273 crank in a 340
As correctly said, if you put the stock 340 pistons & rods on the 273 crank then you either have to drill out the end crankpins or add weight to the counterweights to get it to balance. Even this may not be perfect, as the minor counterweights on the 340 crank may be different a bit than on 273/318 cranks; I've never had them side by side to see. Edit: I am studying Max1196's pix right now; tnx!
Here is a pix of those holes. (These are actually on a SCAT stroker crank, but it is the same idea.):
![DSCN2498[1].JPG](https://www.forabodiesonly.com/mopar/attachments/dscn2498-1-jpg.1715249841/ "DSCN2498[1].JPG")
Correct. We have a 273 cast crank in my son's 340. As long as your 340's new bobweight is below the 273/318 bobweight of 2160-2170 grams, then the 273/318 crank's can be balanced by just removing weight. We used KB pistons and Scat rods, which dropped the bobweight over 400 grams from the stock 340's 2326 gr down to 1893 gr. Easy-peasy balance job.... simply remove weight. The shop took off 81-82 grams from each end counterweight for these pistons and rods..... about $100 for the work... cheap.
As correctly said, if you put the stock 340 pistons & rods on the 273 crank then you either have to drill out the end crankpins or add weight to the counterweights to get it to balance. Even this may not be perfect, as the minor counterweights on the 340 crank may be different a bit than on 273/318 cranks; I've never had them side by side to see. Edit: I am studying Max1196's pix right now; tnx!
Here is a pix of those holes. (These are actually on a SCAT stroker crank, but it is the same idea.):