Checked the valve runout on (2) cleaned up intake valves......straight as an arrow with maybe .0005-.001" run-out if that. I’m thinking the 3 cutter blades on the carbide cutter is creating a potato chip shape on the valve seat. Kind of like when a drill bit cuts a funky hole. The cutter pilot shaft is also dead straight spinning with an indicator. The reason the exhaust looked better is probably because of the extra hardness of the seat while cutting, it almost scrapes into the face instead of digging deep like the intake seats did. Wish Neway mentioned this in their literature, they allude to it but don't mention it directly.
Possible Solution:
O.K., I switched up my technique. The standard carbide cutting blades are 2 styles, a 12 teeth blade with an aggressive rake angle and no heel (i.e. flat surface). Another has 6 teeth with a long flat heel surface a different approach angle on the cutting edge. The first style blade is great for diving deep and plowing out those burn marks and pits when using a 0* thru 55* cutter, but can plow the material sometimes. The smoother cut blades are actually meant for 60-80* steeper valve port angles so the cutter doesn't plow too deep or quickly. Well, I switched out the blades over to the 45* cutter, think of it as a finishing pass on a lathe. Additional, I marked the T-handle so the "t" lines up with each blade to stabilize it from rocking side-side, like training wheel, minimizing any gouging that might occur.
Finally, I'm starting to see how truly bad the contact seal was with the previous valve seat cuts I made. The picture shows my first cleanup cut on the valve seat face which still shows a thin black line.......not good as the seat is concave, this is after hours of cutting with the previously mentioned carbide cutter (45* with aggressive blades). It's taking a lot of time to basically scrape the valve seat surface flat. When I stop feeling the scraping sound, that means all cutters are sitting on the surface equally and just sliding smoothly past, unless I apply lot's more pressure to start the cutting action again. Then, I paint the valve very lightly with some blue dye (prussian/engineer's blue) and I "bounce" the valve up and down like a hammer, making sure not to rotate the valve which would smear the imprint. Now, this bouncing is kind of an indicator of a good seat contact. A badly cut seat will absorb the bounce due to side deflection and hit with a "thud". With a well cut seat the valve will bounce high a few times with a nice ring to it, this is mentioned in passing by expert head builders.
Alternately, some guys paint the valve seat on the head and let the valve make a machined imprint on impact. This method is nice because you see the valve seat contact point on the head, and simultaneously you see the valve seat contact and positioning on the valve face itself, killing 2 birds with one stone. Both are important.
Anyway, with the first method If it leaves a clean blue circular stamp mark maybe .035-.050" wide of equal width 360*, it's good to go. Sort of like a rubber stamp imprint. Right now, most of the valves just contact in a few spots, showing how really bad the cut actually was. If the blue dye covers perfectly, it'll pass the vacuum test with zero problems. I'm thinking another 1-2 weeks to clean up the seats and then get the seat positioned correctly with respect to the valve which is the final final step. If you have OCD, this is a perfect project. I'm going nuts at this point redoing everything 100 times.
O.K., so I'll follow up in a week or so once I get some good results.