Thread: Chev Small blk 2 blt vs 4 blt

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Have two blocks. One is a 2 bolt and one is 4 blt 4.030
bore for a 383 build. Expect 500 + hp when finished.
Which blk would you use and what would the price differences
be between the 2 and 4 bolt main blk? Thanks

Which one is nicer to begin with? I'm meaning cylinder bores, cam journals, and main journals, straight decks, no rust etc? I've heard that a 2 bolt block with an aftermarket splayed 4 bolt main cap is stronger than a regular 4 bolt block. I've also ran more power through a 2 bolt block than some of the 4 bolt blocks I had. (Not that, that is a deciding factor) Those were early 010 blocks though. If one needs no machine work and one does, the one needing less money put into it may be the way to go. But in my mind the 4 bolt is cheap insurance. I guess I'm not much help.

Either block will be sent to machine shop for cam bearings, line bore etc. Using
Scat rotating assembly with all other goodies for the HP. Already have a 383
with 2 blt main (Splayed) in another car, but my thinking was since I have the
4 blt main blk why not use it. Just looking for opinions before heading to the
mch shop.

As Ryan said 2 or 4 as I have run lots of HP in both you just want every thing right at assembly. A 4 bolt sounds better but in your case or mine which ever is closest to the door when heading the machine shop is the one I'd load.

Most of the folks I knew growing up that had 4 bolt blocks never even turned them fast enough to need them.
How much racing are you going to do? Do you really see a need?
If the 2 bolt is in better shape... then I know where my monies would be going!

Its going into a 76 Camaro, but not for racing. Guess it will be
the 4 blt since its closer to the door, besides machine work to
splay a 2 blt isn't cheap. Thanks

My point was you'll probably never need any more than the 2 bolt, forget splayed / 4 bolt etc. if both blocks are equal, use the 4 just because. If the 2 bolt is in better shape - go with it.

When I was a teenager there were a lot of 283, 301, and 327 Chevys running around, turning 6500 - 7000 at the drag strip and none of us had ever heard of 4-bolt mains. However, the longer stroke and external balancing of a 383 will put more stress on the crank and main bearings. If you have both, I'd go with the 4-bolt.