Buying a 383 kit here soon. If you take and balance an externally balanced kit, is it then internally balanced, and can thus use internal balanced flexplates and balancers?

Reason I ask is that I am getting a kit from a guy who bought a kit that was externally balanced, but ended up having the shop he bought it from balance it. So the kit has w/ it a 400 balancer and 168 tooth flexplate, but I was wondering if b/c it s balanced I could use my 350 balancer and 153 flexplate

Thanks

 

it could be balanced either way. you'd need more info from him or the shop as to what they actually did, or didn't do.

 

Sounds like he just took the rotating parts into the shop to make sure it is all properly balanced. "Production" balancing gets you in the ballpark, but part-to-part variation, between the rods, or between batches of pistons, for instance, means you are only in the ballpark. For insurance, you take the actual pieces you are putting together to the shop to have them precision balanced.

That's a fairly standard process, though, even for an externally balanced engine. If he had paid the bucks to make it internally balanced, I'm sure you would know it by the price he's asking.

 

The assembly is balanced to the dampener/flywheel combination. If it's been balanced for a 400 dampner/flywheel, that's what you use. Using a 350 dampener/flywheel would require rebalancing.

 

Yep just like rick said. If it has the 400 balancer and plate then it's probably been externally balanced for that. Which the shop add'd weights to the flexplate to get the crank balanced. To use a 350 dampner and plate it would have to be took back into the shop and rebalanced internally (crank drilled out) for this. Then you could slap a 350 dampner and plate on it.

 

I figured it was quite a bit more complicated to balance an external kit to be internally balanced. Thanks for the info guys. I am going to take it and get it checked by a local shop anyways to make sure it was balanced right. Plus I need to make sure it was all clearanced for the block!!!

Only reason I was asking is that I was worried about how well that 400 flexplate is going to fit into the 700r4 belhousing. I don't think it will be an issue, but has anyone had problems with that?

 

I've recently done searches and I found a post where a member used the bigger flexplate (400) with a 700-r4. But over all we're mostly 153 tooth people. Using a 400 type flexplate would more than likely require a different starter.

https://www.thirdgen.org/techbb2/sho...=400+flexplate