Copper Head Gasket Bolt Torques

A comment by hobot about over-torqueing Commando head bolts reminded me of this service note. For those who don't already know, the factory recommended increasing the head bolt torques by 5 ft-lbs over the service manual specs when using copper head gaskets. You might also find their comments about gasket sealer interesting. I apologize if this has already been posted. I did search the forum and not find it.



Ken

Does the increase in torque settings apply to 850 engines aswell ? I must admit to always putting a couple of extra pounds on, but not as much as on the service data sheet.
thanks
sam

Ken,
I always thought they were advising increasing the torque when the thick alloy gasket was used or two copper gaskets were stacked to lower the compression.
Jim

comnoz said:

Ken,
I always thought they were advising increasing the torque when the thick alloy gasket was used or two copper gaskets were stacked to lower the compression.
Jim

Click to expand...

I think you are correct, Jim. That does seem to be how they intended the advice. On the other hand, it does make me believe that they aren't worried that torqueing to the higher spec will take the bolts past their elastic limit. That would mean those who routinely add a little extra torque when tightening them aren't really taking a risk.


Ken

That extra torque note states its for the softer Alu 'taboo' gasket or 2 cooper crushers but in practice I just keep torquing down in stages till either stays sealed and torqued or give up to live with leaks or start over with new gasket and bolts. Do note the Note about octane to get away with taboo ally or 2 coopers. We/I now know the nuts treads are made weaker than male thread to protect the more expensive to replace male item but when do we know to toss the long side of our vital fasteners so the torque to clamp force developed don't get so far out even twisting bolt in half would not clamp well. Trixie's male engine fasteners are now on like 6th undoing not counting the ones from Peel strained testing - so should I bite deeper in Commando wallet to get them replaced? How do racers decide, by choice or by failure?

I use 5 + extra lbs on both composite and solid copper for the race bike, just std manual specs for the road bike with a composite gasket. Light spray with copper based adhesive both sides
No blown gaskets to date
I have run my torque wrenches over a torque analyzer so know where the exact settings need to be.
Regards Mike