Inliners International Forums General Discussion Engines Basic GM crankshaft question?

Why are the main crankshaft journals in the Chevy Inlines (and lots of other GM cars of 1940's -50's) different sizes?
I see lots of other makes with the same diameter of standard crankshaft on all the mains.
Example: 1954 Chev Truck engine has 4 mains, (FM) 2.6855,(FI) 2.7155,(RI) 2.7465, (R) 2.7775
{each is about .031" bigger than the previous}
Anybody know why?

Tweaker,
If you think about it, it really makes sense to increase the main bearing diameter, (hence, the torque capacity) as you progress from the front cylinders to the rear ones. Each main bearing journal has to transmit the accumulated torque from the cylinders in front of it, through to the rear of the crankshaft. As you progress towards the output end of the crank, (flywheel end), more torque has been created, thus the need for a stronger shaft. Back when these engines were designed, such good, conservative, engineering practices were considered quite normal.

Today - engineering practice must satisfy the economics as well and stepped bearing journals cost way too much in tooling. Finite Element Analysis done up front makes sure the bearings are not only sized to accomodate bearing loads, but torque transmission, deflection, heat transfer, etc.