Quote:

273s and 318s used the same heads---- port size and all.



Sort of

64-66 273 had a weird intake bolt anfle but the same ports and other bolt patterns and they were small closed chambers. I think they were a 315 casting#.

67 318 and 273 both used a 920 casting head that was closed chamber and virtualy identicle to the 315 except the now more common intake bolt angle.

68-69 they again shared the same head and it was an open chamber head that except the casting number and AIR ports was pretty much unchanged til the 302 casting in 85

I am not causing global warming, I am just trying to hold off a impending Ice Age!