I am going to build a 383 package.Back in the day they were all external balance with the 400 bal. I notice that there are alot of internal balance kits now, is there a advantage to internal vs external??? thanks for the input.

 

External is more common and usually cheaper. Internal is arguably better. Either one works perfectly well, though.

 

Thanks . This will be a hot week end only car and external balance will save some coin.

 

The difference between external or internal balance crank is about the same as the cost of external balance damper and flexplate.

I'd go internal, personally.

 

For the average street engine, it doesn't really matter. With an internally balanced engine, you can tell people it's a 305 or 350 and they can't disprove you by looking at the dampener to see it's an externally balanced engine and probably a 383 or 400+.

When I built my 540, the forged crank was only available as internal balanced. Usually 454+ is always externally balanced. The added internal counterbalance does cause some problems when getting the rotating assembly balanced. It can block access to a counterweight if it needs to be drilled or if a slug needs to be installed.

I use a 396/427 neutral balanced harmonic dampener and flexplate. My SFI flexplate needs to be replaced every few years as per NHRA/IHRA rules. Because my rotating assembly has been balanced, it's easier to replace a neutrally balanced flexplate than it is an externally balanced flexplate and still keep roughly the same rotating assembly balance. Even a neutrally balanced flexplate isn't 100% balanced. Mine was off by 10 grams when spun up on the balance machine.

Rotating assembly balance and crankshaft balance isn't the same thing.