[RICK LAKE]

Fatboy Couple of ideas I have and you need to check first,
1 Was the heads or block milled? Are all these parts new when the motor was built?
2 Need to pull drain the motor and pull the intake bolts out and check the angles of both heads and intake manifold sealing surfaces. Check in here for another thread about limit for sticking a feeler gauge between the 2.
3 4 th set of gaskets, Did you try HigH-tAC SEALER? Spray on a couple of coats and let dry. Spray on a lite coat and install on the heads. Center the holes on the heads. All surfaces must be cleaned. get another person to help center manifold on motor. install studs in the heads on all 4 corners around coolant passages. Rest of holes can be bolts with washers. Go in 5 pound incromints of torqueing down manifold. I think the spec is 35-38 ft pounds. Allow this to cure for 24 hours. Start motor and run for couple of minutes and let cool. Do this a couple of times (3) . Retorque manifold bolts and nuts. Go road test and recheck. If you still have a leak the manifold is porous. need to pressure test and seal or weld area to seal. If this problem happens, you might want to sent the manifold here to Joe Craine and let him works his magic for repairs and porting. Does great work. Good price and the part looks like jewelry.
You already use RTV gasket. Stay with th silver color stuff and give it 24 hours to cure.
What is the material of the heads and block? Aluminum and iron? Aluminum and Aluminum? Iron heads and aluminum block? Here's the thing there are different expandsion ratios of these metals heating up. This may also cause the creeping of the gaskets. Retorque will only work 2-3 times. Rick L.