What does 400 crank mean as an automative term?

Question by Fdg: What does 400 crank mean as an automative term?
Here’s the context:

-You’re putting a small block 350 engine into your hot rod, right?

-Yes. 400 crank. 30 to a 383.

What do “400 crank” and “30 to a 383” mean here?

Best answer:

Answer by Geezer Geek
“30 to 383″ probably means they bored the cylinders of the 350 .030” larger, increasing the 350CI volume to 383CI. “Back in my day” they called this “I bored the cylinders 30 over”.

Not sure what they mean by a “400 crank”. “Back in my day”, we sought out “4-bolt mains” blocks (as opposed to the standard “2-bolt” mains) for high performance reworking.

ADD: Okay, I got it. A “400 crank” is a crankshaft pulled from a chevy 400CI smallblock, to replace the stabdard 350 crankshaft. The 400 just has a longer stroke then the 350 crankshaft: 3.75″ v. 3.48″.
This in itself will increase the CI displacement, but I’d have to “do the math” to figure out how much.
Increasing stroke also decreases low-end torque, so it has to be VERY carefully considered before going that route.

ADD2: Okay, I “did the math” just for kicks.

The overbored cylinders are 4.03 inches
The 400 crankshaft’s stroke is 3.75 inches.

so a 350 bored 30 over with a 3.75″ stroke yields 382.6666… CI, IOW, a 383.

And FWIW, just boring the 350 30 over only yields 5CI withouth changing the stroke, IOW, a 355.

Know better? Leave your own answer in the comments!