The cold water theory has been around forever and couldn't be more incorrect. True, all the 230 and 250 engines always seem to have excessive wear in the front cylinder. We raced them for 25+ years and have consulted with top GM engineers back in the 80's about this problem and what was told to us was this. It comes from a "green" cast block, coupled with the fact that the front cylinder inside the water jacket is machined for the water pump impeller causing the cylinder to "relax" or stress, and not stay round. This along with a short head bolt on the driver side deck, fails to correctly pull the cylinder round and hold tension as time passes. Its like when you only machine one side of a piece of steel and it curls like a banana, this is what happens to the cylinder when only the front face is machined for the impeller clearance, plus it is now much thinner than the rest of the cylinder in the front portion. After a block becomes seasoned and is rebuilt years later, it will not do this anymore, or at a minimum unless the front head bolt issue is resolved, and then all 6 cylinder will wear more evenly.
