Piston diameter

[FU64RY]

I have, from way back a complete set of Mopar piston rods and new bearings in a case..that look to have been reconditioned.
How do I tell what they are for or fit?
Pistons measure about 4.25" across.

 

[Lefty71]

There will be a different compression distance between 383 or 426 pistons... I would check that first.

 

[Nate S]

Compression distance. Take your calipers (or even a scale) and measure from the center of the pin to the top of the piston. If it’s a 4.25” bore you either have a 383 or a 426. I guess the other choice would be rod length. If they were together the short ones would be 383, long 426.

 

[4mulas]

Chev 427 and 454 also have that bore, but I guess you said you know they are on mopar rods for sure. So you can look up the rod part number and that will tell you or measure the rods. 383 rods are 6.358” long, 440 rods are 6.76” long.