340 Heads

The 'J' (915) heads were used on the '70 six-pac engines with different machining and 2.020 intake valves. Also used on the '71 340's with 2.020 intake valves and '72 and '73 340's with the 1.880 intake valves. It might be more accurate to say the 360's used the 340 'J' head with the smaller intake valves. I believe the 'X' (894) heads were used on the '68 and '69 340 engines, and all 340's after that used the 'J' heads as well as the 360's until they were re-cast as '587' ...Some one might want to check me on this, my memory being what it is now (I am older than I have ever been) but I believe this to be correct... Terry.