Re: RE:STROKER Engines

Correct. 390 and 401 blocks have heavier webs between the bores to strengthen the block. At least part of this was so that aftermarket four bolt main caps could be installed. I don't think the thicker webs are necessary for block strength itself. The thicker webs were added at least partially on the request of racers and the performance camp in the AMC engineering section. I've only tore down two or three 390/401 engines personally. I don't think there is anything else in the block above the others other than the thicker lower webs though. I'm sure Randy knows if there is, this is his area of expertise. 

Frank Swygert


On January 27, 2005  wrote:

> At least he didn't say they fit no problem. He misremembered the details as
> to which bearings are different, but I'd like to also point out the 401 (and
> I THINK 390) blocks were beefed up somewhat to account for the extra twist
> power of the longer strokes and larger bores. If this info isn't correct,
> now would be a good time to fix it!
> 
> 
> From: Guynn <amx69@xxxxxxxxxx>
> To: mail@xxxxxxxxxxxx
> Subject: RE:STROKER Engines
> 
> To whoever thinks that big AMC engines, like 390 & 401 have bigger main
> bearings than 290 thru 360 sized engines, you are WRONG. Every single
> AMC V8 crank used in every 290 thru 401 engine size uses the exact same
> main bearings. The only difference in any AMC crank is #1, materials,
> #2, stroke, # 3 rod journal size. All [not just some] 390 & 401 engines
> use bigger ROD journals. And all, [not just some] 390 & 401 has a Forged
> Crank. All small engines[not just some] built from 290 thru 360 size has
> a Cast Crank. All [not just some] have smaller 2.09 rod journals.
> 
> When folks pass around wrong info like swapping a 360 crank in a 304 for
> more cubes, or like stating a 390 crank is hard to put in a 304 block
> because the main bearings are a different size, all it does is show
> others you do not have a clue about AMC information. All that happens is
> you confuse others that do not know either. What folks are doing with
> this wrong info is repeating something someone else stated, not the real
> facts. This type of wrong info does no one any good. Please, if you are
> confused, go get a book and learn the facts before you attempt to advise
> others or else all you are doing is spreading false information. False
> information does not help anyone.
> 
> Regards,
> 
> 
> Randy Guynn
> 
> 
> .


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