Re: [AMC-list] 401 Crank into a 343 how to sought

[Frank Swygert <farna@xxxxxxx>]

1. As stated, GEN-2 (66-69 290/343/390) and GEN-3 (70+ 304/360/401 and a 
special piston for 1970 only 390) AMC V-8s all use the same bell housing 
bolt pattern. Crank flange is different for pre 72 and 72+ -- 
Borg-Warner or Chrysler automatics. I believe the stick shift flywheels 
interchange, may require a little machine work on a 72+ to fit a flat 
flanged 66-69, not sure. Bolt pattern is the same, but the 72+ crank has 
a raised center to fit the Chrysler style automatic flexplate.
2. When mixing cranks the engine MUST be balanced. The factory balance 
is close enough for a rotating assembly made up of all matching factory 
parts, but you aren't using 401 pistons and rods with the 401 crank 
(block is irrelevant since it doesn't move). So I wouldn't worry about 
getting a 401 flywheel or flexplate. The 360 flywheel/flexplate can be 
used and then all the rotating assembly must be balanced together. Those 
parts will then only be good for that engine, but that's the way 
something like this has to be done. If lighter (or heavier) than stock 
aftermarket rods are used the whole rotating assembly needs to be 
balanced anyway.
--
Frank Swygert
Publisher, "American Motors Cars"
Magazine (AMC)
For all AMC enthusiasts
http://www.amc-mag.com
(free download available!)

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