Suggestions needed on 1978 Johnson 55

" 1978 Johnson 55EL78, won&#39

" 1978 Johnson 55EL78, won't idle, starts and runs if choked and kept on high idle but it spits and eventually dies at slow idle. I rebuilt the carbs, cleaned them better than new, replaced the floats, needle valves and seats, new gaskets ect., and carefully triple checked the float adjustment, disassembled the fuel pump, everything looked good there, cleaned and carefully reassembled. Replaced all the fuel lines and installed new clincher clamps. Has a new fuel tank, new gas/oil, tank is mounted almost level to the powerhead, bulb stays hard while and after engine is running. Checked the compression again, 130 on both cylinders. I had to rewire the engine, I used the correct guage wire and soldered every connection using new terminals and star washers.I cleaned all the wiring connections that I did'nt replace. Checked the spark, it's as blue as lightning on both coils. Replaced the spark plugs. All of this done progressively, no improvement except with carburators, the one on the top had a broken jet, since replaced. The floats are set level with the carburator base if the carb is held upside down, 5/32" airspace between float and carb base. I set the timing a month or so ago, I have messed with the linkages since. Could it be timing? The throttle roller is in the middle of the lines on the ramp. Could it be the reed valves? What symptoms do they give when bent or not seating? Do I need to set the floats higher? Do I need to adjust the linkages? The throttle plates and choke plates operate in near perfect unison.
Thanks, for any help you can offer. "

"Bryan.... The fuel primer bul

"Bryan.... The fuel primer bulb should not stay hard when the engine is running, nor should it colapse. Most bulbs are found in a horizontal position and when running, the fuel will drop down to the halfway level which is normal (no, I have no idea why, but that's the way they function).

Float level: Holding the carburetor body upside down, you would want the float to be ever so slightly off level (higher) on the end opposite the needle valve and hinge pin.

The problem you are describing would be related to either a engine that is not being supplied fuel properly, or carburetors that haven't been cleaned thoroughly. Did you remove and clean the fixed brass high speed jets that are located in the center bottom portion of the float chamber?

Also, the large brass tube that extends from the float chamber assy up into the upper body... that is a high speed nozzle. If there is a smaller tube within it, that is a slow speed fuel passageway which must be absolutely clear. Is it?

The carb throttle butterflies should just start to open when the first scribe mark on the cam (if there's more than one) aligns with the center of the carburetor roller. If it contacts prematurely, the engine will not idle and will more than likely spit back through the carbs (sounds like a mild backfire).

Let us know what you find.

Joe "

" Joe,
Man! did I ever clea

" Joe,
Man! did I ever clean those carbs thoroughly, I had a piece of piano wire that I used the clean the smaller tube (idle circuit), cleaned the lower jets, soaked and scrubbed, blew out with compressed air. I'm going to recheck the floats tommorrow, recheck the linkages and timing. I was reading my shop manual, it mentioned a flywheel key, I will check that if all else fails. The "mild backfire" you described it what I'm getting, the engine actually runs better if slightly choked, which made me think carburation also but after all the fuss I made over them I guess I was just in denial. Thanks for the help. I will report back. "

"Bryan.... The "Cam" t

"Bryan.... The "Cam" to "Roller" (synchronization)pickup, if opening the throttle too soon could result in that problem. Also, if the cam was adjusted incorrectly (threaded rod) petaining to timing (check your manual), even if the scribe to roller was correct, the throttle would be opening too soon.

The flywheel key..... If that key was even so slightly sheared, the engine would not run as the timing would be wrong. Note that the flywheel nut must be torqued to exactly 105 foot pounds.

Joe"