Ok new problem. :(
We are dealing with a 120hp mecruiser from a 1965 Starcraft Cheiftain.
Idles just fine.
Try and rev it up over idle and it backfires badly.
All new ignition parts. Plugs, cap, rotor and wires.
New fuel filter. (2)
Carb cleaned and new kit installed. (3) times.
Changed the...