Can carbon buildup on psitons/heads increase compression?
 

I'm starting to research an engine rebuild. I hear that tiny variances in head/piston clearance will change compression, from say 9.3 to 1 on my SC engine to 9.8 to 1 (Euro spec). I've heard we're talking about a distance on the order of magnitude of a gasket. Maybe .5mm or so is all it takes. True?

If so, I'm guessing there's at least a few hundred microns of carbon between my heads and pistons.

It would seem that if compression can be changed by such small distances between head/piston, carbon buildup would have an effect on compression over time. Anyone heard of compression increasing over time as a result of this buildup?

Just curious.

Absolutely - That's why some older engines "diesel" and continue to run after they are shut off. The heat and compression causes pre-ignition. Was a bigger problem in the older days with poor fuel, weak spark and engines that burned more oil.

Like Bob says, the short answer is "yes."