#270 blocks in COPOs?

[Keith Tedford]

I must be one of the lucky ones to have the original drive train. Most L78 and L72 engines, that I have heard of, died from dropped valves. This is what happened to our L78 car as well. The valve springs were too weak for over 6000 rpm use. The valves could not keep up with the valve train. They would slam shut at high rpm and eventually pull the keepers through the retainer. I was told that the COPO 427s were honed to the outer clearance limits allowing the engine to rev feely at higher rpm. 7200 rpm was effortless. Ask Peter Simpson who should know as well as anyone about the abilities of these engines. As far as casting numbers. There probably was an overlap of numbers during transition from one design to the next. The switch from closed to open chamber heads on the L88 Vettes was a rolling production change during the year. I was told that the L88 Vette that Beare Motors sold in '69 came with closed chamber heads when they were supposed to have open chambers. If we come up with enough information, patterns will emerge.