few questions about 302 5.0 installation

[Jeff65]

Originally posted by David Fulford
One more thing I noticed, when I did my conversion, I was originally going to keep my T-10 transmission and re-build it. Because of the old style flywheel in the T-10, a 28.5oz harmonic balancer needed to be used. When I decided to go with the T-5, I had to use the 50oz harmonic balance. So from what I understand you have to match the harmonic balance to the flywheel, not the engine. If your using an old transmission with old flywheel, the engine probably needs to have the 28.5 oz harmonic balance. Maybe I was mis-informed but when I did my motor swap, this is what I was told. Good luck with it.

Its the crankshaft that needs external balance. Early 302s and 351's are 28 oz-in imbalance and late 302's are 50 oz-in imbalance. This applies to both the harmonic and flywheel. Note that in the '80's, an overlap occurs so for 80's engines you have to be sure of what you've got. Prior to '81 there's no question you have early engine with 28 oz-in imbalance. After '87 there's no question you have 50 oz-in imbalance. Its in between that causes all the confusion. The in-betweens depend on car model the engine was originally installed in, e.g. truck, LTD, Mustang, etc.

Regards your engine my guess is when you did the T5 swap you used the 50 oz-in flywheel from a late donor car. If you did this, certainly you'd need the 50 oz-in harmonic to offset it. Can't say this is right or wrong, just that its unusual and depends on who rebuilt and balanced your engine and what components were used.