Carb Dieseling

[ronskydivepops]

Hope someone can give me some advice on this. My engine in my 71 GT is original and will need rebuilding before long. I've got the stock mechanical fuel pump with a weber. Points and timing are all correct, timed with a timing light. Plugs, wires, cap, etc. are all only a few months old. I have a problem with the engine bogging down when I floor the gas, but I think that may be due to my fuel pump, which I'm switching out to an electric Carter next week. My problem is that when I shut it down it runs on most of the time. Before I timed it with the timing light it seemed to shut down ok, but I had not driven it then. It does not do this all the time, just most of the time..

[GTJIM]

A sure sign of carbon build up in the combustion chamber and/or that someone has put "hotter" spark plugs in there to try and "burn" the oil off them. There has to be something red hot in the combustion chamber to ignite the mixture after the ignition is turned off.
There was some talk about "decarbonising" the combustion chamber by running the motor while pouring a small amount of water or ATF down the carb recently - have a search as it may be worth a try ........

[hrcollinsjr]

Most of the times that I've observed run on has been because the idle speed was too high.

Water, ATF, and I believe Sea Foam are supposed to be possible cures. Do the search thing as GTJim has suggested and come up with more details.

HTH,
Harold

[ronskydivepops]

Thanks Jim. I've tried the water routine a few years back. I was a little leary at first with pouring water in an engine but I tried it when I first got the car 4 1/2 years ago and it actually worked. I could see the black carbon coming out the exhaust. Guess I'll give it another try. The engine could have quite a bit of carbon in the chambers, I've had the engine running with the timing unset and the carb unadjusted for quite some time. Only recently did I set the timing and carb adjustments properly. Pulled the plugs and there is no build up but, they are a bit black as the engine is old and burns some oil. Just don't want to rebuild it yet. That will be my next project this summer as it is too hot to drive here in Florida without ac and a black interior. Any good advice for a rebuild? I want to keep it stock, but I'd like more power. Maybe a 2.0 or larger without too much modification I hope. I've got a new clutch to put in but no spare engine parts. Im looking around for a used block and head to rebuild but wonder if maybe I should check out Opel GT source for a used 2.0. Thanks again Jim.

[Willy_g77]

used to have the same problem...put pertronix in and flame thrower coil... never happen again! those things are life savers!!!