Lets say I have a half tank (10 gallons or so) of crappy low octane gas in my tank the previous owner put in that makes my 1970 455 run like $hit and diesel when turned off. I know draining it is one answer but I already have too much older gas laying around for my lawnmower/snowblowers. Would some CAM 2 or equivalent added to it "refurbish" it? Or should I go buy more gas containers and drain. I can't seem to give this stuff away and I just don't like the idea of 20-30 gallons of gas around the garage with kids, pets. Also, is dieseling bad for the engine? This thing will go for 30 seconds. Bad carbon build up I'm sure.

 

If your car diesels when you shut it off then make sure everything is working properly. I would just run it with the bad gas until the tank is near empty and fill it up with good gas. If it continues to diesel then you know the gas wasn't the problem. You can usually shut the ignition off in drive to prevent dieseling.

 

Really? OK that seems like a excellent short term solution until I find out whats going on. At least when I work on it now it won't be chugging on for 30 seconds or so spewing those noxious fumes Nasty! Thanks
Tom.

 

I agree with Jesse, the problem may not be your fuel. Look more closely at your tune-up and be sure the carburetor throttle plate closes when you turn off the engine. But don't look straight down over the top, you might get a surprise.

 

Yeah, the carb looks original and never rebuilt. So your saying maybe the air/fuel mix is off? Already did plugs, wires, cap, rotor, points, set dwell (you guys helped me through that thank you). Timing next. I was going to set timing after dwell that day but I shut off the car to change from the meter to the light and the car dieseled for a minute or more and poisoned my air. Had to go outside. Pissed me off. So maybe a sticky throttle plate is the problem. It only deisels when warmed up to temp. A little carb cleaner? You think? Thanks.
Tom