[Fot] Re-torquing a cylinder head - GT6

Wed Sep 20 10:27:44 MDT 2017

I called ARP.  They say (contrary to some other sources I looked at) always re-torque a cold engine, not hot.  The advice was to back off the nuts and re-torque one at a time, same pattern as when the head is first installed.  The reason for backing off first is that the in-place “break-away torque” may be higher than the desired torque setting, i.e., there’s friction from breaking loose a static connection that may exceed the original torque setting.  Trying to tighten from the as-is position may give a false reading that’s higher than the desired torque setting. 

I asked about re-lubing -  the indication was that’s probably not necessary, unless you are dealing with an engine that has been sitting a long time or run many hours and had the original lube bake off, and that’s not likely to be the situation when we are all re-torquing the head.

Thanks for all the feedback!

Scott

On Sep 20, 2017, at 6:46 AM, barry rosenberg via Fot <fot at autox.team.net> wrote:

Contact Mr. Gasket. They make the Payen gaskets and have a great tech department you can easily talk to. Ask them.

Barry

On Wednesday, September 20, 2017 3:48 AM, Edward Dunn via Fot <fot at autox.team.net> wrote:

Excellent analysis, Dr. Dunst...

What advantage would a different gasket material have, say... copper? 

Edward Dunn
President

Quality Fuel Trailer and Tank Inc.
4580 Klahanie Drive SE
Suite 423
Sammamish, WA 98029

425-526-7566   x 7012

-----Original Message-----
From: Fot [mailto:fot-bounces at autox.team.net <mailto:fot-bounces at autox.team.net>] On Behalf Of Mordy Dunst via Fot
Sent: Tuesday, September 19, 2017 9:51 PM
To: fot at autox.team.net <mailto:fot at autox.team.net>
Subject: Re: [Fot] Re-torquing a cylinder head - GT6

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
Triple R Munitions, Inc 626.201.9471
T FFL 6,7 SOT 2

On Tuesday, September 19, 2017, Scott Janzen via Fot <fot at autox.team.net <mailto: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.

_______________________________________________
fot at autox.team.net <mailto:fot at autox.team.net>

http://www.fot-racing.com <http://www.fot-racing.com/>

Donate: http://www.team.net/donate.html <http://www.team.net/donate.html>
Archive: http://www.team.net/archive <http://www.team.net/archive>
Forums: http://www.team.net/forums <http://www.team.net/forums>
Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/gasket.works@gte.net <http://autox.team.net/mailman/options/fot/gasket.works@gte.net>

_______________________________________________
fot at autox.team.net <mailto:fot at autox.team.net>

http://www.fot-racing.com <http://www.fot-racing.com/>

Donate: http://www.team.net/donate.html <http://www.team.net/donate.html>
Archive: http://www.team.net/archive <http://www.team.net/archive>
Forums: http://www.team.net/forums <http://www.team.net/forums>
Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/edunn@qualityfueltrailers.com <http://autox.team.net/mailman/options/fot/edunn@qualityfueltrailers.com>

_______________________________________________
fot at autox.team.net <mailto:fot at autox.team.net>

http://www.fot-racing.com <http://www.fot-racing.com/>

Donate: http://www.team.net/donate.html <http://www.team.net/donate.html>
Archive: http://www.team.net/archive <http://www.team.net/archive>
Forums: http://www.team.net/forums <http://www.team.net/forums>
Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/britcars@bellsouth.net <http://autox.team.net/mailman/options/fot/britcars@bellsouth.net>

_______________________________________________
fot at autox.team.net

http://www.fot-racing.com

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/sjanzen@me.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/fot/attachments/20170920/8122d766/attachment-0001.htm>