners has changed in the intervening years though and so has the headgaskets. Suggest you change over to a composite headgasket that does not require retorquing next time. FelPro makes one that all the racers use.

Looked for the composite headgaskets up in the DBE catalog and there's no info on them to my surprise.