Reply To: Series 81 Torque Specs

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Mike,

For your aluminum head (correct for all Series 81 and for the last 600 Series 80s), I’d go 5 lbs below that recommended for iron heads. For my two S80s with iron heads, I use 60-65.

For both, it’s important to use a dental pick or similar tool to clean and debris from around the base of the studs where they emerge from the block, so that the gasket will seat well in those areas. I also use an aerosol copper coating on both sides of the head gasket.

Torque pattern: No specific pattern was recommended in those years. I start with the center stud in the center longitudinal row, then the two outside studs (left and right) adjacent to the first one. The next two are the center-row studs just outboard, front and rear. Then I go diagonally (e.g., right rear, left front, left rear, right front) adjoining the two center studs just torqued. Use the latter technique for the remaining studs. I may be ‘way too particular, but my first pass is at 35 lbs/ft, then 45, then in 5-lb increments from there. Do the final torque reading (55/60, as you prefer–but no more than 60), TWICE.

Note well Bill Rolapp’s comment: Never re-torque when engine is hot–re-torque only when the engine has cooled sufficiently so that it’s not uncomfortable to put the palm of your hand on the head for 10 seconds. I prefer to re-torque at least three times, and you will still get some movement of the nuts on the 3rd re-torque.

George