Re: V8 Pistons

Posted by PackardV8 On 2008/8/25 21:33:54

Certainly spinning the crank for balance check is an optimal idea. Spin it at various rpm. But how far out is the factory balance anyway to require a spin test???

Anyone that has ANY 4 or more cylinder cranks laying around handy give it a try. Just set it on 2wo level knife edges. Use a smoothed top 2x4 will even work and test the BARE crank at various positions. It will stay where ever u put it.

If u really feel the need to ad bob weights that are all each the same weight then put them on too. It doesn't matter. The bob weights mean nothing since they are added at equal offsetting points across the crank throws. Kinda like adding a 1 oz. wheel weight to your car wheel and another 1 oz weight directly across from it. What's the point???

My guess is that the article that T'Pacman sited was for balancing TWO cylinder engines of certain varieties. The writer of the article probably balanced HD engines which has become nearly epidemic over the last 10 years. They are balanced at approximately 60% piston/rod weight with such bob weights as sited. BUT 2wo cylinder engines, especialy Twins are completely different engine. Note that the article makes no statement about rod caps or bearings. He's probably talking Twins which in most (but not all) cases have not such caps or bearing shells.