Checked a couple of things and tried a couple of things when I got home from work today.
- Vacuum ports are either capped (timed vacuum port, manifold vacuum port) or connected (PVC). I ordered some tubing for the distributor advance. But could still be leaks.
- Accelerator pump seems to work (engine off), but I could only see one port.
Tried to start the engine as I did yesterday (gravity tank, starting fluid), but with the choke closed; won’t start. Choke half closed; won’t start. Choke open, started. This time I didn’t touch the throttle. Idle was low and a bit rough but no backfiring. Engine died after a minute. Increased idle quarter turn. Now the engine ran for several minutes and then died. But the RPM’s went up and down and the 2 cup tank was almost empty so I suspect the fuel pressure was too low. Ordered a $20 electric fuel pump that I can run off my gas can and see if that clears up the idle. Then I might try and touch the accelerator .
Conclusion is yesterday’s backfiring was due to lean condition and maybe there are other issues like the accelerator pump.
Engine ran long enough I could check the power steering and it seemed OK. Baby steps.