Max overbore on a 396 block?
09-04-2015, 05:21 AM
#1
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Max overbore on a 396 block?
There is a consensus that the safe max overbore for a 396 cu in mk IV generation block is .060 !
My block casting no is 3969854 GM6 HI PERF PASS K20.
Do you know whether this can be sensibly bored further?? Thanks
My block casting no is 3969854 GM6 HI PERF PASS K20.
Do you know whether this can be sensibly bored further?? Thanks
09-04-2015, 08:19 AM
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09-04-2015, 11:19 AM
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09-04-2015, 04:44 PM
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396 Blocks
I have built many 396 NHRA/IHRA stock eliminator engines that make 580/590 horsepower. The only blocks that will live at +.060 over are the 65 962 casting and a few 961 castings. A sonic test is the only way to be sure. All of the +.060 67 and up blocks failed(split cylinders) above 550 horsepower. I think your block is a 68 or later block and will live at+.030 over. If you are looking for cubic inches, go with a 454 or a 496 rotating assembly. Good luck.
09-04-2015, 05:31 PM
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I have built many 396 NHRA/IHRA stock eliminator engines that make 580/590 horsepower. The only blocks that will live at +.060 over are the 65 962 casting and a few 961 castings. A sonic test is the only way to be sure. All of the +.060 67 and up blocks failed(split cylinders) above 550 horsepower. I think your block is a 68 or later block and will live at+.030 over. If you are looking for cubic inches, go with a 454 or a 496 rotating assembly. Good luck.
