Re - torqueing heads

[Alan L]

Is it necessary to re torque the heads after a rebuild.
Many engines have this recommended after a 1000km or so, after the head has settled.
There is no mention of this that I can recall in Waynes book.
Is it necessary, or recommended?
Thanks
Alan

[304065]

Alan, I understand your question. When I rebuilt the head on my BMW 2002, I had to re-torque it after 500 miles.

For Porsche heads it is neither necessary nor recommended.

[304065]

Re torque your head studs after 1000 km ?

[Alan L]

Many thanks John.
One of my cylinders has a slight weep at the base gasket - after a rebuild about a year ago.
I never re torqued the heads and was wondering why this would occur now , after being oil tight initially. I put some gunk on the base copper gasket as per Waynes book. All the other cylinders are fine, and there are no broken studs - I replaced them.
I can't think what else would cause it other than lack of torque on the head studs.
Alan

[Eagledriver]

I have had the nuts on the headstuds come loose on one bank of my engine before. I think that because of the goop I use on the base gaskets that the headstuds became under torqued when the goop oozed out. I retorqued the nuts and haven't had furthur problems. I would say that normally it doesn't need to be done but there is no harm in doing it and it might help your leak.

-Andy

[Alan L]

Many thanks - will do.
Alan

[carrera30]

This type od dialogue is very helpful for someone like myself that is trying to get the courage to start my rebuild, winter is comming, that's when.

[V12man]

For what it's worth, Wayne does mention this..

In my copy of Wayne's book on page 196 he says and I quote "...and retighten your head stud nuts..." ..."engines with aluminium crankcases typically don't require any additional tightening, but you will probably find that the magnesium case head stud nuts will require at least a quarter turn before tightening up to their final torque."

In the paragraph he states this should be done twice - at 500 miles and at 1000 miles, together with changing the oil and doing a valve adjustment.

[Alan L]

Originally Posted by carrera30

This type od dialogue is very helpful for someone like myself that is trying to get the courage to start my rebuild, winter is comming, that's when.

Carerra 30 - with the help of Waynes book, and this forum, anything is possible. I tackled a complete rebuild from the crank up, as have others. I had some previous experience, but not on the weird and wonderful 911.
My winter project took about 3 months - do not rush it. Allow plenty of time. Taking care at each step pays off - attention to detail. If in doubt - do not proceed past that point. At any point you are in doubt or get stuck - use this forum and you will be away in no time.
Alan

[J P Stein]

I'm in the process of tearing down my 7 year old rebuild....a 2.7L with 9.&:1 Shasta pistons....just got it out of the car. After reading this thread I went out & spot checked my head nuts torque never having touched them since the build.
27-29 ft/lbs near as I can figure(Dilavar studs).

[Alan L]

They will probably tend to freeze on over time - so you can expect erroneously high values of torque if the nuts have been in place for a while - Waynes book suggests 23 ft/lb.
Mine were slack by 3-4 ft/lb.
Alan

[J P Stein]

Originally Posted by Alan L

They will probably tend to freeze on over time - so you can expect erroneously high values of torque if the nuts have been in place for a while - Waynes book suggests 23 ft/lb.
Mine were slack by 3-4 ft/lb.
Alan

Anderson says 29 ft/lbs with Dilavar.
Yes, it's tough to estimate break away torque but the point is they didn't need re-torque.