you always bring things up in steps...
like on head bolts.
what steps are should be used is often specified.

the waiting overnight to torque 928 headbolts , could have been about
letting the head gasket settle..
and not about the bolts so much.

were they stretch head bolts, or non-stretch type ?

but yes..always in steps, that's only logical and natural.
especially when it's multiple fasteners in a group.
like on a cylinder head say.

----- Original Message -----
From: "Don Hanson" <dhanson928@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, September 27, 2011 9:33 PM
Subject: Re: Torque Specs - Lug bolts and nuts

> On Tue, Sep 27, 2011 at 8:51 PM, Gary Bawden
> <goldfieldgary@gmail.com>wrote:
>
>> Snipped.
>>
>> I believe the engineers know this, and set torque values to a number that
>> they believe will do the job, without over-stressing the part. And as has
>> been pointed out by others, it's the uniformity of torquing fasteners (at
>> least on parts having more than one) that is probably more important than
>> the actual torque value.
>>
>
>  One thing to keep in mind about torquing something to specs....Depending
> on the parts connected by the torqued nuts, bolts, studs, whatever....they
> should often times not be taken right to the specified torque, all in one
> tightening.   When I do alloy wheels up to 100lb/ft....I go round to about
> 80 in a star pattern, then I re-set the wrench and do it up the final
> 20lbs.
>
>  My engine  mechanic used to take two full days to torque the heads on the
> 928 motor....he would (I don't have exact numbers) torque em up to about
> 50%
> and leave em all day, then come back and go to like 80% and leave em
> again.
> then again with a 'resting, settling period' and finally go to full
> torque...
>
>  Castings seem like they are pretty brittle, somewhat fragile...If you are
> to torque say a water pump to (out of thin air, this figure) 30ft/lbs....I
> wouldn't feel right just doing it up, one fastener at a time, right to
> 30lbs...I'd probably snug it up, then torque to 20, then go back and go at
> it with 30ft/lbs....minimize and spread the stress.