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Stroke of crank for 1970 Trans Am Motor

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DAMX View Drop Down
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    Posted: Jan/12/2022 at 9:20pm
A history question here: What stroke was used in the 1970 Javelin Trans Am motors? I know they were allowed to de-stroke to get to 5.0 litres. Just asking because I might consider building a 1970 Javelin for the SVRA Vintage Trans Am series if they will allow tribute cars.

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Dono
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Javelin_GT Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2022 at 9:07am
2.906

Very rare but I have found 2 over the years.  Wayne Davis has one in this TA Javelin.  The other is in my garage.

Of course you could have one made but not cheap.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote DAMX Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2022 at 11:31am
Thanks for the information. Since it will be an actual race car I don't need a motor that has heritage. Blow ups are very possible on track. The motor just has to be built to the rules. It will not be a show car. 

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Dono



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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2022 at 1:43pm
If I may, best power is the goal, 305 cubic inches is the limit.
For best "flow" in & out of cylinders for most power, a 4.00" Plus Bore is "wanted".
GM & Ford both produced & offered to the public in cars 302 V-8's with 4.00 inch bores.
AMC did NOT !  Pre '70 they were small 3.78 bore 3.28" 290/343 stroke motors.
In 1970 TransAm rules changed allowing stroking, so AMC started using 4.08" 343/360 bore blocks with a de-stroked 2.906" stroke crank to get the rules dictated 305 CI limit AND a 4.00+ Bore...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2022 at 3:44pm
Just so you don't get the wrong idea, AMC did not furnish 343/360 blocks to Penske or Traco for the 70 Trans Am Javelin cars.

What they did supply was a special block with no displacement ID cast on the block. The blocks had provisions for four bolt main caps (full main webs).

Wayne Davis did not use a 343/360 block to build his 305 cid race motor.

IIRC correctly Barry Allen Race Engines did the work for Wayne Davis.

If you really want a true competitive race motor, you should start by contacting Wayne Davis or Barry Allen. Anything less will probably just get you confused.


Edited by White70JavelinSST - Jan/13/2022 at 3:46pm
70 Javelin SST, second owner, purchased 1972
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Javelin_GT Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2022 at 5:06pm
I also sold Wayne the block for his engine.  Barry did not add the 4 bolt main caps.  

If you found a short stroke crank you could put it in a production 360 block.  

Along with Waynes engine I know of two other 5 liter race engines he built.  If you are serious about building an engine I would call Barry and pick his brain.




Edited by Javelin_GT - Jan/13/2022 at 5:09pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mstrcrftr Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2022 at 5:10pm
Originally posted by White70JavelinSST White70JavelinSST wrote:

Just so you don't get the wrong idea, AMC did not furnish 343/360 blocks to Penske or Traco for the 70 Trans Am Javelin cars.

What they did supply was a special block with no displacement ID cast on the block. The blocks had provisions for four bolt main caps (full main webs).

Wayne Davis did not use a 343/360 block to build his 305 cid race motor.

IIRC correctly Barry Allen Race Engines did the work for Wayne Davis.

If you really want a true competitive race motor, you should start by contacting Wayne Davis or Barry Allen. Anything less will probably just get you confused.

A few years ago barry allen actually built an amc high performance engine using a 401 block.  The results of what he got out of were amazing for what he had in the build.  If i remember right it was in hot rod magazine.  I think ten years ago or more
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mramc Quote  Post ReplyReply Direct Link To This Post Posted: Jan/14/2022 at 1:41pm
Ok, to give you a complete answer to the original question, for 1968/1969 Trans-Am rules were that the stock block had to be used so Ronnie Kaplan  had to use the 290 AMC V-8 block. They used a bore of 3,842 (3-13/16 + .030 ") with a  stock stoke 3.28" .
Donohue and Penske according to Donohue 's book "The Unfair Advantage" the rules for 1970 and 1971 allowed then to use what amounts to a 360/401 service replacement block based off the 360 . The difference was since Donohue had raced both Ford Mustangs and Chevy Camaros in the Trans-AM races both used a 4.0' bore and 3.0" stoke so since that is what worked that what they used for the AMC Trans-Am engines. Because that what had worked for them.  And they got under bored AMC service replacement block. I had a NASCAR block with a 4.04" bore instead of the 4.08" bore , so I know they did do such things. LRDaum
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Javelin_GT Quote  Post ReplyReply Direct Link To This Post Posted: Jan/14/2022 at 4:59pm
Originally posted by mramc mramc wrote:

Ok, to give you a complete answer to the original question, for 1968/1969 Trans-Am rules were that the stock block had to be used so Ronnie Kaplan  had to use the 290 AMC V-8 block. They used a bore of 3,842 (3-13/16 + .030 ") with a  stock stoke 3.28" .
Donohue and Penske according to Donohue 's book "The Unfair Advantage" the rules for 1970 and 1971 allowed then to use what amounts to a 360/401 service replacement block based off the 360 . The difference was since Donohue had raced both Ford Mustangs and Chevy Camaros in the Trans-AM races both used a 4.0' bore and 3.0" stoke so since that is what worked that what they used for the AMC Trans-Am engines. Because that what had worked for them.  And they got under bored AMC service replacement block. I had a NASCAR block with a 4.04" bore instead of the 4.08" bore , so I know they did do such things. LRDaum

I have a crankshaft with a 3" stroke.....so who knows what they may have been trying to do.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jan/16/2022 at 7:19pm
The reason AMC changed what they were doing to come up with a 305 / 5.0 Liter engine is because TransAm CHANGED the RULES for the 1970 Season allowing companies to change the STROKE.
Prior to that TransAm Rules DISALLOWED changing factory stroke, but allow altering the Bore.
Thus AMC was "stuck" with 3.28" stroke as was stock in the 290 & 343,
and HAD TO USE the 3.28" stroke and change bore to achieve the 305 CI Limit.

Once TransAm changed the rules for 1970, AMC changed what they were doing because obviously a 4.00"+ Block Bore flows better than a sub 4" bore...

AMC stuck with the stock 4.08" bore and de-stroke to whatever was needed to result in 305 CI
but AMC never made & sold to the public in production cars a 4.00"+ 304 / 305 CI engine...
UNLIKE both Chevy & Ford which both did...
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