The factory bob weight of a "FACTORY" 455 piston/rod assembly are the same from motor to motor. My question arrises when going with an aftermarket forged piston. Is the bob weight more important to be consistant or more important to be exact to the OEM bob weight.

Another way to put it if all the OEM pistons/rods are 1 LB and the aftermarket piston/rods are 2 LB's will the balance be off ? Even though your maintaining consistancy.

You may ask why am i asking this.
I have a factory stock 455 that i am putting in 30 Over pistons into. The replacement pistons i have are from another build and are complete piston/rod assm. My thought was to if i was lucky to match the weight of the oem piston/rod assm. (If that was possible i think i am fine) but if i can't make the oem weight but made them all consistant weight will it be ok?

OK Professor what say he

 

Have it balanced. It's money well spent.

 

Balancing is cheap and the best thing you can do for the motor. While its apart and at the machine shop, have it done. You will be glad you did.

 

thanks guys i know that is really the right way to do it.
I don't know about cheap it's $350-$400 in my neck of the woods which is what i was trying to avaoid.

THANKS AGAIN for your responces

 

I think if you wanted to do it on tbe cheap you could weigh the old piston and rod assembly and compair it to the ones your putting in, just in my own experiment i found the speed-pro
L2323 040 were pretty close in weight to the regular deep dish cast pistons, I think if you could get the new set to weigh the same as the old set you be close enough to factory balance, but then you have to wonder how good factory balance is