Engine balance revisited

[Steve D.]

Please check my math. The density of steel is aprox. 490 pounds per cubic foot or 7.8 grams/cubic centimeter. I have several rods where the large end is about 15 grams heavier than the lightest one. To remove 15 grams from the big end of a rod (the rod cap boss), I have to remove aproximately 2 cc. of metal. One cc. is about the size of a sugar cube (.4 inch on a side). That seems like an awful lot of metal to grind off. Have I missed something? And for aluminum (2.7 gm/cc)pistons it seems worse.

Steve

[Joe L.]

Re: Engine balance revisited

Steve------

I think that your math is about right. However, I'll offer these three things:

1) It's often necessary to remove "more than a minor amount" of material from the balance pads on the big end of the rod to achieve proper engine balance;

2) You may have a "mismatched" set of rods; I would seek a set that have more consistent weights;

3) Notwithstanding the above, I wouldn't remove any weight from the big ends to weight-match the rods. I'd let the engine balance shop do all of the "weight-matching" and balancing. If they can't get a good balance with the rods you have, they'll let you know.

[Joe L.]

Re: Engine balance revisited

Steve------

I think that your math is about right. However, I'll offer these three things:

1) It's often necessary to remove "more than a minor amount" of material from the balance pads on the big end of the rod to achieve proper engine balance;

2) You may have a "mismatched" set of rods; I would seek a set that have more consistent weights;

3) Notwithstanding the above, I wouldn't remove any weight from the big ends to weight-match the rods. I'd let the engine balance shop do all of the "weight-matching" and balancing. If they can't get a good balance with the rods you have, they'll let you know.