4-bolt mains in SB?

What year did GM begin using 4-Bolt mains in 327ci in stock/production Corvettes?

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IIRC the first 4 bolt SB Chevrolet V8 was the 1968/9 Camaro 302. All mid year 327 Corvette blocks 3782870/3858180/3858174/3892657 were 2 bolt mains up to and including 375 HP. The Corvette 350 in 1969 block number 3970010 was the first 4bolt with a rare few having 2 bolt. That same block was a 2 bolt main 327 in 1968 but not used in a Corvette, The block used for the 302 Camaro was used with 2 bolt mains in 1968 Corvettes. Only one place have I seen it said that a 4 bolt 327 existed and that is block number 3956618 which does not show as a Corvette 327 block in the Black Book (?).
Simple answer is your '63 is a 2 bolt.
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Dad
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Thanx for the info, Dad. I knew mine was a 2-bolt main when I stripped the block before taking it to the machine shop to be worked over. I was just curious if the mains had ever became a point of failure when they increased the HP in the C2- lib

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Very defiantly was a weak point of the small block and journal size was later increased to stop some of the failures. The quick winding engine was known for "spinning the mains". It started out life with a 2.30 diameter main, moving up to 2.45 in '68, (302 induced) and finally 2.65 in '70. Under hard acceleration the design allowed the crank to push against one side of the bearing wiping it clean of any lubricant and pulling the bearing loose and spinning it with the now scored race. Lots of odd shaped parts soon followed.
Dad 05 C6 Silver/Red 6spd Z51 72 Shark Black/Black/4spd 64 Red/red/white top/4spd
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I don't think there was ever a 4 bolt 327 was there?
Dad wrote:

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Ric Seyler
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On Wed, 25 Apr 2007 10:44:13 -0500, Ric Seyler
This site alludes to the idea that it's possible:
http://www.auto-ware.com/techref/CHV_BLK.html
See #3956618

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While it is possible, it didn't happen. That block was only used as a 4 bolt in a 302, I'm pretty sure. I believe it had a problem with a 4 bolt main and was why the 0010 block came out and basically replaced it.
From the Mortec site: http://www.mortec.com/castnum.htm
3956618....302.....69....4...Z-28 Camaro 3956618....327...68-69...2 3956618....350.....69....2 or 4 3956632....307.....69....2 3959512....327...62-67...2...Was also used for some "CE" replacement blocks 3959532....283...64......2...Used for some "CE" replacement blocks 3959538....327...........2...Chevy II recessed oil filter boss, Used for some Chevy II "CE" replacement blocks 3970010....302.....69....4...Z-28 Camaro 3970010....327.....69....2...Trucks and industrial 3970010....350...69-80...2 or 4
While the 327 was built in both small- and large-journal sizes, I don't believe there have ever been a 4 bolt version from the factory, with the possible exception of rare heavy duty truck versions such as the little White single axle tractors. Since they were a heavy duty application, they _MAY_ have had a 4 bolt main but I don't know.
Now on that point, there is nothing to prevent taking a 4 bolt LJ block and dropping a LJ 327 crank into it with proper pistons and creating a 4 bolt 327 that would look completely factory. The only issue is I don't know of a steel forged LJ 327 crank, only cast LJ 327 cranks.

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puked:

And that would be a beautiful thing... -- lab~rat >:-) Do you want polite or do you want sincere?
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lab~rat >:-) wrote: The Chevy V8 Engine Casting book doesn't list a 4 bolt main 327.

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Eugene Blanchard
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