656 spark plugs fouling

If its excess gas (black smoke), try leaning the carb and insure the chokes opening n staying open and that the air cleaners not clogged up. If its burning oil (blue smoke), maybe run heavier oil like 20W 50 n see if it helps any.

Things that can extend plug life for oil burners or excess gas are to use shutters or thermostats or air flow restrictors on the radiator to get n keep the operating temp up to 180 and over. Of course, a good hot spark form good points n condensor n cap n rotor n wires helps. Try running the plug gap a tad wider and especially USE A HOTTER PLUG then you been using.

While running too rich is easily cured if shes burning oil youre kinda stuck. If worse comes to worse you could swap to an electronic ignition with a high energy high voltage coil and run a wide plug gap. Make sure the spark you have now is good n blue n visible as opposed to a faint thin wimpy yellow spark and if its weak check n replace the points n condensor if needed n try fresh HOTTER plugs n have good plug wires.

John T

You need to overhaul that engine. Anytime you foul plugs, you're pumping oil. Compression test is telling you that things are getting weak also.

Allan