Stromberg WW Main Jetting Recommendation

[Rddau]

Originally Posted by geezer#99

Backfire thru the carb is usually lean mixture and retarded timing.
What main jet is in it now?
What is your initial timing set at?
How much vacuum at idle?

Don't know the main jet yet but it was fine before the rebuild.
Timing is at 10 BTDC with vac line plugged.
Mechanical advance works.
Vacuum advance works.
Vacuum is low, don't remember the number. Vac line to distributor is connected, there are no other ports.
Float is slightly lower than recommended. Confirmed by local carb guy who suggested the lower setting. At recommended setting it blew fuel through.
Dwell is at 33. All new points, condenser, plugs, wires. Still the old coil though.
Accelerator pump works.
There is no PVC valve. See pictures. The hose that is open goes into the air cleaner. I do not have anywhere to put one as I've seen in other pictures here at the bottom of the carb.

The strange thing to me is I've had this running really nice but I can't go more than a couple miles. I end up choking it and pumping the throttle just to limp back home.