Re: [Amc-list] AMC Block Sizes

[David Crooks <david.crooks@xxxxxxxxxxxx>]

> I seem to recall seeing on one of the AMC sites that all the V8 engines, 304 - 401, 
> were made from the same block. So there is no "big block / small block" with AMC's. 
> Did I read that correctly, and if so, how does that work with such a large 
> displacement difference?

Hi Neil,

This is almost, correct...  All AMC V8's have the same external dimensions, but there
are internal differences, so you can't quite say they're made from the same block.  
There are differences in the cylinder castings, and bearing support webbings.  The 
290/304/343/360 blocks are essentially the same internally (with the 304/360 having 
a higher deck height to allow for the longer stroke.  Similarly the 390 and 401 are 
essentially the same internally.  

However from the outside, they're exactly the same, so a 401 will bolt up where a 
304 once stood, or vice versa.  

The way it works is with changes in stroke!  To get a bigger displacement, you only 
need a longer stroke!  If you have the luxury of enough sales, you can afford to make 
two blocks.  If you don't, you stroke what you've got!  The catch is, you're limited in
how far you can increase the stroke of a motor.  I've seen AMC's pushed to ~427, but 
that's about the limit.  It's also starting to lose performance, as the stroke is getting
too long.  

Cheers,
Dave

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