[vettestr]

I used the copper head gaskets for years on blown engines because they were O-ringed and frequently taken apart. I would reuse the copper gaskets many times and they worked well from that application but also demanded higher maintenance or steps. Most of these engines were dry blocks but I have used copper with coolant in other applications too. You touched on one of my biggest gripes with copper and sealing of any coolant passage.

On an engine with coolant or a wet block with copper head gaskets chasing coolant leaks was just part of the joy of copper. Iron blocks with aluminum heads tend to scrub or work the gasket because of different expansion rates. Cometic gaskets don't need special sealers around coolant passages and they recommend no additional sealers at all be used. After a few heat cycles no leaks on my engines have shown up and they do not need to be re-torqued like copper. You can and I have re-used the Cometic gaskets with great results.

In terms of ideal piston to head clearance I like a minimum of .045" with steel rods anyway. I was trying to drop C/R without replacing the pistons so increased the piston to head as far as I could without trashing my valve train geometry. I was not deciding what parts to purchase but how far I could go or had too go so I could run pump gas on an existing engine.