General engine tech -- Drag Racing to Circle Track
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I have a 1968 307 block with casting number 3914638. It is a 307 for sure as bore measures 3.875". some sites say this casting is a 327 block and others say it is a 307. Is there a way to tell if there is enough wall thickness to bore to 4" without sonic checking? I have heard of some 307 blocks being able to be bored out to 4".