Hey Guys,

I am confused by some information someone told me today. I was told that big blocks should be externally balanced and not internally balanced. Is this true? When I built my engine I was told to have it internally balanced and include the 11inch flywheel with it so it all could be balanced.

Now I have vibration either in my flywheel or clutch. Not exactly sure which it is yet as I'm preparing to take it to the local trusted trans shop for them to have a look.

They have it wrong if possible internal balancing is prefered. Clutch and f/w can be balanced together make sure if eng is internaly balanced you do not use damper and f/w that are for ext balance applications. Having a wrong bolt for the PP can cause a vibration also. I put in a bolt for the cross member once same size different weight and had to pull it all out again.

454 uses a flywheel and front balancer that have some counterweight off center that is part of the balancing. 396 does not use this, i can't recal which way the 427 is. If you had the engine balanced its entirely possable but not likly that they compensated for that internally thus setting it up to use a balanced flywheel. Is this an automatic?
Another thing that can mess with balance is you can have a torque converter that is balanced dry but oil collects off center and shakes.

454's were ext balanced from the factory, and used a diff balancer and flywheel-they can be int. balanced, but need a bal. and flywheel for an int. bal. engine
396, 402, 427 were all int bal-you cant mis match the parts w/o rebalancing
if you rebalance a factory 454 crank to be int bal, it is usually expensive, as they use some pretty expensive heavy metal-most of the aftermarket 454 cranks will int bal ok

I am not sure if the flywheel was for an externally balanced engine or not. I used the one I got as part of a trade when I scored the Muncie trans. I figure at this point a trans shop or machine shop needs to take a closer look. If I were to purchase a brand new harmonic balancer and a flywheel for internal balance this possibly could fix the issue?

I do have plans to swap out the Muncie with a Tremec 6 speed in the spring. The added expense of buying the two new parts would not set me back. I just want the car to drive correctly and be fun again.



Bob

you need to find out from whoever rebuilt your engine if the crank was int balanced, go from there
if it was rebuilt using the factory crank, odds are its ext bal, but you have to know what was done to the crank, otherwise its a guess