Head Re-torque Process

I replaced the stock cylinder studs/nuts with an APE set a couple years ago. I've installed a different head a few months ago, and checked the cylinder head nut torque a couple times since. They seem fine, but I'm wondering if my method is correct. The nuts were oiled, and initially torqued to 42ft. lbs. They were rechecked at the same torque setting.

Can someone briefly explain the proper re-torque method? Does each nut need to be broke loose prior to re-torquing?

Simply retorque after a full cool down cycle. No need to loosen and then retorque, just retorque.

I've built hundreds of kz's and all I do is torque the head, run it up till hot and then leave overnight to cool and re-torque the next day.
Some people like to slacken them off and re-torque but it's a waste of time.
I usually re-check them after 500 miles or so with the engine cold and that's it until the next time the head is off.

That would suggest things have not changed. May I want to re-torque to a higher setting, say 45ft/lbs. next time, or just leave it alone?

Leave it as is.

zed1015 wrote: Some people like to slacken them off and re-torque but it's a waste of time.

Proper torque depends on the fastener being in motion when the wrench goes "click". If you're not going to re-torque, fine. But if you DO re-torque, the fastener needs to be loosened a little first, then re-torqued.

The force required to get two surfaces to start moving against each other is higher than it is to keep them moving. It's dynamic friction vs static friction.

If you just put the wrench on there, and push, if one bolt moves (but not all of them), now your head bolts are not all at the same torque.

bemoore
The last time I went through them, one nut turned (broke loose). It rotated at least an additional half-turn before the applied torque clicked the wrench. The rest didn't turn, so is that one nut now tighter than the others? I assumed they were equal...hence my question.

That is why it is good to back off a 1/4-1/2 a turn and re-torque. If there is any corrosion between the washer/nut and head, the torquing of the nut is sometimes not sufficient to break the corrosion or other resistance between the fasteners. It may feel tight, but because of resistance, the fastener may not be properly torqued.

daveo wrote: bemoore
The last time I went through them, one nut turned (broke loose). It rotated at least an additional half-turn before the applied torque clicked the wrench. The rest didn't turn, so is that one nut now tighter than the others? I assumed they were equal...hence my question.

Yes, that one nut is tighter than the others. I would re-torque them all again as follows:
- Loosen one nut 1/8 turn or so.
- Re-torque THAT nut to spec, making sure that the nut is moving when the wrench goes "click".
- Repeat for the other nuts

You don't want to loosen more than one nut at a time.

I'm uncertain about the torque spec, since these are not stock studs and nuts. They easily took the 42lbs/ft. initially,
and I'm thinking of going to 45 with them, just to add a wee- squeeze.

Daveo, good question. I have often found the nuts never move when re-tightening and once loosened [backed-off] will move a further 1/4 to 1/8 of a turn. Bemore has a good theory that.... the nut should be moving when the wrench goes "click".

RegardZ

daveo wrote: I'm uncertain about the torque spec, since these are not stock studs and nuts. They easily took the 42lbs/ft. initially,
and I'm thinking of going to 45 with them, just to add a wee- squeeze.

42 ft lbs is plenty do not push your luck you can pull threads out of upper case as for retorque loosen 1 nut at a time and tighten to 42ft lbs repeat for other remaining head nuts also no more than a 100 in lbs on 2 outer 6mm bolts do all this with engine cold.