Does anyone know the bob weight of a 1973-1974 six pack rods 440 crank ? i have heard it is around 2700-2900 grams in stock form, i know this question has been asked before but i can't remember the ad. thanks to all,,,,,,,,, only check one time a day.

The rotating assembly in those engines is heavy. Heavy rods, heavy pistons, heavy pins, heavy rings, etc. Bobweight is often over 3000 grams. They rev like a tractor!

I was thinking it was in the heavy range, i have a NEW eagle crank , but it is #2550 grams, i can use it but i don't want to pay $1,000 to 1,250 for pistons ..........that is too much for a street car......lol.

2550 Is well below the bobweight for a heavy rod set up. Ain't no marrying them together without mallory.
2900 sound about right from memory. I could check but I don't know if I have any pistons around.
What the heck piston are you looking at for that kind of money?

Thank you for looking, diamonds are $1,350 now , looking for a dome piston running a #88cc head, i can get a speed-pro dome but looking for a lighter set, where i live...... it is tuff to get anything done, machine work is the main thing,...................about ready to go to a stock steel crank. some pistons are 9.7 comp that does not do a thing for me. lol

Check ross,srp, or icon.

Icon/srp/wiseco/ diamond /ross ..................... I have checked and #1 are cheap heavy dome speed-pro all are flat tops, with no comp # numbers with a #88cc head , but the pricey dome pistons, my luck ,...... if anyone has a solution ( piston wise) please pm me,............

What about getting a lighter set of of H beam rods , the stock 6pak rods were a bad idea , hemi sized rods with little LY rod bolts. Also cut the heads down to a smaller chamber ?

I cut #100 thousand off the # 452 heads on another motor , that many be a route for me, i checked on rods Thursday and they are 809 grams for a steel one, don't know how much six-pack rods weight ,.......... since you can't get what you want you have too compromise , sounds like life !! lol

one random six pac rod
926gr
656 big
270 little

Now that is CRAZY ! but they work ,........thanks for the info,......................LOL

My friend bought a 66 Satellite racear. It ran decent. Decided to lash the valves. It had stamped steel rockers. So obviously a hydraulic cam. It also has a 6 pac balancer. Hew was told TRW /Speedpro type piston. Wiyh that balancer it has to have 6 pac rods as well. So it's all old school and heavy. Easily runs 11.40s and has dipped into the 11.30s. He runs it to about 6300. For the street I wouldn't worry about bob weight being heavy if you have the parts already.
Doug

I'm not knocking them. I just didn't think they would work with 2550.

You would need a piston/pin in the 790gr area. The stock piston/pin is somewhere in the 1000gr area as I can remember. I don't have a piston to weigh though.

You are correct , trw replacement pistons are 1000-1100 grams , piston/pin

I have a stock piston I’ll weigh. I know the pin is bigger and heavier than a stock one. I also have a 74 motor home 440 (never apart) that has 6pac rods, flat tops, steel crank and a regular balancer.

Do you guys think that if i buy a set of LIGHT Wiseco dome pistons /new crank bob weight (# 2550) / LY 440 rod in a +30 over block will it work in a street car with no balancing issues ? thanks for the input !!

Random ly rod
607gr big
239gr little



Stock bearing 58gr one set
rings 1/16-3/16th 62gr.

looks like you would need a piston/pin in the 916gr range.

looks like a ross 80762 with a standard pin (225g) would be real close.

On their website they list the pin as 158 but that has to be a typo, only the .990's are that light.

If that eagle crank is new and has never been balanced its probably not 2550 exactly or at the right place. There is a difference between "target bobweight 2550" and balanced to 2550.

Thanks I see your point, i got a card with the eagle crank with the weight, ???? you are right hoo know's ...................a bunch of trouble. with parts ! ............LOL