?? sixpack rod weights? and ly rod weights?

[sthorvictor75du]

hey guys, anyone know the actual weight of the six pack rods? also the weights of the ly rods? having one heck of a time tracking something solid down on google... also the weights of the factory low compression flat tops would help again.
I have a 440 with six pack rods and low compression flat tops, want to figure out what the weights of everything is so I can figure out something as far as rod replacement/pistons to up the compression without doing a major balance job. I know I may catch some heck from someone on here. however for some reason I thought you could play with the piston, ring, rod weights within 40-50% of the total mass of whats already in there as long as each set is weight matched to eachother..? without touching the crank..
thanks again

 

[oldkimmer]

.........Its always best to balance.......6 pac rods r very heavy......use a new rod with the piston of ur choice.........kim..........

 

[pishta]

Youll have to weigh rod at both ends. Not the entire rod at once. Different centripetal masses...or something like that. You can get very close on stock rod balance by equalizing all caps, then equalizing all rods, so all weigh the same in total end to end. there are jigs that do this on a scale or you can balance the rod on a knife edge at the seam and weight the little end and equalize.

 

[roccodart440]

.........Its always best to balance.......6 pac rods r very heavy......use a new rod with the piston of ur choice.........kim..........

yup.

I beam polished and shot peened my Ly's and used KB Hyperutechtics (spelling?) in my last 440 and they still needed mallory metal to balance the thing. Given 6 pack rods are heavier i'd avoid them.

 

[moper]

There are two parts to balancing. The first part is equalizing the weights of the set of pistons and pins, and then the big and small ends of the rods. Not total weight - only each end. Once that's done you take those figures and get your "bobweight". That's the weight that is clamped to the crank to simulate the two different systems: the reciprocating mass (pistons, pins, rings, and small end of rods), and the rotating mass (the crank throw, bearing, oil, snd big end of rods).
The second part is the weights are attached to the crank and it's spun. A computer figures the imbalance and the crank counterweights are either drilled to remove weight, or drilled and Mallory metal is pressed into the hole and then welded to add weight. Then the crank w/bobweights are spun again and if more weight needs to be adjusted that's done until it's balanced.
So - applying that to your engine - factory cast pistons are heavy - they have steel expansion limiters and big pins... Plsu - the six pac rods have the thicker beams and heavier big ends. So by running them you run the risk of having to add Mallory. If it's a forged crank engine you can use the six pac rods but to internally balance (to run any harmonic dampener rather than the special 6bbl one) you will have to add weight. If you want to make it cheaper - run the LY rod with a stock piston, or preferrably the LY rod with a hyper piston. then if anything the crank will only need to be drilled and be able to run any dampener.
You cannot change rods or pistons to different models (even stock types) than what you have and not have to re-balance.

 

[RustyRatRod]

The six pack rods are not that big of a deal. I kinda like um myself. If you run a modern, light weight piston, you end up just as light or even a touch lighter than a stock LY rod with a stock type piston. The difference isn't really as staggering as everyone makes it out.....although the six pack rods are certainly heavier.

This has been argued back and forth in the ground. Here's how I like to put it. You'll never feel the difference in how the engine runs with six pack or stock rods. If you think the six pack rods hold a car back, you've never seen a box stock A12 car blowin the doors off the competition. Nuff said.