ok im swapping in a 400 into my iroc, are all 400s externally balanced? if now how do i distinguish?

i have a early model flywheel that im trying to use, just want to make sure that all i need is the balancer plate to go behind it.

 

An engine building book I have isn't distinct but seems to infer the 400 is externally balanced unlike the 350

 

were all factory engines externally balanced?

im pretty sure ill need the balancer plate for the back of the flywheel, just wanting to make sure everythings gonna work together

 

All factory 400's were externally balanced using weights on the damper and flexplate/flywheel. You can use the weight plate with a neutrally-balanced flexplate, but you still have to use a weighted damper.

Or, you can have the crank internally balanced for many $'s. I believe you can also get an aftermarket internally balanced crank, although they tend to be one-piece rear main seal cranks.

 

ok im running a stick and i have a 2pc rear main flywheel from a 84 z.
will that work? they are neutrally balanced right?

 

An '84 flywheel will be neutrally-balanced. What I'm not clear about is whether that balancing weight tab thing works with a flywheel. I've only heard of it being for flexplates.

 

does anyone know if it will work, im sure someone on here has run a t5 with a 406?

 

If you can believe Summit Racing - High Performance Car and Truck Parts | 800-230-3030 , p/n SES-3-60-11-026:

"Counter Balance Plate, Steel, Use with Neutral Balance Flexplate/Flywheel, Chevy Small Block, 383 Stroker,Each"

 

$36.95 From Summit

$12.95 here:

Balancing Plate S/B & 454 B/B Chevy

and here:

Midwest Motorsports : Balance Plate - Use 350 Flywheel on 383/400 (Engine & Accessories - Accessories)