robcas47

iTrader: (2)

can a 400 crank be dropped in a 327? if so what else needs to be done and what is the new ci for the engine?

1994Z28Lt1

iTrader: (1)

depends on what year 327 it is, the earlier 327's were small journal and the later 68+ i believe are large journal 327's

check the casting number on the back driver's side of the block if it says 3970010 your in good shape

the 350 was produced using the same block casting as the later (large journal) 327 so dropping a 400 crank in there (with probably some machining)

whether its a 327 block or a 350 block if you punch it .030 over you will end up at 383 CI

robcas47

iTrader: (2)

the engine is out of a 66 Impala, i believe it to be a small journal since as far as i can remember the casting number is 3858180 and is also a 2 bolt. i thought .030 over only gave you a 355. are you talking about with the 400 crank and a .030 to end up with a 383?

cnorton

iTrader: (1)

Mortec.com lists the following for that casting number: "3858180....327...64-67...2" with the "2" denoting two-bolt mains. That is most certainly a "small journal" block that would require opening up the main sizes to accommodate a 400 crank. I've never attempted it so I don't know if you'd be into dangerous territory with that much material removed from the main webs. I do know that large journal 327 (same as 350) blocks have more meat in that area while some numbers (such as 3959512) are sometimes found to have small or large journals.

If it were my project, I'd pass on the 400 crank approach.

Good luck.

c

Awesomeperfmachine

The correct solution would be to have the crank's main journals ground to the size needed rather than trying to line bore the block oversize.

To clarify some things:

Chevrolet smallblocks had 3 different main bearing sizes:
400 block - 2.650" diameter
350 and Lrg Journal 327 - 2.450" diameter
Sml journal 327 - 2.300" diameter

So to fit a factory 400 crank into your block, you would need to have the machine shop grind the mains to the diameter of the block you have. This will be required no matter which block, small or large journal, you have.

The aftermarket "383" cranks you see advertised for a 350 block, such as those from Scat, Eagle, etc will have a 2.450" main and therefore are a drop in for a 350 or Lrg Journal 327. Typically it is cheaper or just as cheap to buy one of these new cast steel aftermarket cranks than to pay to have a 400 crank turned and polished. However if your block is indeed Sm journal you would still have to pay to have the mains turned down even on the new crank.....

Also, 327 & 350 blocks are both 4.000 bore. So 4.030 bore x 3.75 stroke(400 crank) would yeild 383 cubic inches.

Hope this helps