i was wondering if you milled a slot in the penut shape of the rotor housing that it would improve combustion

Your question isn't very clear but if I understand correctly it seems as though it will simply lower compression

yes it will but by aiding combustion will gain some power

No you will have a leaky and useless rororhousing.

DP

Do it and report back with your results.

send your engine here, i'll run it on the dyno

im in aus

You may have noticed that the trailing spark plug is recessed into a pocket, and the hole exposed to the combustion chamber is very small.



Why is that hole so small you might ask.



Because the burning mixture is below that upper apex seal as it crosses that little hole, and above that apex seal is a compressing mixture of fuel and air.



As you might imagine, it is important that no residual flame from that recess, or spark, or heated carbon flake be permitted to invade the next charge in line above that apex seal. Just one occurrance could destroy the engine. The hole is very small so as to minimize the probabillity that this can happen.



This is also the reason that you can run a wasted spark ignition on the leading plugs (fire both leading at the same time) but cannot run it on the trailing plugs, because one of them is always exposed to the next charge.



I have been advised by a competant builder that it is possible to mill a latteral slot through that little hole about the same width as the hole, so as to improve the performance of the trailing ignition. With the slot being the same hight as the hole, the actual exposure time in crackshaft degrees would be the same so as to not increase the danger of preignition.



I have never seen a housing with this trick installed. I have never seen a dyno sheet from a so modified engine.



I have read that some people just drill out the little hole to the same size as the leading hole, which would increase exposure time in crankshaft degrees. I have never seen a housing with that trick installed, or seen a dyno sheet from a so modified engine.



It sounds like a good housing going down the drain if you do these or any other grinding on the surface.



But the list of stuff that I have not seen is pretty long.



Lynn E. Hanover