Quote:

For the record: "Six Pack Rods" , ( part number 2951906, casting # 2951908 ) were not used only on 440-6 motors; in fact they were used from 1970 - 1975 on all forged crank HP motors and truck motors. The idea that these rods are found on only 440-6's is a common and pervasive urban myth.

I'm sure Chrysler marine used the HD truck stuff.

Another thought; these rods are indeed heavier than "LY" rods but they were introduced after unacceptable warranty claims arose from the '69 model year. Many experts have said that these rods are superior to the LY's despite the retention of the 5/16 rod bolts. In any case, I believe that a lighter reciprocating assy using hi quality rod bolts, 906 rods and modern lightweight forged pistons is actually a pretty stout setup. I'd much rather save weight on the (ridiculously heavy) stock TRW slugs than I would on the rods.

...of course these days, there are plenty of aftermarket rods that are both lighter AND stronger, but I still say the 906's get a bad rap that isn't particularly deserved.

Dave



So yet another reason for the performance drop after 69-70...???

I was always under the impression it was 72 and up, and not all 440's, just a random majority. I've seen more than one 71-4 steel crank 440's with an internal balancer. Wouldn't all the 6-pack rod 440's been external...???