Race fuel , race oils and rust.

[FED 387]

When we fog we just crank the engine over ignition OFF for about 20 seconds while spraying the fogging into the carb---yes when you restart it you do get a big puff of smoke but it dissipates in seconds---change out the warm up plugs put in the race plugs and you are good to go--been doing it this way for 30 years never any problems--FED 387