Has anyone heard of this. I have a chance to buy a 505 short block but the owner says that its a 4.25 stroke crank with stock six pack rods. All the kits I have seen are 7.1 rods with the 2.20 rod journal. Is this possible and it just has custom pistons in it or is this an older crank that I should stay away from. Any info would help. Thanks

Could be a custom piston... but 6 pac rods are HEAVY

I just thought it was an odd combo. Who even makes a 4.25 crank with stock 440 rod journals?

I would think you can get one that way... but most
turn them down to chevy so it ends up being cheaper
and lighter

1.82 CH, pretty long, heavy piston imo.

Old school style,fairly common with the longer Hemi rod. Not ideal today but back then parts choices were very limited.Worked OK but certainly not optimal now.I agree,good rod ratio but sluggo piston.

my aluminum 540 was 4.250 * 6.760 - diamond pistons...

Used to be great set up when Manley made the mopar length/width 2.20 BBC journal rod. (14279 if I remember right). 440 source was making a similar spec rod but not sure they do anymore. now nearly all BBM stroker cranks are BBC journal length to take chevy width rods as well as journal size. Both those rods were .990 pin, not the 1.09 Mopar BTW. This rod was also very popular for the 470 inch 3.90 stroke low deck.

Nothing wrong with a 6.76/4.25 stroke, my last 508 RB was that way and it was (and still is with a new owner) a torquey high revving Mutha Sluggo was DEFINATELY NOT a word anyone would use to describe it.

Six pack rod is not light but it's really no heavier than a lot of the aftermarket big block rods but it lacks the larger 7/16 bolts. If it's built right I wouldn't worry too much about it, as long as you're not putting 360cfm heads on it with a big cam where the torque peak is way up high it should be fine.