I'm in the process of gathering parts to build my own engine. I've rebuilt engines before and I feel confident, except that I do not know if it's necessary to balance the rotating assembly. Is it ok to just get the crank, rods and pistons and throw them on the engine an not worry about having them balanced? Many kits I see state whether they are balanced or not,

Any help is appreciated,

Jason

 

89,

The first step is to match the masses of the reciprocating parts - pistons, pins, rods and caps. A small balance and a die grinder work well for this, but be careful about removing mass. It's best to try to maintain an overall end-to-end mass ratio on the rods. A fixture can be purchased or made to check end mass.

Once component masses are relatively equal (within a gram) record the masses of the asseblies and report to your local speed shop with your crank and reciprocating parts. They'll be glad to take your money for matching the counterweights to the reciprocating parts.

If you are planning consistent operation in excess of 5,000 RPM, I would urge balancing the bottom end assembly. If you are only occasionally venturing into that area and only for short bursts, you might survive without a dynamic balance.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
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Thanks for the help Vader, you've helped me out many times before too.

So would you agree that it'd be ok to just use the parts "out of the box" if I'm not going to be spending much time above 5k RPM? Was the factory LO3 balanced by GM or did they just put the parts together?

Thanks again for always helping out,

Jason