I'm a little confused as how you are going to accomplish this multi-angled valve job for a couple reasons :
- no matter how you are going to remove the "knick" in the seat you'll have to remove the same amount of material so how is cutting or lapping different in that respect?
- "lapping the crap out of it" to get the angles matched is something I don't see working. When I lapped my cars cylinder head before taking it to the automotive machine shop for cleaning and resurfacing i asked the guy how my lap job was, he said it could use a little bit more. When i said i had been afraid to go too far with it he just laughed and said "you could be at it all day and not take too much off but good luck trying!" Lol.
By the time you add up tooling, possible replacement of valve seats, valves ect. and add a little something in for you time I'd imagine you'll surpass the costs of paying for a professional job.
I appreciate what you're trying to accomplish here as I'm the kind of guy that does (almost) everything myself so please don't take what I've said as disrespect, when it comes to that kind of precision that requires expensive equipment I prefer to let the pros that have it do their thing!
The lapping processThe valve will only seat on one of the angles (usually the 45 degree) and then you have angles above and below the 45. When you lap a valve you are just lightly grinding down the 45 degree seat area. You can't lap different angles into the seat. However, if you don't get the above and below angles absolutely perfect it will still seat properly as long as you have a conical and well mated 45. So I could cut the 60, then 45 and then 30 and if the 45 wasn't perfect then I could "lap the crap out of it" with the valve to ensure it was conical and well mated on the mating surface of the valve/seat sealing surface. If I just lapped the knick out of the 45 angle then the seat would be too deep in the pocket. You have to keep the seat in the middle portion of the 45. So I would cut the angles, blue it to check the seal area and then leave it a little high so that I could "lap the crap out of it" to make up any out-of-roundness to be sure the valve seats in conical and at the right seat width and depth.
I'm not sure what isn't clear about the difference between lapping and cutting multi angles on a valve seat. You can't lap in extra seat angles, you have to cut or grind them into the valve seat. The stock valve seats only have a 45 degree angle. It goes from 90 degrees up, 45 degree for the seat and then 180 degrees. I want to cut in a 60 degree below the 45 and a 30 degree above the 45.
The reason I want to do it myself is because every engine wants a different valve job. You run the head on a dry flowbench to check dry numbers and then wet flow to check fuel seperation, velocities, etc. You can keep adjusting minor alterations and make huge improvements in flow numbers as well as fuel suspension characteristics. I wonder how much it would be to drive 45 minutes atleast several times and have someone try to cut them exactly how you are thinking in your head. It just makes better sense to do it yourself.
I'm not spending $900, or even $250, on a kit to cut the valve seats on a silly $99 stock yardkart engine. Not sure what you don't get about that either. Just like I won't spend an equal amount of money driving to wherever just to bother an engine shop to try to get the valve seats to what I want. However, I would rather do it myself and would pay extra for it because I will still have the tools for future projects, I would be able to dial them in to my liking, gain experience and have the satisfaction of knowing that I did it myself. A $99 yard kart engine is a perfect platform for trying to accomplish things yourself.
Sorry, just thinking out loud...
TIF, didn't you have a lathe?
couldn't you grind and cut the valve poppet into a matching thread and
use the original stem as a pilot?
that should be fairly limited in play, no?
a short shaft welded on and a flexible shaft coupling to compensate for offsets in the powertool... might work, no?
'sid
PS again nevermind me, might be something I'm missing in cutting valve seats..
never done such thing myself (only ever had it done once and didn't even looked over his shoulder back then)
No, I don't have a lathe. I could make my own pilot and whole set-up for the most part if I did. The stock valves are more tight than the pilot I got with the kit though. Good thinking and thanks for your comment but I don't have a lathe.