Measuring fuel pressure, Help me troubleshoot my Carbs.... Options

[thomasotten]

Well, I took the carbs off, and made sure the accelerator pumps were working, and adjusted them so the accelerator pump would be functional through the range of the carb's operation. Reinstalled the carbs, and put a this sealer on all four carb manifold gaskets, top and bottom. Get it running and balanced again, and same thing: the right side carb almost always backfires under acceleration. Occasionally is will backfire under idle. I am very frustrated. To recap, I have done:

Valve adjustment
Timing adjustment
Fuel pump pressure measured
Main and idle jet removal and cleaning
Balanced with synchrometer
Varied idle mixture from 2 to 3 turns

What have I not done? Time to send these away I think.

[type11969]

Did you clean out the acc pump circuits?
Did you verify that the acc pump check balls are seating properly?
Did you verify that the acc jets are the same size from side to side?
Did you verify that the acc jets are not partially clogged?
Did you measure the pump volume and try to equalize it from side to side?

You may consider getting new pump diaphrams and springs for both sides to rule them out.

-Chris

[Thack]

Sounds like you are too lean. Are "idle" jets perfectly clean or maybe too small?
Edit: is there an air screw that you have turned out too much letting in too much air? And if your selling them, how much?
I just thought of something. Have you checked compression? Maybe you have a broken valve spring or something. Sounds like the intake charge is coming right back through the carbs...