Turn off the ignition and it backfired like a bomb went off.... many 308 owners know what I mean... I understand this has been discussed in many thread and its become a problem that all 308 carb owners put up with. I have this problem for year... rebuilt carb with all new jets, new spark plugs, new coils, new ignition wires, many times of setting and resetting carbs, the back fire when turn off igintion still there... I have to cope with it by waiting inside the car and let it idle for a minute before turning off... Then, two weeks ago the distributor rotor broke while I was driving... I changed the rotor and now the backfire is GONE.... idling is better too. It idles steadier at 1000 rpm and the engine sound is clam... and no more backfire, may be this is just my case. But electrical and ignition of the 308 is for sure relate to the backfire....
My Lotus once had the "308 backfire" too. It can be caused by several things; there's no one cause. Mine was simple too lean a mixture. In your case, it was probably the ignition not giving one last spark at shut down, so an unburned charge went to your hot exhaust system and ignited on shutdown. Waiting at idle before shutdown cooled the exhaust enough to prevent it. Your new rotor, not being worn like the old one, solved the problem. Ken
