Hey guys,

We purchased the balanced 383 stroker kit from Eagle about a year and a half ago, and put together the engine approximately a year ago. Even since the new engine was put in, the car had vibrations which were especially strong at around 2000-2500 RPM but also exists throughout the RPM range.

The engine was put back together with the stock flywheel and harmonic balancer. We thought that the LT1 was internally balanced, and assumed that since the new kit was balanced as well, stock flywheel and balancer would work OK with the new rotating assembly. However, my research lately seems to be suggesting that LT1s are internally balanced at the front and balanced by a counter-weighted flywheel at the rear, meaning that the stock flywheel is not neutral balanced. If so, this would explain the vibrations...

My question is, for those who have built 383 strokers using balanced rotating assemblies:

- Did you have to use a new neutral balanced harmonic balancer and a new neutral balanced flywheel? Or did you use the stock flywheel and harmonic balancer? If neither, what was your solution?

Any help is appreciated, thanks in advance.

 

Stock balancer and had the flywheel nuetral balanced

 

I'm using a Fluiddampr and a neutral balanced rear flexplate (that used to be externally balanced but we knocked the weight off and re-balanced it)...

But you are right, LT1's are externally balanced when stock.... if you go to a balanced rotating assy you have to get rid of the counterweighted flexplate/flywheel and go to somethign that is neutral....

 

LT1's are both internal balanc in the front and external in the rear.
Reason for the LT1 cranks

Stock front balancer and a zero balance flexplate. There are a few of them on the market for about $30 - $100. Think mine was 39.99 and sold under the landcaster name and its SFI.

Now if you have a flywheel thats a lot more challanging. Its hard to find a zero balance 1pc seal flywheel.

 

Getting my shortblock from Chad this week. I have a mcleod street twin aluminum flywheel. It has a weight on it. Talked to chad, and he told me that the weight is to balance the stock crank. Now the new motor is internally balanced, he said to remove the weight, and still take the flywheel and make sure it is balanced. He said it would probably be out about 30 grams.

Sounds like you need to pull your flywheel and get it neutrally balanced!


Tim

 

I agree with everyone else in getting your flywheel neutrally balanced.

 

if you have an internal balanced engine you need and internal balanced flywheel, like the spec billet steel.

 

Thanks a lot guys; let's hope that there isn't too much damage to the bearings....

 

I'm going to throw this in since nobodys mentioned it. Did you get the internal balanced kit or external. Like if you bought the external kit it would be offbalance in the front since it requires a 400 balancer and stock Lt1 is neutral balanced damper. Figured I just mention it. Good luck.