I currently have a 90s block modified 351w with a c4 tranny, 302 flywheel. The 351 stock flywheel was to big so i just used the 302 flywheel and is nowshakes the carwhen in low rpms, and is now hitting the bellhousing. THis did not happenwhen I had the 302 engine in. Any idea on what it could be?

 

They are both supposed to be 50 oz right?

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did both engines use the same balance factor? ....Were they both late model engines or was one a 60ies engine?

 

I agree with the 2 other resposes, I belive you have the wrong balance flexplate in there. What year is the 351? Year of the 302 that the flexplate is from?

 

I thought you could use 302 flywheels with 351w, the 302 flyis internally balanced, and the 302 engine was a 68engine.

 

I think thats the problem child right there.

yeah you can use the 302 wheel on 351 as far as i know but thats not the issue.

The problem is(I THINK) the 68 engine uses a 28oz balance on the wheel and the other engine a 90ies you say...uses a 50oz balance on the flywheel/ flexplate.

I think you have the wrong balance factor on that engine.

-Gun

 

ok, so what is the problem 28 ounce /50 ounce or internal/ external balanced?

 

ok, so what is the problem 28 ounce /50 ounce or internal/ external balanced?

 

I cant say for sure I just dont know that much about all that stuff yet....But im betting if you take the two wheels and you look at the weight that is attached to them one weight will look about twice as heavy (a larger weight)

Im guessing your running a flex plate with a 28oz weight attached to it on an engine that needs a 50oz weight on the flexplate.

compare balance weight size of your 2 flywheels/flex plates or whatever I bet one looks much larger.

-Gun

 

The351W is for sure a 50 oz imbalance from the factory.... (they all were)

Early 302s were 28oz, later 302s were 50oz....

302s prior to 1985 use 28oz, 1985 and afteruse 50oz.

All stock SBFs are externally balanced.

This info applies to the harmonic balancer as well........