69' amx

[Tom Goldman]

The '69 AMX 390/ 315 has always been a 10.00 factor right at the top of E /S and SS/I.........At one time , the SS AMX engine was the most heavily factored HP in SS , even more than the Hemi's and BB Chevies@75 HP over the rated HP .......Tom

[Paul Ceasrine]

The article about the special "Crane" heads for the 69' AMX S/S car,
was that they utilized Mopar 440 valves.
The 69' 'Crane' heads were good, but in 1970 the 'dog-leg' design
exhaust ports flowed much better, than the flat-style 69' heads.
Does that sound correct Jeff.
I guess, AMC wanted to utilize the 70 'dog-style heads' for the 69 S/S cars,
but could not.
They would have to build another (50) 70' AMX S/S cars. Instead they offered 70' front-end conversion kits and replacement trim components and dashboard units. NHRA would not legalize that conversion, due to the
fact that the 70' AMX frame had a longer wheelbase than the 69' car.
I think thats in the ballpark.
Either way, AMC got somewhat screwed.
PC

[Jeff Lee]

Wheelbase for 1968 - 1969 - 1970 AMX's are all the same, 97". You may be confused in that the overall length changed a few inches as a result of body overhang. But the wheelbase remains the same on all 2-seat AMX's.

I assume AMC sent out the 1970 sheetmetal, tail lights, dash, seats, etc. (even a 1970 VIN plate!) to the owners of the original 1969 SS/AMX's more because they wanted a new for 1970 product in front of the public.

The 1970 production heads are an improvement over 1969 and earlier production heads but in a SS application back then, I believe the 1969 ported Crane heads were better than a 1970 production head (remember, this was back when SS did not allow porting). Note: AMC did not send out new "dog leg" 1970 cylinder heads to the racers, only body change items.
The SS/AMX's were fast right off and continued to be so well into the 1970's. Several years ago the dog-leg cylinder head was approved as a superseded part; long after the cylinder head porting rules took affect.

The fact is, AMC was the poorest of the auto manufacturers. They could not justify building another 50+ cars (at a loss) in 1970. So they thought they could get around the NHRA mandate that all cars be "assembly line produced" by replacing the relevant parts with full corporate approval. Again, note AMC provided NEW 1970 AMX VIN plates! Clearly, this was the intent of the manufacturer that 1970 AMX SS cars were to be recognized and raced along with 1969 SS/AMX's. But rules are rules and once NHRA saw what was going on (and it wasn't a super-secrete deal either), they put a stop to it and advised all racers that if they wished to race an x-ram AMX then it would be a 1969 model. Numerous owners who made the conversions with AMC's blessings along with new paint jobs, parked the cars in disgust (gee, does anything ever change?). A friend of mine has one of those cars. It was raced in 1969, converted per factory recommendation and subsequently parked. The only good thing is the 1970 VIN plate allowed easy MVD allowance for this once "race only SS package car". The car accumulated 70,000 in street miles before my friend bought it and restored it; back to race day 1970 with 1970 parts still intact. It is #3 of 52 produced.

Now, however, an interesting argument could be made to re-instate the 1970 AMX as a x-ram car due to the new "crate motor" cars in S/SS.
This was, and no doubt about it, AMC's intentions.

[Paul Ceasrine]

Jeff,
You couldn't have described those details any better.
I always figured, that after the factory cars suprised everyone at the 68' Winternationals, they would not let the factories per say, run the show.
ie; (Not 50 produced)
68' Cobra-Jets (not factory-production until April 68)
68' GSS 440 Darts (just who had them in January 68')
340 Cuda's and Darts (factory rated at 275HP)
Even the 67' R/O Plymouth's and W/O Dodges (does anyone really believe there were 55 of each produced)
They started cracking down, just before the 68' Springnationals. Made Plymouth and Dodge show the sales documents for 50 sales (each) of the factory SS/B Hemi cars. They were made legal about a week before the June event at Englishtown.

