A few weeks ago, I had my newly rebuilt '66 motor fail about 30 minutes after firing it up. Upon inspection, there are 2 cracks in the #1 cylinder wall. I plan on having the walls thickness tested tomorrow. Can someone tell me the minimum acceptable wall thickness for a 289? The block was 40 over bored, so I know this was close. But nothing speaks like data.......I wish to be able to compare the actual measures to the recommended minumum thickness.