I'm in the process of sanding the primary ports in the lower half of the mainfold with 60 grit flapper wheels and kay rolls. The ports are somewhat "D" shaped, and I'm having trouble getting into the 90 degree corners of the "D" with either of the two tools mentioned above. The tapered rolls on the original list from Eastwood seem like they may do the job, but Mance removed them from the recommended tool list.

Should I open those corners up to a radius which I can hit with the kay roll? If I do that, how do I deal with the fact that the gasket will have the sharp edges of the "D", but the ports will be radiused?

The other option is to hit those areas by hand with sandpaper, but Mance made no mention of that.

If it's not clear what I'm talking about I can post pictures tonight.

Thanks for the help.

air travels in much the same manner as water. Under velocity it is thrown by centrifugal forces to the outside of ports/runners. This keeps the high velocity/high pressure air out in the rounded section of the ports and only slow-moving and boundary layer air near the inside sharp corners. I used a dremel with a 1/8" ball bur just to dress them near the primary/secondary inlets and only maybe 2" deep then feathered them out and didn't worry about the sharp intersecting angles beyond that.

Air flow within the IM is same principle and net effect as white-water in the outside of a turn on a fast flowing river/stream compared to the same water at/near the inside bank.