Thread: Max Bore Of A 400 SBC

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Hello

I have heard that a 400 SBC will overheat if bored .060. I have also been told that a 400 SBC is thicker at .060 over than a 350 at .060 over. My question is can a 400 SBC be safely bored to .060 over for a race motor? Thanks

Slammer

I"ve wondered myself how far a 400sbc could be bored ,but I've never bored one past .030. You can have your block sonic tested and they can tell you exactly how much bore your particular block can stand.I just talked to a friend who has personally bored 3 blocks.060 without any heating problems,but for a race motor we both would perfer to stay a .030 or no more than .040. I suspect the siamese cylinders would be the problem area if there was a problem at .060