William Watt says:

you could get the same effect from a modern engine by fouling the
sparkplugs, damaging the spark plug wires, putting dirt in the fuel tank,
or anything else you can think of that will cause the engine to miss, cough,
snort, and sometimes backfire.


I'll let you know when the body finally rots off my car - my engine must be
about right for "marine" use from the description ;-))

Steve