Engine balancing

[xLibelle]

Anyone have experience in individual component weights, specifically checking for weight variations / "parts bin matching." aka, primary balance.

[mode]

Make sure everything weighs the same.

[strad]

I just read last week somewhere that conrods must not only weigh the same, but must have the same weight distribution as one another.

[mode]

That is true also. They must have the same weight distribution so when they swing through and around the crank, they don't generate harmonics.

[SpeedyWeber]

Factory engines have tolerences when the parts are cast. There can be a subtle difference in weight between parts and still be within tolerence limits. Machine shops will balance your internals to make them all the same weight and distribution of that weight.

I built a 306 Ford motor for one of my other projects and I had the motor balanced. The machine shop didn't just modify the parts to attain the same weight, they use the balancer and flywheel and spin the crank and rods to determine where any machining needs to be done.

Any motor I build in the future will go to the machine shop for balancing.