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Old 07-13-2010, 07:50 AM
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Modern engines? Torque and forget. Most of the latest engines use torque-to-yield bolts that can only be used once anyway. Don't like those!! Like most things, they are easier/quicker for the manufacturer to install (can use automated equipment), that's the main reason for them.

The only engine I know of that REQUIRES retorquing even with modern head gaskets is the old AMC/Rambler 196. DO NOT confuse this with the 64+ 199/232/258/4.0L -- they have no problems!

We (us AMC/Rambler guys) also figured out WHY it eventually loosens the head bolts! The head is rather massive for a small six and expands and contracts by 0.020" every heat cycle. That eventually backs the bolts out enough to blow the gasket -- running hot is the first indication, and the head usually warps a little. Now they are old (last one made in 65!) and have been run hot a few times already, so they have a nasty tendency to crack now, and good heads are getting hard to find.

This engine is a flat-head conversion. The head can't be bolted to the old flat-head block because AMC changed the right side of the block casting where the valves were in the flat-head. From the top of the side covers down and on the left side of the block it's identical to the flat-head, but that top right side is different and the bolt pattern for the head is different. The head has the intake built in with an aluminum cover plate. The large mass of cast iron alone is what causes it to loosen the bolts over time. Has to be retorqued every other year/12-15K miles or it will eventually blow the head gasket. Don't know how long/far it will go, but the valve cover has to come off to adjust the solid valves at about those intervals anyway.
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