Are these swirl ports?
I see Shepard groups the 308/576 heads together but no mention of the 923 head we are talking about. I read the head chapter in Shepard's book and saw no mention of "all LA heads are swirl port heads" as quoted in post #29 above. In fact Shepard mentioned the #302 as being the first with a swirl port design. He also said it's the only head with a "true heart shaped chamber". He must not have paid attention to the 273 heads. In fact the #080 head on the 64 273's was a heart shaped closed chamber head. I have a pair of 302's and a pair of 920's and both have a "heart shaped chamber" The only thing the early heads don't have is that little brow in between the valves like the 302's have. I guess it's just a difference in what your definition of heart shaped is.
