hey, talking about a something u didn't mention in the article, on the valve seat, put a 45,30,then a 15 degree angle,u can do it to hardened seats but it'll eat up your stones and they do get costly , try this out on your flow bench with your valve angles  

i am not involved with the artical... most better equipped shops now use cutters  on their seat and guide machines...

i still use stones on the few that i grind at home... and i use all three angles every time..
the sioux machine i use was last sold in 1946.


the  seat angle is many times 44 or 45 degrees..   cutting the 30 on the top moves the seat down.

the 60 degree moves it up.. ..

the 3 cuts when done right allows you to put the seat on the proper area of the valve face.. the proper width of the seat contact face also.

if i had the extra stones i could do 15 and 70 degree cuts and come out with a 5 angle valve job...

there area a lot of tricks that will never be writen down and printed anywhere..  

if you run a seat insert that has a larger bore that can increase the flow.. but it moves the contact area out on the valve face and the valve won't last as long...


for more information .. google  goodson .. they have a neat engine rebuilding tool and equipment catalog..  and have replacment supplys for valve grinding equipment...

if you want to learn more about valve grinding..   engine-builder.c  has a great archive of past articals...  

oh.. and i on special engines grind the valve face,  do the back cut and chuck it in a high speed drill press (not too tight)  and polish the back of the valve  by holding sandpaper off of a roll on it.. then a light redress only on the face again...this works really well... do try,  not to knick the valve stems in the chuck...


wayne