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Hi.
I have ported a few heads with a Dremel clone with a flexi shaft and a carbide bit and stones. Just be shure to get a non agressive fine one . preferably without a chip breaker as it will bounce less and it does not have enough power for anything. 4mm diameter will be about max.
I do have a proper grinder ( a 800 watt Pro-tool with rpm control) but as the ports are tight it need quite a bit of practice and can be dangerous. still use a dremel for near seats and finishing ( flap wheels tend to work well in combination with sanding rolls 80 -120 grit)r
it is also not cheap and you need a set of long shafted burrs that need to be cut down a bit as too long gives very scary tool whip.
ergo:
a whole collection of stones will work if patient (they wear/beak sometimes within minutes) especially in the beginning it is good to use a stone with a radius near to what shape you are aiming for. that avoids unwanted golf ball style dimples.
knowing where to take off metal and what not to touch is actually most important. I'd suggest reading Vizards Yellow book. it is pretty good. although some of the info is a bit scattered.
But what you need:
safety glasses (i hate them.. but metal in the eye sucks!),
dust mask.. grinding dust in the lungs sucks (and not in a good way, wiki silicosis..)
thin gloves: caaaast irn dust seems to embed in you fingers like a mother
Vacuum cleaner: Keep the dirt from obscuring vision and being crap all over you shop..getting into freshly build engines ruining them after a short while, even then the dust will settle down and with a little moisture will surprisingly effectively rust/weld to whatever it landed on. so keeing the dust under control is paramount.
Idealy a downdraught table.
Light: After a few blackouts caused by a shorted out desk lamp (metal filings....guess what) i bought a sealed Vertex Lamp for use on metal working machines. but battery powered would work too for light within the port combined with some kind of floodlight . Some dude on the speedtalk board made up a vacuum light by adding a lamp to the bended section the vacuum hole.. never got around to making one.
straight edge small enough to stick into ports for judging the flatness of your grinding.
Vernier calipers.
Dummy valves ( old valves to protect the seats while grinding.
Machinist blue/red/ whatever colour.. for marking out.
Burrs: carbide. fine spiral cut flame or egg burr if you only have one or two. 6-10mm diam with preferred for a big grinder. 3.5 inch shaft.
that will give you acces to most of the port. a dremel flex shaft without the locking collar plastic bits rather good as well.
A router with speed control turns out to be excellent for machining chambers even, flat and controlled. use the shape of the stone of burr to sport the radius of the chamber wall to floor.
Mark out the outlines of the chamber well and stay within them ! all theory aside: that last few microns will gain very little ..and an engine which does not hold a head gasket is pretty useless.
Edited by Sir Yun on 18th Jun, 2010.
That sir, is not rust, it is the progressive mass reduction system
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