235 78 johnson timing problem

[jy118lfd]

I have a 78 235 tl johnason that runs rough and misfires at an idle and to about 1/8 throttle. I tried to sync the carbs and ing. But heres my problem. When I do the throttle pickup setting I get 5 degrees btdc, when I advance the throttle to do total as soon as I get to the point that the motor clears up the numbers disappear and I cant read the advance. I have an advance light and no matter how much I adjust it I cant not get a timing reading. When the moter comes down in rpm the timing marks come back and it runs rough and misses again. I have taken it out and it runs great with full power and rpm except at low throttle. I need help!!!

[clanton]

Use a timing light without the advance,

[Hooty]

Just ignore the pick-up timing and set the full advance timing, adjust idle speed with the idle speed adjustment screw and then see how it runs.c/6Hooty