Not to sound stupid, but I always figured that the difference between, say, a "5.7 crank" and a "6.0 crank" was that the counterweights on the 6.0" crank were actually larger, as there'd be more room for counterweight under the piston and therefore you'd hopefully need to add less heavy metal. With the shorter rod, you'd be limited on how much room was available for the counterweight, and therefore may need to add more Mallory. I'm not sure if this is correct, though.

 

Eric,

You're explanation makes sense to me. But in speaking with Callies, they advised against running 5.7" rods with one of their "6.0 rod cranks" 1) for clearance issues between the counterweights and piston skirts and 2) for balancing reasons, since the thicker/heavier 5.7" rod piston will require more mallory.

Maybe the counterweights on "5.7 rod cranks" and "6 inch rod cranks" somehow weigh the same Along those lines, I've never noticed differences on "total weight" of a particular model crank - say a cast SCAT - based on what length rod it's set up for.

That said, at running it this way ("5.7 rod crank" with 6" rods) eliminates the need to cut down the counterweights if the next rebuild calls is a short rod motor.