[Supras] ARP-2.2 mm Cometic head bolt retorquing

[Jim Jobe]

Hmm, I'd be concerned with what you've done on the retorque.  Firstly,
there's a reason why every torque wrench has stated in the manual that
it should not be used to remove a fastener.

>From wikipedia: "For a given pair of surfaces, the coefficient of static
friction is larger than that of kinetic friction."

http://en.wikipedia.org/wiki/Coefficient_of_friction

Basically, the reading is inaccurate and useless, and this typically
leads to damage of the wrench as it is stressed well beyond
it's intended capacity.

Also, when you stated that after loosening three of the nuts
that "virtually no tightening was required, even up to 90 lb-ft"
suggesting you did not loosen them enough to get enough movement
when tightning to get an accurate torque reading.  So now you
have potentially three nuts undertorqued.  I recommend you properly
retorque the head by loosening each fastener approx 1/16th to 1/8th
of a turn and tightening back up to your torque of choice in the
proper order stated in the manual (alternating pattern from the
inside out).  Make sure each fastener has some movement as it is
tightened and as the desired torque reading is approached.  I prefer
to use a recently calibrated beam wrench over a clicker for this
process.  Finally, as ARP recommends I would torque each fastener
to full torque 3-4 times to properly mate their threads.  Hopefully
you did this during the initial build up.

ARP has some excellent articles on their website about fastener
torque and clamping force.

On Sat, Oct 27, 2007 at 10:38:57PM -0400, berniek at technicaldevelop.com wrote:
> Rockey and group:
> 
>     Just got done pulling the top end of the engine apart and first 
> removed the cam cover on the exhaust side after about 50 miles and maybe 
> 10 temperature cycles.  The ARP nuts were tight.  They cracked slightly 
> when loosening them with a torque of about 80-90 lb-ft.  When 
> retorquing, virtually no tightening was required, even up to 90 lb-ft.  
> I tried about 3 nuts, two in the center and one at the front end, and 
> they were all the same.  After seeing that, I did not bother to remove 
> the intake cover (difficult due to fuel pressure gauge  in the injector 
> rail and dual injector connectors.  Left the stock ones in place "just 
> in case" and spliced in the Greddy connectors). 
> 
> 
>     I still wonder, though, if in time the indentations the gasket will 
> make in the head and block from thermally induced relative movement will 
> make retorquing necessary in the future.  Guess I might take a look at 
> this again at perhaps 10K miles.  In the meantime, on to 14 PSI boost. 
> 
> 
>     As always, comments would be appreciated.
> 
> 
>           BernieK
> 
> 
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