"Is this high compression due to carboning of the heads..? I thought nominal pressure values were around 165 ... then again, I am going from memory and this may also be for a turbo."

I would have to agree with you on that. I have seen a boat load of red engines that only spun up around 150-170 PSI and if I saw anything over 190 I would suspect excessive carbon in the combustion chamber. It does not take a great deal of carbon to elevate the numbers and every head I have pulled had at least .015-.030" of carbon evenly coating everything. It was not too long ago I had a car come through that failed smog due to excessive Nox and it wasn't by just a little bit either, that sucker was pumping it out. We went through the basics and made sure everything was dead nuts and it was all on the money. It was however pumping out 200+ PSI and it had 200K+ on it. Unfortunately the old timer was not willing to spend the money necessary to diagnose it thoroughly so he went on down the road without fixing it.

On a fresh rebuild I would expect to see numbers in the 180-185 range. Mind you that is on a compression test done by the book, warm engine, throttle blocked,open ALL plugs removed, 4 revolutions per cylinder.

Mark