[Fot] Re-torquing a cylinder head - GT6

[Mordy Dunst]

Composite Fiber gasket material has internal micro gas pockets.  Depends on the quality and repeatability of the original gasket material.   When heated the gas expands and seeps out from areas of least resistance.  Perhaps after a few heat / cool cycles all those  internal gas pockets that were present when New have been vacated.  The gasket then creeps upon itself and becomes imperceptibly thinner.  Hence the original axial tension is now reduced.  Perhaps some parts of the gasket are more inhomogeneous than others and leads to a mismatch in "torque".  

That's the nature of an inhomogeneous materials.  

Anyways that's how I put it together.  

Best 
Mordy

MDunst Headgasket.com 626.358.1616 
Fax 626.628.3777 
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On Tuesday, September 19, 2017, Scott Janzen via Fot <fot at autox.team.net> wrote:

I’m adjusting valves after the last race weekend.  For whatever reason, I put the torque wrench on a couple of the head bolts - and found maybe 90 degrees of movement on the few nuts I checked. 

I run a Payen head gasket - composite with a metal ring at the combustion chamber.

Should I:
loosen one nut at a time, lube with moly as provided by ARP, and retorque to ARP spec;
tighten from the current position to ARP spec (75 ft-lb)
do nothing

The engine has probably four race weekends on it.  I can honestly say I have never re-torqued Payen gaskets before, but I have also re-checked the torque on other gaskets and not found any movement.


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