my 340..3 cars, 34 years, 1 family. where to go from here

2 Darts said
If the head has all of that corrosion on one cylinder, why none on any of the others? Seems to me that maybe .060 is too far for that block. (Not used to seeing an LA block taken more than .040 over.) Suggest a Magnaflux of the cylinder in question. Otherwise, all the cams in the world won't make better power. 2¢

The 340 in my Duster is .060" over and has no issues, actually ran cold with a mechanical fan. I have heard of a couple going .080" over and still sonic testing just fine. They're the exception and not the rule, but .060" over should be fine unless thats a particularly poor example of a 340 block.

2 Darts said
I think I see your point. The likelihood that only one cylinder would have a valve open and three other cylinders with closed valves would be nil. There are 4 cylinders on the bank with valves at some point of activation, unless there are three cylinders in the "power" stroke at once. The more overlap the cam in the engine has, the more pronounced this should be. Not likely there would be just one cylinder with an open valve. This is what causes me to question the integrity of the water jacket around that particular cylinder.

I'd suspect a head gasket well before I suspected a water jacket on an engine that's only .060" over.

Plus, there's more at work than just open intake valves. And usually, it has to be an intake valve to get water into the engine unless the exhaust isn't hooked up. Intake runner design, single vs dual plane intake, how well the butterfly's in the carb fit, and even whether or not the car is sitting level all can play a role in water getting into one cylinder versus others. One flat tire on a car that's sitting will direct all the water to the cylinder with the open intake valve closest to that corner.