I'd like to start off and say this is such a great site it has been a such a help with this project. A little history.. About 2 months ago the infamous plastic timing gear finally gave up. Fearing that there was chunks of plastic in the bottom of the pan (which needed to be replaced anyways) I ended up pulling the 302 and np435 for a little r&r. After replacing a number of things and getting it all back together it fired up with little hesitation. Come to find out it's leaking oil out of the new front oil seal. I'm guessing it's because theres a groove wore on the old balancer. Now I have a new 28oz balancer from summit but it's snout seems shorter than the old one, which appears to be a 50oz. What even further confuses me is the old flywheel is a 28oz. My question is has Ford ever mismatched flywheel and balancers? I thought if you had a 28oz flywheel you would have a 28oz balancer not a 50oz. The truck year is an 81, had I known about the gray area here I would of looked for the crank numbers when I had the oil pan off to replace to the pump/pickup . Has anyone ever heard of such a thing? Or do you think some Jon Doe replaced the balancer at some point? The old flywheel is definately the factory one. Sorry for the lengthy post guys, any input is greatly appreciated.

 

It does sound as if the balancer has been replaced at some time.

This link might help - Ford Flywheels and Flexplates

1981 was the year that 302's were changed from the earlier 28oz inbalance, to 50oz

 

If it ran ok with the old balancer, and the old balancer looks good, just go to the store and get a sleeve for the old balancer. Some of them are called "speedi sleeves". This sleeve presses right over the worn area and gives you a new shiny surface for the seal to run. They work really good.