I never re-torque heads. BUT, when I install them, I follow the
manufacturers recommended pattern, (from the center out), and do so
sssslllloooowwwwllllyyyyy. If you use a "click" type especially. When
complete I repeat the pattern. If even one bolt turns, I finish the
sequence (pattern) and repeat. I do so again until I go through the pattern
twice without bolts turning. Doesn't take long, compared to pulling the
cover off to re-torque. I worked in a garage for several years, dong
reparis on the local phone company fleet, and never had a head gasket fail.
Torquing is actually a measure of bolt stretch, but there is no way to
measure the increased length of a head bolt, so they use the resistance to
torsional twist. The newer head bolts in many cases are torque to yield
bolts, because the stretch actually permanently deforms the shank of the
bolt. If you took a new torque to yield head bolt, and compared it to a
used one, you could measure a slight difference in both length, and diameter
of the bolt. This permanent stretch allows for heat expansion, and
different heat/cool rates between aluminum heads and cast iron blocks, while
still firmly holding the head in place.
Enough long winded stuff. IMHO, torque carefully once, take your time, and
forget about it.
Bob
1966 1600
1970 510 4door Ice Racer
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