69' amx

[Jeff Lee]

You have it right except I really don't think the -291 head for 1970 was a part of the equation. If it were, AMC would have sent a pair of heads out with the body parts. I have a LOT of AMC correspondence on the conversion issue and have never seen even a hint about newer heads on the horizon.
I think the only deal was to have a fresh face for the 1970 model year.

[Paul Ceasrine]

Jeff,
Your probably right. Maybe it was just the 70' nose looked better than the 69'.
From an AMC marketing stand-point, the new-style was the way to go.
The new 'dog-leg' heads would only work, if they went through 'Crane' for
modifications.
Maybe AMC's original thought was to try to back door the newer heads
on to the 69' S/S cars, after they were converted to 70' cars.
Greg Long of AMC (Elmsford HQ), said, he thought that AMC would be willing to build (7) 70' AMX S/S cars (in January 70') with the new style heads. Once out there, they would push the 70' conversion kits for the 69' S/S racers.
PC

[tbenvie]

AMC sent the upgraded 70 kit to the SS/AMX owners purely as a marketing idea. The 70 AMX had a big facelift-nose, taillights, interior, and wanted to promote the new 70 model line. The heads were also much better, and larger head bolts as well, but this was never part of the upgrade. Didn't other manufacturers change grills/taillights as well to upgrade to a newer model year?

The improvement of the heads was not done by Kaplan, but rather in-house by the engineers that ran the flow bench and other testing equipment. They tried to sell the idea to AMC when the 390 came out-and improvement that actually cost no extra money, just a redesign casting. One of the engineers actually raced an original SS/AMX at the Nationals-the purple one shown in the staging lanes. he later helped write Performance American Style, a early "bible" for AMC enthusiasts sold at the dealers parts counters. AMC and Hurst redid the original set of heads used on the prototype Super Stock car, but did not have the time/facilities to do a run for all the cars, so sent them to Crane.

Spoke to the original owner of an SS/AMX yesterday. He also swapped the parts to an upgrade 70, but as he only raced at a local track he did not have to change them back.

[Jeff Lee]

Good point to Paul about the head bolts. The 1970+ blocks / heads were a 1/2" head bolt while the 1969- blocks / heads were a 7/16" head bolt. Putting the 1970 heads on the 1969 short block would have required reducer bushings in the heads or drill / tap to the block.