[Tom Goldman]

Jeff has it right. ...There is a '69/'70 down near Lancaster ,Pa. .....the owner showed me the documentation.....The later '70/'71 3196291 head casting superceeded the original rectangular port heads, I believe in the mid '80's ..............I have an original, damaged, Crane head . The porting was nothing spectacular by todays standards, but in '69 it was probably better than the best Modified Elim heads ......Tom

[Dwight Southerland]

Maybe you don't know that Crane offered ported & polished cylinder heads in their catalog during this time period. There were two versions of SBC heads that could be purchased for around $500. Many Modified racers ran those heads in the late '60s & early '70s. Crane had a production facility set up to manufacture the heads in quantity so it makes sense that AMC contracted with them for the heads. Very much cheaper than new castings.

[Tom Goldman]

I knew about the Crane Chevy heads, but didn't realize they were available as early as '69. .....I always thought they were from around the mid '70s. ...I remember the speed shop I delt with getting a set for a twin turbo Don Hardy Vega the owner was building around '75. ........Make you sad to think of the fate of a company like Crane, that pioneered so many things........AMC did make some very special head castings for the NASCAR program. ....I managed to have 2 sets of these over the years,and thy did some things that were not seen on aftermarket heads till many years later. ....The intake floor and roof were raised up substantially , the top of the intake runner was flush with the valve cover rail. ....The decks were about .125 thicker than a production casting. ...the finished set I had came from Traco ,and were angle milled 1.5 deg, giving the head a 16 deg valve angle and a 42cc chamber,and a 230 cc intake [178 stock] in 1974 !! ..........Tom

[Tom keedle]

Originally Posted by Jeff Lee

Wheelbase for 1968 - 1969 - 1970 AMX's are all the same, 97". You may be confused in that the overall length changed a few inches as a result of body overhang. But the wheelbase remains the same on all 2-seat AMX's.

I assume AMC sent out the 1970 sheetmetal, tail lights, dash, seats, etc. (even a 1970 VIN plate!) to the owners of the original 1969 SS/AMX's more because they wanted a new for 1970 product in front of the public.

The 1970 production heads are an improvement over 1969 and earlier production heads but in a SS application back then, I believe the 1969 ported Crane heads were better than a 1970 production head (remember, this was back when SS did not allow porting). Note: AMC did not send out new "dog leg" 1970 cylinder heads to the racers, only body change items.
The SS/AMX's were fast right off and continued to be so well into the 1970's. Several years ago the dog-leg cylinder head was approved as a superseded part; long after the cylinder head porting rules took affect.

The fact is, AMC was the poorest of the auto manufacturers. They could not justify building another 50+ cars (at a loss) in 1970. So they thought they could get around the NHRA mandate that all cars be "assembly line produced" by replacing the relevant parts with full corporate approval. Again, note AMC provided NEW 1970 AMX VIN plates! Clearly, this was the intent of the manufacturer that 1970 AMX SS cars were to be recognized and raced along with 1969 SS/AMX's. But rules are rules and once NHRA saw what was going on (and it wasn't a super-secrete deal either), they put a stop to it and advised all racers that if they wished to race an x-ram AMX then it would be a 1969 model. Numerous owners who made the conversions with AMC's blessings along with new paint jobs, parked the cars in disgust (gee, does anything ever change?). A friend of mine has one of those cars. It was raced in 1969, converted per factory recommendation and subsequently parked. The only good thing is the 1970 VIN plate allowed easy MVD allowance for this once "race only SS package car". The car accumulated 70,000 in street miles before my friend bought it and restored it; back to race day 1970 with 1970 parts still intact. It is #3 of 52 produced.

Now, however, an interesting argument could be made to re-instate the 1970 AMX as a x-ram car due to the new "crate motor" cars in S/SS.
This was, and no doubt about it, AMC's intentions.

wouldn't they have had to change the frt suspension too?
68-69 was different from the 70 amx's..

[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

[Jeff Lee]

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

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).