Yes, heat for the exhaust manifold, but try not to locally get any area too hot as you can warp or crack the casting. To the extent that you can access the spaces, a needle gun will be helpful in the manifold, but I wouldn't try it on anything else. Ditto a carbide die grinder. Glass bead blasting is possible for the manifold, and for the disassembled head, but I wouldn't make sure to tape up the precision areas. For the piston tops, I don't know of anything beyond wire wheels and abrasive wheels, but, personally speaking, I hate to use abrasives on piston surfaces when the pistons are in the block. If it were me, I would get the heavy carbon off the piston surfaces, and call it good, knowing that working the generator hard in the future (100% loads) will burn them off, especially if you add some anti-carbon additives to the fuel. For small items, like valves, ultrasonic cleaning in a high pH bath may help, but I would first try to mechanically remove as much of the deposits as possible. FWIW: Some wire wheels are more aggressive than others, e.g. coarser, stiffer wire, and one can always sharpen the wire wheel on an abrasive stone. Personally, I try to sharpen the wire wheel in reverse compared to the direction thatI'm using it in, but either way works.
The solutions that I have worked with that can lift carbon are pretty darn corrosive, and I've never tried them on anything beyond borosilicate glass, stainless, and teflon. They are pretty hard on even straight glass. But I wouldn't claim to know all the de carbonizing solutions.
All the best,
2Pbfeet
