Sounds like a useful technique to use on an engine
owned by someone else :P This is likely safe enough on an engine
outdoors BUT... A rag saturated with gasoline in a diesel
boat's engine room, where nothing is sparkarrested, is just asking for a disasterous fire. Try this on a boat and you'll get "blasted" all right!
As I posted previously the rag is damp not saturated. Petrol is only combustible in a fuel/air mixture off between approximately 15% to 19% fuel
air mixture, any less there is not enough fuel
and any more there is not enough oxygen. Aerostart sprayed around in copious amounts can have the same result as saturating a rag with petrol (you end up with too much fuel and not enough oxygen in the combustion chamber). Too much aerostart sprayed around and not going into the intake can result in a decent explosion as well. Please note that I stated that rag was damp not wet (even I'm not that dumb).