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

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: 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!). 

i believe it wasn't until the '60s that an acceptable cast iron crank
was even possible.  i'll bet gm's 'armasteel' first appears around
then.  i wouldn't be surprised if it didn't come down to a new process
for volume casting high-strength iron.

" 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. 

this makes a lot of sense.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen

adh@xxxxxxxxxxxxxxxxx                       and think what none thought