I rebuilt the 250 in my 66C10 and now I'm trying to start it. When I crank it over it spins like it has no compression. When I adjusted the valves, I used the two full turns after chatter stops at TDC as the shop manual shows for a 66 250 engine. Recently it occured to me that the engine in my truck is a 71-73 250 that was transplanted in sometime in the past. My question is, could the "two turns after chatter stops" valve adjustment of the 66 engine work on the 71-73 engine or should it be one turn?