my uncle was just in town, he's an old millwright & a hotrodder. apparently around the start of the 60's/70's holley started selling water injectors that would bolt onto your intake manifold under the carb, the water mist works like an octane booster AND cleans the carbon out. apparently a lot of old tractors & other heavy machinery used to use similar devices.
if you want the easy way to clean the carbon out, remove the bellows below the throttle body, take a spray bottle with 2-3 ounce of water in it, start the engine and crack the throttle open slowly, too much & the engine will die (no airflow sensor to give it more fuel, and just mist a bit of the water in, too much & the engine will die, should leave you with sparkling combustion chambers.

maybe it doesn't really do anything, but my uncles dropping off his old holley mister for me to check out on monday. i thought it was pretty amazing that anyone would put water in their engine on purpose. anyone else know anything about this ? it seemed to work on my car, no more dieseling, of course i'm still going to check the timing & look for vacuum leaks next week.

ps. if you're going to try this, use your common sense, i don't want to hear any whining about how you didn't have a mister/spray bottle so you used the garden hose & hydraulic'd your engine.
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-- '82 245GL, B23E, K-cam, rotted out electrical wires, 350k km --