Updates and corrections:
Okay, by brother corrected me on the head torque points(difference between
theoretical and practical). On older cars (like ours) if you use the new head
gaskets then you dont have to retorque the heads. Unlike the theoretical
application of bolt technology (like I learned in college) the bolt has much
less to do with seating the head than with the gasket. On older Datsuns -
twenty to thirty years ago, then yes, you did have to retorque the head bolts
every 30,000 miles. Same technique as I outlined in my previous message,
though. (Okay, thats ONE for me - my brother tends to preach to me!)
He also says that yes, if you are going to retorque the head you must loosen
the bolt first and then go ahead and retorque it (although its mute, since you
dont retorque anyway).
Further, this only applies to foreign cars(he mentioned Nissan and others).
Many domestic manufacturers Ford and GM, us torque-to-yield head bolts. These
are single use bolts ONLY. Ford started using these when they thought they had
head warping problem they tried to fix using these types of bolts. My bro
reminisced about how many snapped head bolts he had to removed form Ford blocks
because the engine overheated and snapped the bolt off in the block. This just
means that if you have a car that uses these torque-to-yield bolts, you cant
reuse them - as you can on our cars.
So in short - no, you dont have to retorque the head if youre using these new
(non-asbestos) head gaskets.
Perry Smith
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