[MikeK]

Here's a #4 that seized. I pulled this one from a 3000 mile engine a few years ago.

In this case the seized rings were the result of piston design. This import piston did not have a reduced land diameter and was intolerant to heat excursions that other pistons would survive.

There's always a lot of talk about #4 cylinder running hot, but one point is overlooked: If the cylinder (block) gets hot, the bore actually increases in size. For the piston to seize the piston itself must get proportionally hotter than normal. For this reason I believe it is not the direct result of the block around #4 running hotter.

Something is going on during the combustion process, specific to the rear cylinder, that causes overheated valves and a hot piston specific to the stock A engine.

High performance engines take advantage of resonance, the speed of pressure waves in air, to 'tune' intake and exhaust systems to enhance breathing at specific rpm's (frequency points) This can work against an engine, too.

In an 'A' there is an odd related phenomenon. The design of the split intake manifold and cumulative log-style exhaust in conjunction with the pressure wave pattern created by the firing order will cause the rear cylinder to run lean at specific rpm points. To my knowledge no one has ever explored this in depth. If #4 runs hot, it may very well be caused by too-lean running of that cylinder, not a water circulation problem.

I'd love to try changing the length of the two intake runner arms to an un-equal length, and baffling the #4 exhaust manifold port internally and see what happens on a test stand. Too many projects, too little time left.