Please help me identify my #6 heads. I measure the intake as 2" and the exhaust as 1 5/8". I have used several measuring tools, but not a machinists mic. I am hoping these are the more rare W31 Heads. I also bought the W31 intake from the same guy all in 1975. Is there any other way to tell if they are W31 heads? Thank You!

 

Take any #6 heads, machine them for the larger valves, and you have the "more rare W31 heads". Quite a bit easier than grinding the lower leg off the "E"...

 

Thank You Joe, Do you think a restorer of a W31 would pay more for these as originals? I don't understand the "E" comment.

 

Less than honest people have been known to grind off the lower leg of the "E" on 1970 big block heads, creating much more valuable "F" heads sold to the uninformed at inflated prices. The difference there is that the casting number is different and fakes can be easily uncovered.