Because harmonics are little demons from the ether that math has yet to explain... I have a ten spline three speed, but I do not have the output yoke for it. But I have a bellhousing for a 390 that would go with it, and into something else someday.
Because the cranks actually have an imbalance and that is why the external balance occurs with the Dampers and flywheel/flexplate. The crank is designed to be used with either the 28 oz. or the 50 oz. and if you change them, even in pairs, it will spell DISASTER.
Yessir...you WILL know. A friend bought a late 302 powered Fairlane at a show we were at, and it had the early balancer on it ( 28 oz. ) It was VERY evident. It DID run for a while, however, and we swapped it once he took posession of it, and never had anything happen afterward. Also, SlowandLow, I remember the same thing you stated in regard to the flexplates...I seem to remeber the always 351W having 164 T flexplate.
The crankshaft was changed. If you put an early 302 crank next to a late 302 crank, you can see it visibly. The change in the counterweights on the crank necessitated the change in the external balance factor. If you put 28oz balancer/flywheel on a 50oz crank (or vice verse), you will have vibes and you will probably break the crank...
I have a 1981 (03-11-81) 302 with a 2MAE crank, which is a 50 Oz crank. So much for the 82 and later 50 oz.
The Jalopy Journal
