GM head gasket

[GaryL]

I used the .028" GM composite head gasket. Do they require re-torqueing?

[Jerry@CHP]

No they do not.  You're probably using the 10105117 gaskets??  Only the steel shim gaskets need to be re-torqued.  Z28s used the 3830711 gasket, it's about .019".   

Jerry

[GaryL]

Thanks. The 10105117 is the one I am using. You suggested I use these.

[olympic69]

Out of respect for his experience I dont want to dispute what Jerry says, but in the event he was in error I quote from the 1994 Chevy Power book P. 67 ( it is dated),

"Steel shim gaskets do not require retorquing. Most composition gaskets ( except PN 10185054) should be retorqued (either hot or cold) after the engine is first warmed up."

PN's 10185054 and 12363763 are specifically listed in the 2001 GM Performance Parts book as not requiring retorquing. I guess things may have changed in the interim- I am just quoting the General, and if JM made a typo direct you back to the source, that being General Motors, and make sure GaryL does not mess something up!

Cheers 

[Jerry@CHP]

Have done this many times on the dyno.  If you use the GM "711" steel shim gaskets, you do need to re-torque them.  The head bolt torque does change.   Any respected engine builder will tell you this too.  In one of my other Stock Eliminator engines, I have the 10105117 gaskets to get the proper deck clearance.  When checking this gasket after breaking in the engine, we have never found a change in the head both torque.........65-70 lbs.  I'm just speaking from engine building experience and years of dyno time.  Ask the engine builder in your area.

Jerry 

[68Zproject]

So the original Z28 gaskets had to be retorqued?

[JohnZ]

So the original Z28 gaskets had to be retorqued?

No, not in production - all the head bolts were torqued simultaneously with an air-powered multiple-spindle automatic nutrunner, and they weren't touched again. In the 60's, that was considered "good enough".