Only problem with this is, that you might experience slightly faster wear on your guides. But one doesn't really expect a "racing" engine to last for ever though, so it's probably ok to do.

For turbo applications at least, I wouldn't enlarge the exhaust ports to much. Larger ports means less velocity in the gasses, which means slower spool up on the turbine and greater lag... None of which are desirable properties for a turbo application.

This is also why I sometimes frown on turbo manifolds that use excessively large runners. It looks mean as, but it serves no real useful purpose...

I'm no turbo expert, but one learns a lot by listening to what others, that do have the experience, say. Reading also helps, as do this site...

yea apparently the mod to the valve stem increases wear and can eventually lossen them, something i have to keep an eye on, pigdog, i did a similar thing to the exhaust ports, didnt enlarge them too much just got rid of the step and smoothed/rounded the stem/area down. Ill see if i have a better pic somewere

yeah i was just trying to get rid of the huge step that is in the exhaust ports, would be good if i caoul take the valve stem out and port it then put it back in

but dont really feel like getting new valve stems

they're valve guides. the stem is part of the valve. you can punch them out. common practice is to punch them out, shorten slightly, taper them and refit. I wouldn't expect too much of a service life out of them cut that short on the inlet side.

but wear might not be so bad on a turbo engine with much less radical cam than hot atmo engines.

thats what i meant valve guides

so you dont have to get new ones after punching them out, cant say ive ever taken any out....something to do to one of my spare heads when im bored

would make the porting process alot easier for me

If you knock them out, get new ones, don't fit them back. One invariably damages one, and it comes back and bites you when you least want it to. We used to heat the head with a torch, the hole expands, and you could sometimes push them in by hand.

ive got a press to do that sorta stuff