Quote Originally Posted by TomL View Post
Interesting, all my reference material on the valve size(intake only) say 1.825" 58 to 69 and 1.935" 70 to end of production. These numbers do not convert to a standard fraction but 1 7/8 and 1 15/16 are used. I do remember the confusion about 20 years after the 72-73 bastid head bolt-cylinder bolt pattern started showing up for rebuild at shops, mine included!
You may very well be correct Tom - I'm going from memory and it was a long time ago. I do know for certain that we go-fast guys did change these larger intake valves to the XLR valves (which were a real 1-15/16") because of the tulip shape and how this shape aided airflow into the intake the track, which we invariably ported. The 1-3/4" XLR exhaust valves were also installed, as they were shaped as well.

Yes, that 1973 cylinder/head combination was a winner! I com pained about finding my 1970 heads - but the guys doing 1 1973 have a much tougher time!