Porters - favorite type of cutting burr for alum heads?

ditto..
pretty much need one of each..
but the barrel with flat sides is good for gasket matching the intake flange.
acorn shapes and like are good for runners and guides.
the balls are good for troth's and corners.

What do you use on cast iron heads?

Thanks

I've got a selection of shapes, diameters & cutting styles (aluma-cut, single & double-cut) and have played around w/ different combinations, depending upon the area of the port I'm working on and how much material I'm comfortable removing quickly.

Not sure if it's my choice of grinder speeds (I've got a rheostat w/ my Makita to adjust it as necessary), porting technique or ???, but I've had very mixed results when using aluma-cut burrs... Some folks look like they get a pretty consistent semi-rough surface finish with them, but my results very from "just OK" to looking like a beaver with a taste for aluminum went nuts in the port.

FWIW, I use either Mondello's cutting fluid or Eastwood's "grinder grease" with the less aggressive single & double-cut burrs. They both do a decent job of keeping the teeth from loading up too quickly before I periodically clean them w/ a wire brush. However, there are times where I really want to remove material faster than those do.

Haven't tried RuffStuff's high-helix design before, although I'd noticed them when checking out their web site previously.