Harsh Vibrations!

[phazersonstun]

So I dropped in an 1988 roller-cam 5.0 into a 67 coupe. The car is pretty much together but I get a NASTY vibration when I rev it. I Know that the original 289 was internally balanced while the late-model engine is externally balanced. I had to use the old flywheel from the 289 because the 51oz for the 5.0 was too large for the C4 transmission's bellhousing. Is this my problem or is it something else? Any help would be greatly appreciated.

 

[bnickel]

So I dropped in an 1988 roller-cam 5.0 into a 67 coupe. The car is pretty much together but I get a NASTY vibration when I rev it. I Know that the original 289 was internally balanced while the late-model engine is externally balanced. I had to use the old flywheel from the 289 because the 51oz for the 5.0 was too large for the C4 transmission's bellhousing. Is this my problem or is it something else? Any help would be greatly appreciated.

that is most definitely your problem. the balance factor for the 2 engines is so much different that it is causing the engine to basically fight itself on every turn of the crank. you need a flexplate for an 81 or 82 302 with the small bell c4.

 

[C0V3R]

btw its 50oz not 51oz

 

[bnickel]

btw its 50oz not 51oz

true, i didn't really feel like pointing that out though.

 

[phazersonstun]

Really? Great! So where can I find one? I haven't seen an such an early V8 at the junkyard in a long time. Could I find a flywheel from a similar platform?

50oz. Got it.

 

[rbohm]

here are 4 such flexplates from summit racing;

http://store.summitracing.com/egnse...94905612+4294863728+4294840126+115+4294871826

 

[BornInAFord]

You can also have a machine shop rebalance your current flexplate to 50oz, too, although this may be as expensive as just getting a new correct one or finding one on ebay. You definitely DO NOT want to run the car as you currently have it as it will tear itself apart in quick order.

BTW, all factory 260, 289, 302, 5.0L and 351W engines were externally balanced. The difference is in the balance weight on the flywheel/flexplate and front harmonic balancer.

 

[CraigMBA]

And while you're at it, what damper did you use?

 

[phazersonstun]

I am using the stock 5.0 dampner. Why do you ask?

 

[Pbum5]

Because - You need the correct balance dampener and flywheel/flex plate for your application.

 

[CraigMBA]

I am using the stock 5.0 dampner. Why do you ask?

Because that one's 50 oz and OK and the other one is 28 oz and isn't OK.

 

[bnickel]

the 5.0 balancer is also balanced for the 50oz imbalance of the 5.0 motor as well as the flexplate. same goes for the early 28oz motors, the balancers and flexplates must match there as well.

 

[phazersonstun]

Right.