AMC V-8s

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(Identifying AMC engines and transmissions)
(a few tidbits to fill in missing information, deleted double information and innappropriate reference to Chevrolet small block V8 'Vortec' heads)
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==The Gen 3 V8==
 
==The Gen 3 V8==
AMC made some improvements in the Gen-2 design for 1970, thus becoming the Gen 3. This resulted in different block and head castings and slightly larger displacement. The only change to the block was adding approximately 1/16" to the deck height and increasing the stroke accordingly.
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AMC made some improvements in the '66-'69 Gen-2 design for 1970, thus becoming the Gen 3. This resulted in different block and head castings and slightly larger displacement. The only change to the block was adding approximately 1/16" to the deck height and increasing crankshaft stroke accordingly.
  
The Gen 1 to Gen 2 block deck height difference was 1/32" nominal, or 0.033". Gen 1 was 9.175" nominal block deck height and Gen 2 was 9.208" nominal block deck height per the Performance American Style booklet AMC printed in the early '70's.
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The Gen 2 to Gen 3 block deck height difference was 1/32" nominal, or 0.033". Gen 2 was 9.175" nominal block deck height and Gen 3 was 9.208" nominal block deck height according to the factory high performance modifications book named "''Performance American Style''" published some time in the early '70s by American Motors.
  
The 290 became a 304, 343 a 360, and the 390 a 401 (with a little added stroke in the crank than the 390). The 401 wasn't introduced until 1971. The 390 was kept for 1970 only by using a special piston; the pin height was altered to keep displacement at 390 inches. The head casting was changed to create a slightly larger "dog leg" exhaust port (Gen-2 heads have rectangular exhaust ports) to improve exhaust flow.  
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As a result, the short deck 290 became a 304, 343 a 360, and the 390 became a taller deck 401 CID engine. The 401 wasn't introduced until 1971. Using the new taller deck block, "AMX 390" engine displacement remained the same by using 'one year only' connecting rods and pistons. The head casting was revised to create a slightly larger "dog leg" exhaust port to improve exhaust flow.  
  
 
So there were four Gen-3 sizes:
 
So there were four Gen-3 sizes:
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*1971-'79 401
 
*1971-'79 401
  
The AMC V-8 finally went out of production when Chrysler halted Jeep Grand Wagoneer production at the end of the 1991 model year. This makes the 360 by far the most numerous AMC V-8. It can easily be built to produce over 400 hp on pump gas. It's as modern as any other make V-8 of the time, and has as much potential. There isn't as large a selection of performance parts, but the parts still available are the ones known to work well. The parts cost a little more than the more common small block Ford and Chevy parts, but no more than any other make. Cost to build is partially offset by the very good heads. Until the Vortec L31 5.7L head was introduced, Chevy heads weren't any better than AMC heads. Now, Edelbrock has aluminum heads for the 343, 360, 390 and 401 AMC engines.
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The AMC V-8 finally went out of production when Chrysler halted Jeep Grand Wagoneer production at the end of the 1991 model year. This makes the 360 by far the most numerous AMC V-8. It can easily be built to produce over 400 hp on pump gas. It's as modern as any other make V-8 of the time, and has as much potential. There isn't as large a selection of performance parts, but the parts still available are the ones known to work well. The parts cost a little more than the more common small block Ford and Chevy parts, but no more than any other make. Cost to build a higher performance custom engine is partially offset by the very good heads. Currently, Edelbrock and Indy Cylinder Head make aluminum heads for all 343-up CID '66-'91 AM V8 engines.
  
 
==Factory power ratings==
 
==Factory power ratings==

Revision as of 23:09, 3 January 2020

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