Saw something ref tuning a bow for 3 under shooting, but can't find the thread.  The original writer said he doesn't worry about tillering, but adjusts his nock point for 3 under shooting and has never had a problem.  Should the nock be above center or below center for three under?  How much?

Start around 5/8" above center. You may have to go as high as 7/8" depending on your setup.

Man I am about 3/4 inch nock higher than center with most of my set-ups. All of my bows are tillered for split. I usually start at 1/2 inch above and start bareshafting from there. OL Adcocks tuning tutorial on his website will help alot with bareshaft tuning, as will multiple resources here. Others may not quite be as high as mine but for whatever reason that's where the bow/arrows tune the best for me.

You will need to find the sweet spot for your bow, I have shot some at 1/2 and others at 3/4. and a few lower than 1/2. I hope this helps.

I shoot 3 finger. I start at 1/2" above horizontal on all my bows. For most of my bows 1/2" is where I leave it.

Most of my bows have always shot well at 5/8 to 9/16...when I shot split it was usually around 1/2......Its all part of tuning the bow for how YOU shoot.

3/4 to 7/8" above center on my set ups.
I use a brass crimp nock on the top, and a tie-on
point from the bottom.
I tend to heel the nock pretty hard at full draw,
and for some reason, the nock will slide down the string a mite when I release, hence the need
for the bottom nocking point.

THX much

Just tune as normal and when you are finshed you will find that more often than not the nock point will be a little high as mentioned above

I'm usually 3/4" above also.