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  1. #11
    Join Date
    Feb 2006
    Location
    victorville,CA
    Posts
    172

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    yeah i'll second donsjave on this especially if the vin# calls for a 304,thats probably whats in it,like he said they MAY have installed a 360 if that was in the dealer inventory at the time,but usually warranty requirements would require like motor to replace one in vehicle.any "changes" would be highly unlikely.i would't put too much stock in DMV paperwork as to engine size as they have no way to verify size,and at one time someone could have stated the size upon transfer of vehicle which got entered in system.one way you could find out is to check cylinder volume with motor oil if you could find out how much volume is held in a 304 vs a 360 but in reality just wait intill the time comes to rebuild it then you'll know for sure

  2. #12

    Smile Ideas

    Quote Originally Posted by Linas
    Thanks for explanation. So now I can say it for sure - there are no numbers on any side of the block identifying the size of it. Therefore I assume that the engine was replaced, as you wrote. How to identify, what size is this Service replacement block? Were they always replaced with the same size, as the original block, which might have had a defect?
    The replacement blocks I would assume would be mostly all the same size. The stroke (or is it the bore) on a 304 is the same as the stroke on a 360 with only the bore being of a different size. What the dealer did was to order a replacement for the engine that failed warranty. I would suppose that a fairly large dealer could do his own work and the such. Send the engine out for proper machine work etc.
    So the short answer to your questions is that under normal situtions the dealer would install like engine with like engine (keeps the cost down that way). The only known way for you to id an engine definitley is measure with a micrometer the bore size and the stroke and this will give you the CI by doing some math.

  3. #13
    Join Date
    Feb 2006
    Location
    victorville,CA
    Posts
    172

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    found this on another site but it may or not be 100% correct.apparantly some 1970 360 motors were a thick wall casting and did not have numbers on the sides.i found this on AMC Hornet.com under AMC Myths at the bottom of the page.although it seems possible that some high performance blocks were made this way,you really got to measure the bore to find out.the difference between the standard 304 and 360 is the bore diameter.the stroke is the same

  4. #14
    Join Date
    Mar 2007
    Location
    Lithuania, Europe
    Posts
    17

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    Thanks! I will solve this puzzle, for sure.

  5. #15

    Default

    To expand on what others said, I found this:

    "Service Replacement" Multi-Displacement Block
    There was also a "Service Replacement" block made as a modified GEN-3 design. This is a 401 casting (same casting number) without the displacement cast into the side and with a 360 bore and thicker deck. In theory this single block could be built as any 343-401 GEN-2 or GEN-3 engine. A dealer could stock one or two blocks to use for warranty replacement. It was also sold as a heavy duty racing block, which is speculated to be the real reason it was produced in the first place. It appeared in 1970 in time for the 1971 Trans-Am racing season. Since it was a standard factory part it did not have to be homologated under T/A rules, and was not used in the 2501 "Mark Donohue" Javelins built to homolgate the "duck tail" spoiler.

    Found on the website:
    http://www.answers.com/topic/amc-v8-engine

    Though slim, its another possible explanation.

  6. #16
    Join Date
    Mar 2007
    Location
    Lithuania, Europe
    Posts
    17

    Default

    So going furthe with this issue - yesterday I had compression checked on my Javelin engine and it was about 10.0-10.2. The compression for 1973 304 engine, according to manual, should be around 8.4. So this engine most likely is not 304. Or can it be 304 with increased compression by the previous owner for the sake of higher performance?

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