Jim,you're up early or late
I do have access to a dyno,the shop doing the machine work has a modern unit. When I complete the engine assembly,it's going on the dynometer for break in ,then jetting and timing power adjustments.I do electrical work for the shop owner in exchange for some of the machining and dyno time.
Slight dish?
120 cc head,12.8 cc's for the .060 head gasket,piston at zero deck,4.030 bore,4 inch stroke,do the math.Bring the piston up .020 above deck,do that math,just barely 7-1 actual compression.Yes, I did cc the combustion chamber.This ain't no low compression blower motor.
The GMC 302 D head is far better than an old Chevy 6 but nothing special in stock form,very similar to a Mopar B block head.
The rest of the engine is basically idential to a Chevy in design, 4 main bearings,coolant flow,bearing sizes.
I'm no expert,I build engines in my clay 140 year old clay floor cellar on an old engine stand,haul them up the cellar walk out and out to my dimly lit barn on a pallet dragged by a Jeep.
My 261 runs darn good for what it is,I have no doubt this GMC will very well thank you.
