I would like to learn how to do it. I just need a little skinny die grinder and some attachments. then some practice of course.

A few questions: Has anyone measured the diameter of the port before and after porting work? And did the machinist take some material off of the valve guide? I wouldn't know how much to take off of that part? But definitely the spiral hone has stumped me How do they get that done?

Any info would be cool to talk about because this is a very interesting topic.

 

yeah its a fun topic.
On mine, the intake manifold ports were a little larger than the head ports by almost 2mm, so the head ports were opened to match, but that is all. they were matched up perfectly using diemakers ink squished between them.
the valve guides had a little shoulder on each side of them, and these shoulders were removed and the guides smoothed out because of their very porous appearance, but no significant material was removed to compromise integrity.
I would be guessing here, because I didn't watch, but it may be possible to get the spiral by using strips of emery cloth in the diegrinder - just spinning and flapping as you draw it in and out. don't know what grit to use, or if this was even the method, but that's really all it looks like. just fine shallow spirals spun through after all the grinding was done. it would have to be something flexible and flimsy like that, considering the irregular shapes it had to conform to. perhaps there's even a special tool made by some company for this purpose, i don't really know.
and who knows - maybe the spiral isn't even what its cracked up to be - might just be a sales pitch for that matter, or somebody's unproven opinion, but it does seem to make sense and it sure can't hurt.

 

could you use a flexible honing like they use for cylinders?

 

try a wire paint striper on a drill.

 

That is how I pollished my exhaust side, but I ended up with a very fine grit sand paper. It worked VERY well for that.