I am running around 13.2 - 13.4 at WOT. Carbed 540 with a QF 850 with mechanical secondaries. I am running just 1 sensor in my port side exhaust pipe. From reading , 12.8 would be more ideal. My idle is 14.8 and cruise is in the 13’s. Would a single jet size move it enough or ?

No, a single jet # will most likely get you about .2 or so afr difference, if your ever gonna just put it on the dashboard and leave it there, Id tune for mid to low 12s at wot, what intake are you running?

I have a Dart single plane. I have a gauge set up kinda temporary.. maybe go up 4 and see where I’m at ?
lol. In the photo it is reading 8 but it has a count down mode from 20 until it reads ..

I am probably going to have to do some re tuning as I am going to instal a Pcv valve. I picked up a Wegner tunable Pcv and am going to plumb it through a catch can.

Yes, I would go up 4 (on secondary's) but look hard at cruising afrs and adjust your primary's and air bleeds/ powervalve if necessary FIRST. The Dart intake has horrible distribution so keep that in mind, from what I seen dynoing engines with them you definitely have a couple cylinders at wot that are a minimum of 1.5, prob more like 2, 2.5 points LEANER than your tailpipe average.
I built and dynoed a 502 with dart heads, vic jr intake and a customer provided 850 XP carb (new), I dont remember the exact amount of jetting I went up but it was like 10 numbers on secondarys, btw, if you have to go up too far on primarys and your cruise goes to rich below point the PV is open, go back down in jets and drill your PV feeds bigger, will lean out you cruise with pv closed and give you more PE when pv is open, Smitty

Thanks for the info , Smitty ! I remember reading one of your posts describing that. As it stands now , I am really happy with my idle and cruise numbers. There are a lot of no wake and idle zones in my neck of the woods and my transom is clean. So here’s another one for you. My engine idles happiest with about 20 degrees of timing. The black msd bushing though has 18 degrees of advance. So at 16 degrees I get a drop in idle going into gear. I have seen a 14 degree bushing advertised. So is that a good option or locking it out and running a Daytona Sensors box ? I hate messing with it too much.