402 bb engine
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Le Mans Master
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From: Richmond Kentucky
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402 bb engine
Can a 402 big block engine be bored .125 to create a 427?
Any cooling issues?
Any cooling issues?
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Le Mans Master
Joined: Oct 2007
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From: Richmond Kentucky
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Le Mans Master
Joined: Nov 2008
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From: columbus oh
that's an interesting # considering it was used as a 396 truck application and also the 402...it was bored to 4.125 to make the 402 and is the only block listed in ed staffels book that will take a .155 overbore safely (as long as there is no core shift) to make a 427.....so the answer is yes for that block only.....
Le Mans Master
Joined: Feb 2006
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From: "cutesy" TN
that's an interesting # considering it was used as a 396 truck application and also the 402...it was bored to 4.125 to make the 402 and is the only block listed in ed staffels book that will take a .155 overbore safely (as long as there is no core shift) to make a 427.....so the answer is yes for that block only.....
Le Mans Master
Joined: Nov 2008
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From: columbus oh
true but this block is specific to both bores with the identical part#....and i was too hasty to call it out alone, my bad...there are also three other #'s the same way but also #'s that are 402 exclusively.....i guess the point made was yes the 402 block he has can be a 427, but there are other 402 blocks that won't take the overbore..jmo.....
Le Mans Master
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From: "cutesy" TN
true but this block is specific to both bores with the identical part#....and i was too hasty to call it out alone, my bad...there are also three other #'s the same way but also #'s that are 402 exclusively.....i guess the point made was yes the 402 block he has can be a 427, but there are other 402 blocks that won't take the overbore..jmo.....
The only reason it is a 402 instead of a 396 is because in 1970 they lifted the 400 cubic inch rule.
GM did not make a new mold for the 402, they used the same one as the 396.
The "bean counters" were alive and well at that time. 
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Le Mans Master
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From: columbus oh
Can you do it? sure, but .125 over on a 396 is pushing the limits add another .030 and that is way too much IMHO.
The only reason it is a 402 instead of a 396 is because in 1970 they lifted the 400 cubic inch rule.
GM did not make a new mold for the 402, they used the same one as the 396. The "bean counters" were alive and well at that time.
The only reason it is a 402 instead of a 396 is because in 1970 they lifted the 400 cubic inch rule.
GM did not make a new mold for the 402, they used the same one as the 396.
The "bean counters" were alive and well at that time. 
Drifting
Joined: Oct 2008
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From: Rochester Hills Michigan
I was surprised to read this. Here's why:
I worked the summer of '69 at Tonawanda. I asked about the 402 and was told that it was an emissions engine like the 307 (283 bore, 327 stroke). It was to have a 4 inch stroke like the 454 and smaller than 396 bore. I calculate the bore would be 4 inches.
That makes a lot more sense to me than just bumping the bore 0.030, particularly when you figure they still called them SS396! That sure doesn't make sense.
Something must have happened to kill the 4 inch stroke 402 at the last minute...too far along to switch all the 402 paperwork back to 396? Cost, emissions weren't better, dunno. (It's also possible the engineer was messing with the new kid. I sure bought it, made perfect sense.)
I never ran across the 402 as a 0.030 over 396 before since it didn't come in the Corvette.
Bill
I worked the summer of '69 at Tonawanda. I asked about the 402 and was told that it was an emissions engine like the 307 (283 bore, 327 stroke). It was to have a 4 inch stroke like the 454 and smaller than 396 bore. I calculate the bore would be 4 inches.
That makes a lot more sense to me than just bumping the bore 0.030, particularly when you figure they still called them SS396! That sure doesn't make sense.
Something must have happened to kill the 4 inch stroke 402 at the last minute...too far along to switch all the 402 paperwork back to 396? Cost, emissions weren't better, dunno. (It's also possible the engineer was messing with the new kid. I sure bought it, made perfect sense.)
I never ran across the 402 as a 0.030 over 396 before since it didn't come in the Corvette.
Bill
