Using 6pk rods with a forged crank?

[Commandough]

So I have been researching this and wanted to get some info before I make any choices and waste my time and money. I have my eye on a set of 6pk rods and 1 forged and 1 cast crank. Would prefer using the forged crank but see that these 1970-72 rods require external balancing. Is there any way to use the forged crank with these rods? Please don't turn this into a debate on the rods or the cranks. Just need to know if I can use the forged crank with the 6pk rods or not. What mods or machining can be done. Building for a 68 Sport Fury 4 speed. As always, appreciate the help.

 

[70NEWYORKER]

I'm 95% sure on the following info : Sixpak rods were used with forged cranks in 70-71. The extra weight of the rod is what necessitated externally balancing the engine. Find the right damper and recipe for converter weights locations. Then take everything to a machine shop and get it balanced!!!!!!!!!!!!!!

 

[Big_John]

The six pack rods are more trouble than they are worth.

IMHO, they are way too heavy, but to use them, you would need the correct damper and have to add converter weights or use one of those cut up aftermarket flexplates. Internally balancing is $$$$ because they have to add tungsten weight slugs to the crankshaft.

FWIW, every 440 that I've encountered with a rod failure had a large "sixpack" rod in it.

For your use, they will do absolutely nothing except empty your wallet. I would pass them up and buy some new rods if you feel the need.

 

[Davea Lux]

A number of companies sell aftermarket rods that are the same weight as the stock rods but that are considerably stronger in the 6.76" length. These are a better choice than the six-pack rods and already have the 7/16" high tensile bolts. See item #200-1132 at the 440 source. -440 Source
This avoids the whole problem of having to do extensive re-balancing.

Dave

 

[commando1]

Just say NO to 6 pack rods. Too damn heavy. Modern rods are lighter and stronger.

 

[Commandough]

I just about bought them last night. Price seemed good but sounds like a mess to make them work. I'll just save my pennies and pony up for some nice H Beam rods. I've even heard the LY rods are up to the challenge if under 600HP. Very glad I asked.

 

[CBODY67]

I'll concur on the weight issue! Get some good aftermarket steel rods, some lighter-weight pistons and piston pins, knife-edge the crank counterweights, and I'll suspect MORE horses will get the flywheel AND it'll zing-up quicker than what you're used to. Of course, it'll need a good balance job, too.

CBODY67