I HAVE THE OPPORTUNITY TO BUY A FLATTY THAT WAS SUPPOSE TO HAVE A 427 CHEVY AND I RAN THE BLOCK ID # AND FOUND IT TO BE A 396. WHEN I APPROACHED THE OWNER HE SAID HE NEVER LOOKED UP BLOCK # AND SAID HE ORDERED RINGS FOR 4.25 INCH BORE AND ASSUMED IT WAS A 427. I HAVE HEARD THE BOAT RUN AND AM WAITING FOR THE OPPORTUNITY FOR A RIDE , MY QUESTION IS I HAVE NEVER HAD A MOTOR BORED PAST .060 THOUSANDTHS. IS THIS TO MUCH FOR AND ON THE THIN SIDE. THE BOAT IS GOING TO BE MY FAMILY FLATTY WITH MY OTHER FLATTY DOING THE FAST RUNS. LOOKING FOR THOUGHTS!
If it is a 396 I have only seen a few that have made the 4.250 bore and with concrete poured in them.My thought would be find a 427 or 454 block and take the guts out and change it.396/375hp blocks 4 bolt main were the worst about splitting cylinders also.
JUST READ IN MY CHEVY BIG BLOCK PARTS INTERCHANGE MANUAL IT ITS OK TO BORE TO 4.25 INCHES AS LONG AS YOU DON'T HAVE A CORE SHIFT. I WILL HAVE TO ASK IF IT WAS TESTED.
I have a friend who had a 396 bored to a 427. The motor went BANG in a huge way. I got to measure the cylinder wall parts after the explosion. The walls were only .060 thick in places. I would say no way.
I have news for you guys, in the old days the tough old early 2 bolt 396 block was coveted by Pro Stock racers as the only BBC that could be transformed into a 499CI screamer. This kept them under the 500CI limit. As mentioned already a block without core shift could be taken to the limits.
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