273 copper head gaskets SCE

After the first fire up I checked the timing and it was way off like the distributor moved alot . 13* initial , 14* mechanical, 27* total.. I strongly believe this why the head gaskets blew 2 times. DETNONATION. never heard any signs of pinging even when lugging it in 3rd gear ... dist advance can hooked up . timing should have been run at 34* total ... 20* initial 14* mechanical.
Advanced timing can lead to detonation, retarded timing usually results in poor performance and hotter coolant temp.
I was curious if the directions said to retorque.