Opening-up the "port pocket" area just under the valve seat is the place where you will get the most gain for the least amount of work. There is a sharp edge where the valve seat machining stops and the "as cast" port walls start, this sharp edge needs to be removed.
If you plan to use oversize valves, "rough-in" the new valve seat location first and then grind-out any extra metal to the inside of the new seat. Grind straight down from the inner seat edge, do not cut metal underneath the seat, that metal will be needed for later valve seat grinding and helps heat transfer.
DD
http://www.dutra.org/pictures/engine/pa ... ction1.jpg
(that's me trying to blink a metal filing out)
) but I may need to bother you with this 2 (or 3) q's
so if after 1k mi is "cooked" for good I may have to replace that... that would be a nice time for installing studs instead of bolts. I'm not sure yet about this, but I'm getting poor idle till 4~5 min after dead cold startup or 2 min after letting it rest for like 2~4 hs. I have to choke it at about 1300 rpm those first mins or I get stalling and erratic idle speed or sputtering when steppin on it from 1200~1500 rpm in 3rd gear. Anyway I'd like to port one spare head and do "all at once"... so I may wait. My current head is what I believed to be mildly ported but I just removed too little on the seats and smoothed out the valvle boss... let's say just surface clean compared to what I've saw. I think that a good porting job would make my long duration increased lift cam, free flow headers and recurved distributor shine to their best.