[classicauto]

Reason I asked is typically, knock in a rotary isn't heard for long. USUSALLY its not even audible before its blown. I've only ever once heard the death rattle for about 0.5 seconds in all the engines I've blown.

My other point was the need for richer mixtures in vaccum would indicate you've disturbed the efficiency of the combustion chamber. If you're having to run closer to stoich, or under it, to achieve proper power/good running then it means the combustion chamber isn't "mixing" the air and fuel as effciently as it was which would cause the need for more fuel to be present for an even burn (good running) when the spark lights off.

Whether it is the polishing, runner smoothing or otherwise I couldn't say for sure.