Topic: 390 saga continues BACKFIRES

[Toploader]

Remember that the composition of gas has changed a lot since the late 60's/early 70's.

[1967 eight barrel]

I found 16 NOS BF32 plugs. I did used them and noted they fouled quickly because the vehicle was only being moved inside and out of the garage and shut down. I used to take it around the block to try and allow it to come up to temperature before putting it away. A couple whiny neighbors bitched because the front end wasn't on the vehicle. Now that it's back from paint I am reassembling the vehicle. I went through the engine and re-cammed it being the duration was too short and it was coming on too fast. The rich idle mixture kept the rings from seating the first time. I am trying to find someone in the Dallas area that has a stand at home to break it in on before putting the new engine in the vehicle.

[somethingspecial]

Unless I missed it, have you replaced the old fuel after sitting for three years.  My 390GT had the same problem, fouling plugs, back firing, etc.  I drained the fuel, flushed the line, refreshed the carb and now it runs great.  I checked all the things you mentioned and finally went to the old fuel, which was the culprit.  Mike

[Smokey 15]

 Good point. When I start a vehicle that has been sitting a long time, I unhook and plug the fuel line from the tank. I then run a fuel line into a 5 gallon can of fresh fuel.

[somethingspecial]

Any Update? What did you find out about the fuel?  Just curious. Mike

[1967 eight barrel]

Information that would have been helpful from the get-go. Anyone knows that fuel after three years degrades and is essentially varnish at that point. The only fuel I have even seen that may survive that long is race gas.