Got an older Brison 3.2 that has always been reliable and smooth running. It was recently involved in a crash. The carb was damaged and the timing linkage (mechanical advance) was bent and twisted. The crankshaft appears straight although it wasn't checked with a dial indicator. I installed a new WT 76A carb and gaskets and replaced the timing and throttle linkage. Checked and adjusted the timing as per manual at 28 degrees BFTDC at max throttle. The engine starts, idles and runs fantastic up until about 3/4 power/throttle. At about 6400/ 6500 rpm (Menz 22/8) it runs rough and misses slightly and sounds as if it is overheating even though it does this after a relatively short warmup of about 30 seconds (cowl on or off makes no difference). When I shut the engine down I notice the crankcase is EXTREMELY hot and takes forever to cool down. The muffler and cylinder cooling fins don't seem to be getting nearly as hot and cool down rather quickly. Brought the plane home and pulled the plug and turned it over by hand so see if I felt any resistance or roughness/grinding to see if the bearings had any obvious problems. It felt smooth and turns over freely. I have another Brison 3.2 (great running) and removed the plug to give it the same test for comparison and it felt identical. Been all over the needles and no amount of richening or leaning will alleviate the problem. Ignition battery checks out fine although I haven't tried bypassing the switch yet. Could the main crank/crankcase bearing be slipping/rotating in the case causing extreme crankcase heat? It appears fine by eyeballing it. Any ideas before I smash it to pieces?