Need help identifying this flywheel.

[88 Fox GT]

Back when I first did my 6 cylinder to V8 swap in my '65 coupe, I used a 1984 302 engine out of a Mercury which had TBI type of EFI on it (carbed afterwards). It was originally a 50oz balanced engine. I was told by a guy that said to make the 50oz engine work with a C4 tranny, I would need this special flywheel that he sold me. I'm pretty sure it's 28oz because I used a 28oz harmonic balancer and it worked fine. Is this thing really anything special or was he just feeding me full of ****?

How much would this thing be worth? I have no need for it anymore.

View attachment 461074

 

[88 Fox GT]

Someone's gotta know.

 

[D.Hearne]

A new 50 oz C-4 flexplate ( not a flywheel) sells for about $100 from B&M . You cannot balance a 50 oz 5.0 with a 28 oz damper and flexplate. It just doesn't work that way. And ditto for using a 50 oz flex and damper on a 28 oz balanced engine

 

[88 Fox GT]

A new 50 oz C-4 flexplate ( not a flywheel) sells for about $100 from B&M . You cannot balance a 50 oz 5.0 with a 28 oz damper and flexplate. It just doesn't work that way. And ditto for using a 50 oz flex and damper on a 28 oz balanced engine

Well I did it somehow. The engine originally had the big 50oz balancer and I used this flexplate and a smaller 28oz balancer and it ran fine.

 

[D.Hearne]

If it did, then it was a 28 oz balance engine to start with. There's a huge difference in the size of the counterweights on the crankshafts between the two. It is impossible to dynamically balance a 50 oz rotating assembly with a 28 oz flexplate/flywheel and harmonic balancer and vice-versa. If it was, then there would have been no need to market both.

 

[88 Fox GT]

The engine came out of a 1984 Mercury Grand Marquis. Would it have been 28oz balanced?

I do believe it had the large balancer, because I still have it in the garage. It is identical to the 5.0 balancer.

I guess I'm just trying to figure out exactly what went on when we put that engine in. I was only 14 then and didn't know much and that was 4 years ago.

 

[D.Hearne]

The engine came out of a 1984 Mercury Grand Marquis. Would it have been 28oz balanced?

I do believe it had the large balancer, because I still have it in the garage. It is identical to the 5.0 balancer.

I guess I'm just trying to figure out exactly what went on when we put that engine in. I was only 14 then and didn't know much and that was 4 years ago.

If it was the original engine, then it should have been a 50 oz motor. It could have been replaced by an earlier 302 though. The early 50 oz cranks weren't very good castings, I saw 2 that broke in half in stock applications, so it's possible that engine wasn't the car's first. The balancers look the same on the outside, but it's the size of the counterweight portion that makes the difference, ditto for the flywheel/flexplate.