340 Initial timing questions

So my question is; why are you running to 900/1000 idle rpm?

I have a 230/237/110 FTH cam with about the same lift, but with much more advertised duration (276/286/[email protected]), and mine will idle down to 550rpm pulling itself along at 4 mph with 3.55s and a 3.09 low gear in the A833, with an ancient Holley 750DP. The neutral idle speed is whatever I set the timing to but no higher than 750 (12/14).
The secret is to set the transfer slot exposure to a little taller than wide, then leaving the idle speed screw alone. To set the idle speed you then use idle-air-bypass and timing. My idle timing is 12 to 14. To idle down to 550 I retard the timing to 5*(with a dash-mounted, dial-back, Jacobs timing-delay box). But the T-slot exposure remains the same, and the accelerator pump adjustments remain the same, so I get no tip in sag or bog/hesitation.
If you do it your way with 22 or more initial timing, then,to get the idle speed down to 700 or so, you will nearly shut off the transfers and have to open the mixture screws to full rich, so it will still idle. Then when you give it throttle, the transfers will be very lazy to get started and she may hesitate and even stall. To compensate you will increase the pumpshot, and it still won't be happy until the idle speed is increased, bringing the transfers back on line. In the end it is driveable, idles way too high, and sucks gas pretty bad.
Do yourself a favor, set the transfer slot exposure and start over; who cares what the idle timing is! If you have an automatic that cam wants a 2800rpm or more stall, so you should not care even a tiny bit what the timing is below the stall speed. Then, as soon as the car gets moving, the Rs are rocketing and you still hardly care what the timing is because she will almost instantly be at max WOT timing.And it will never be below max timing again at WOT, unless the Rs fall to below your "all-in-by" during a shift, in which case you shifted too early,lol.
The only time you care about timing between ~3600 and the stall, is when you are cruising in that zone, in second gear....... But that is where the Vcan makes up the difference, so modify yours to get about 22/24 degrees,( instead of the miserable 9* they often come with) and then you're in business.

Now if you have a manual trans, that's a whole nuther story