I have a 383 2 piece RMS crank Im trying to sell, http://cgi.ebay.com/ebaymotors/Chevy...=p4506.c0.m245 thing is I have had it so long I cant remember if its an internal balance or external balanced crank. Is there any way to tell just by looking at it? I bought it through Checker about 8 years ago part # CS383 but when I try to pull that # its not found. I googled CS383 Crankshaft and got this
http://www.enginefactory.com/marine.htm

But Im pretty sure it wasnt an eagle crank.

Thanks

 

Look for "Mallory metal" plugs in the counterweights.

Most likely it's external balance.

 

Some of the internally balanced cranks for 6" rods don't use heavy metals, but it's probably not one of those.

 

Unless you know what you're looking for, you probably won't notice a difference without having one type beside another.

Mallory slugs won't create enough of an imbalance and they won't be in the proper location on the counterweights.

My 540 crank is internally balanced. There's an extra small counterweight at one end of the crank. It can cause problems when balancing the rotating assembly because balance shops would like to drill into the sides of the counterweights to add slugs. The internally balanced counterweight blocks one of the regular counterweights.

I would have to say since the one you're selling is cast, there's a very good probability it's externally balanced. I doubt they make a cast internally balanced crank for SBC or BBC.

 

Confession time - I didn't look at the listing.

I'd have to agree, being cast almost guarantees it isn't internally-balanced.

You could just say you don't know which it is, and the buyer is responsible for installation details.

 

Anyone who uses the crank needs to have it balanced with their reciprocating assembly anyway, so it's not going to matter all that much.

 

The only difference it makes is the balancer and flexplate/flywheel used. Internal or external balanced just means where reciprocating weight is positioned. Adding weight from rods, pistons etc needs balancing every time anyway.

The only good thing about an internally balanced stroker crank is that you can claim it's only a 350 and anyone checking the balancer to see if it's externally balanced to be a 383 or a 400 can't prove you wrong.