Frank, thanks for the information, although unexpected it makes sense now. I have carbs fitted, I assume then the best thing to do with my expensive possible white elephant system is to have it as an absolute last resort, with the nozzles aiming as far away from the intakes as possible, to save the car or occupants, and hopefully never to be used, and above all don't panic Captain Mainwaring.No ! Nick, are you using carbs or FI ?
This is what appears quite a simple question which gets more complicated as you understand the issues involved. The safest answer is don't have a fire in the first place, and if you do don't panic, more damage is caused by panic reaction than the fire itself. First always dump the residual fuel pressure in the system , I do this with a built in system that reacts instantly either the pumps or ignition is turned off. You can also kill an internal carb fire by keeping the engine turning over, each induction stroke will suck unburnt fuel into the manifold, and is a well used method of dealing with a fire in the carb trumpet. What you do not want is to suck the corrosive extinguishant into the engine, that's an immediate engine rebuild if you do!
If you have fuel leak else where in the fuel system , particularly on the pressurised side of the pumps, then it is imperitive that all all possible ignition sources are immediately isolated as far as possible, this happened in my case when I realised that I had liquid fuel being pumped over the engine side of the bulkhead window while doing well in excess of 130 mph at Stavelot on the Spa circuit in Belgium, killing all ignition sources whilst continuing at high speed to the pi t lane marshalls fire post, they were surprised to see a dead engined GT40 arriving at unabated speed with a very scared driver at the wheel, but the action saved a very big potentially car destroying fire. Frank
Frank,Good one Karl, I like the story . If running carbs, particularly Webers, it is, in my experience, essential to dump all residual fuel pressure from the system immediately you turn off the engine, and most particularly when the engine is very hot, and just as importantly to be using phenolic spacers between the inlet manifold and the carbs to reduce heat soak penetration into the carbs from the engine. Fire extinguishers are a last resort, but as you know yourself are the first thing you think of in this situation, so, as I said, first don't have a fire, then don't panic.