Correct '69 427/400 Crankshaft

[Jim H.]

Hey group.
I'm trying to get a crank for my 427/400 block is this the correct casting number 3856223 for my block? From my sources this number references a 65-69 396. The 396 and 427 are pretty much the same except for the counter weight widths (427 are wider). Has anyone had experience with 427 cranks? If so may be send me a helpline. Good numbers for 427 cranks 66-69 (6223, 7115, 3904815, 3874874, 3804816).
Thanks,
Jim Hilton
43119

[Joe L.]

Re: Correct '69 427/400 Crankshaft

Hey group.
I'm trying to get a crank for my 427/400 block is this the correct casting number 3856223 for my block? From my sources this number references a 65-69 396. The 396 and 427 are pretty much the same except for the counter weight widths (427 are wider). Has anyone had experience with 427 cranks? If so may be send me a helpline. Good numbers for 427 cranks 66-69 (6223, 7115, 3904815, 3874874, 3804816).
Thanks,
Jim Hilton
43119

Jim-----


If by "correct number" you mean THE forging number that was originally installed in your engine, I don't think there's any way to know, for sure. As you have found, several different forging numbers were used. However, the GM #3956223 is a very commonly found forging for 427's and could very well have been used in your engine. Look for one that has 13/16" thick counterweights (except the #1 which is always thicker). I think that some of these forgings had the #3 counterweight machined thinner for 396/402 applications. However, even these can be used in a 427 by having the entire reciprocating assembly custom-balanced (which should ALWAYS be done anyway when assembling an engine).

It's very unlikely that a '7115' forging was used for your engine. This is an L-88/ZL-1 forging made from 5140 steel. Most other Mark IV crankshafts were 1053 steel.