FOT,
As with Michael, I found that time alone allowed for additional torquing with
composite gaskets. I first discovered this with my Norton motorcycle. The
"flame ring" gasket at the bottom of the jugs (cylinders) compressed overnight.
If you didn't wait, and installed the head, there was no going back to retighten
it. The next day, significant retightening was required. Waiting one more day
provided little or no further tightening.
When I installed composite gaskets in my TR3, I retightened the next day,
without needing to loosen first. I also retorque hot immediately and retorque
cold 500 miles later.
Jack Brooks
>As for the use of composite or composite sandwich gaskets, I've
>developed a procedure over the years that seems to minimize problems if
>the head isn't immediately retorqued, and it seems to work, since I
>haven't had any head gaskets fail. On initial torque, I take plenty of
>time between cycles of increasing torque, usually fifteen minutes or
>more. If torque would be normally split in four cycles, I let perhaps
>ten-fifteen minutes go by between each. That allows for progressive
>compression of composite gaskets. On the last go-round, I wait maybe
>thirty minutes and then do a last check to specified torque. This also
>helps greatly with used studs and nuts--if one stud or nut is failing
>because it's yielded, that shows up as a loose nut on final torque
>check. All this extra time gives composite gaskets more time to relax.
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