As Jerry mentioned above, either too many carbs (or one too few
) that are oversize for the engine.
What you have definitely is not the ideal carburetion system; but several enthusiasts have made it work (sort of).
So, before throwing rocks at your Fenton:
(1) Did the engine run well prior to installing the dual carbs?
(2) Have you done a compression test on the engine?
(3) Have you verified that the advance mechanism in the distributor is functional, AND correctly adjusted?
(4) Do you still have points and condenser, or has someone talked you into a DOWNGRADE of an electronic whizbang for the ignition? If points, have they been set prior to timing? Is the condenser new?
(5) What is the value of your idle vacuum? Have you checked for a vacuum leak?
As to the failure of the Uni-Syn??? Over 60 years of playing with multiple carbs, I have adjusted hundreds using a Uni-Syn, and to date have never found an at-least semi-healthy engine to fail to allow readings; however, I must admit I have yet to even think about the consideration of trying one on dual Rochester B's.
And even though I believe you can get better carburetion by hiring a 15-year-old to stand on the running board and pour gas into the engine from a leaky boot than one B
(let alone two), I personally believe you are looking at the wrong culprit!
Suggest you start with the basics: (1) Compression test, (2) Ignition test, and then think about the carb(s).
Jon.
