Quote:
Originally Posted by Paul Ceasrine
Jeff,
Wasn't the issue, that the 70 'dog-leg' exhaust port design flowed
better than the 69' exhaust port design, and AMC wanted to get them out there (supposedly an additional 25+ HP) over the 69' heads.
And that the 70' heads were to be prepped by Crane (ported and tricked-up).
AMC wasn't about to build 50 more 1970 Super/Stockers, so they
offered the 70' upgrade kit for the 69 S/S cars, so they could utilize the newer and better flowing Crane-prepped 70' heads.
The 70' 'dog-leg' Crane heads would not be legal for the 69 s/s cars, but would be legal for 70' S/S cars
Of course, NHRA put the 'kibosh' on the up-grade kit.
Paul
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There are no communications I am aware of between NHRA or the racers to upgrade to the -291 or dog leg heads. FYI the 1969 Crane heads have a significantly larger combustion chamber volume than the 1970 passenger car -291 head volume; something around 12cc's or so. That would have required a different piston (1969 SS piston is domed) to go with the new heads if that was what AMC wanted.
The cheap / easy way out for AMC was to just change out the sheetmetal parts and carry over the engine parts.
Tom,
Yes, the front suspension on the 1970 AMC is substantially different than the 1969 AMC. I know of at least one racer that converted his '69 AMX to a '70 AMX with all the sheetmetal parts and was later advised he had to change his suspension (which he did).