[RICK LAKE]

Tom Cimino Tom Those specs are for mostly iron motors. I don't tighten my heads on either an aluminum headed motor or complete aluminum motor. 75 -80 ft pounds is more than enought for a torque reading, unless you are running 15-1 compression. I am going with you are using 1020 felpro gaskets. Did you spray any kind of sealer on them?? If not that after you run the motor for a couple of heat cycles, retorque the heads to 80 ft pounds. I have studs from ARP on all my motors. The motors with Aluminum heads get about 20% less torque specs because of these things
1 Aluminum expands and retracts more than iron.
2 Aluminum will crush where the bolts are being torqued at.
3 Do you have wide washers to help distribute the torque under the bolts
stud setups come with harden flat washers to help this.
4 if you look at what you typed about 63-67 427 motors, they didn't have aluminum heads back then and if they did where not torqueing them to 100.
5 I have been told by machinist that aluminum expands about .0012" as to where iron is .0006-8" It's a differents.
6 IMO I would rather loose a head gasket from an internal problem like hyroloc than break rods and crankshafts.
IMO don't tighten any more and assembly the motor and break it in. Put some miles on it and JUST recheck the all the bolts for around spec. Like I said, aluminum doesn't need the same torque spec as iron.
Tom my shelby motor is 13 years old and on the second build. All Aluminum. No failures of the gaskets only rocker arm shafts. GM now has a yield to torque numbers as specs for motors with, get this stretch head bolts. torque to 20 pounds and 155 degrees to spec. Works out to about 68 ft pounds. I hope this helps. Stay where you are for now. Recheck in 500 miles.