Re: AMC Pistons; Forged have downsides too , Cast has advantages ...

[farna@xxxxxxx]

Forged parts were used for durability back when they weren't that much more to produce than cast parts. That's why the old 195.6 uses a forged crank and rods. The GEN-1 V-8 is a bit different -- it uses a forged crank and rods also, but I suspect that's more because of the extremely short period from drawing board to production (18 months!). 

It takes a lot of testing to see if a cast crank will be strong enough. That's the reason forged crank and rods were used in the first 390. The SAE papers on the engine specifically state that there wasn't sufficient time for testing a cast crank. The 390 and 401 were produced in relatively small numbers when compared to the 304 and 360. My only conclusion can be that once the tooling for the forged parts were in place there wasn't enough volume to justify testing and new tooling for a cast version. 

Pistons have always been cast. Forged would make to much noise for a stock engine. 


On September 22, 2004 Bob Rapp wrote:

> The way I see it, there must've been valid reasoning behind AMC engineers'
> decisions to use forged cranks, rods, pistons, etc in their engine designs.
> Most likely for the same reason their blocks have high nickel content; it's
> all about durability.


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