|
"I think:
The heads without the isthmus are pre-1973.
The heads with the isthmus are 1973-1975 model heads.
The heads with double isthmus are R-Sport.
The only difference between an E & an F head is the thickness."
That may all be very true... in Australia. :-)
But in the US, I don't recall ever seeing an engine marketed as a B20F without* the isthmus. Recall an 'F' here in the US means 1972 or later, as we only got the 'E' in '70 & '71. I'm fairly certain that both (isthmus-equipped) 'F' heads I currently possess, were originally on US spec '72 B20F's.
*edited after original post to change the word 'with' to 'without'
--
Gary L - 142E ITB race car, 73 1800ES
|