I'm playing with shooting 3 under, what is a good place to start with nock height. With split finger I usually was right around 5/8".
Right now I am at about 5/8" and getting excellent arrow flight.
on a bow tillered for split finger i place mine at 9/16. i also tie a small knot below my arrow nock.
I agree with what Sunshine said about the small knot below the arrow knock. For a long time I would get a bare shaft to shoot great, but every couple of shots I would still get poor arrow flight. Well, after doing a lot of reading I found out that with a high nock point, after releasing the arow, it will actually want to slide down the string before it leaves the bow....causing poor arrow flight. After tieing the small knot under the arrow, I no longer have the problem. My bare shafts will now fly just as well as my fletched arrows every time.
So if you shoot three under with a high knock point and always seem to get an arrow that does not fly quite right....try the small knot.
This is one thing I wish I would have figured out a long time ago! Hope this helps.
My knock is usaually about 5/8" to 3/4" depending on the bow.
I'm at 5/8 and all is well.