I have a black Horner twin (must be a 3.8), dual carb, CH Ignition, that has been a bear from day one. It's always been hard to start but once started runs fine. Engine has less than 10 hours run time on it. Took it out today and once again worked for an hour to get it to start and it would run the prime out but would not draw fuel on it's own, had a bubble in the line by the carb nipples and could see that fuel wasn't moving. Took the Walbro's apart and they are pristine inside, diaphrams are in good shape and all the jets are clean. Ignition battery shows 5.7 volts. When this engine runs it's a great engine but I can't for the life of me figure out why it's soooooo stinkin hard to start.
Is there a single carb conversion for this engine?

TIA,