when i turn off my car it keeps sputtering

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Sick_Six225

72 Dodge Dart Swinger
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72 Dodge Dart Swinger, 3.7 225 Inline 6. When I turn off my car after driving for a little it sputters when I turn it off. How do I fix this and will this in the long run hurt my vehicle. thanks
 
When I drive the car it drives great no problems (of course after warming up) but as soon as a turn it off it sputters just for a second. Then when I start it back up no problems.
 
What does "on the dot" mean? These cars were not specified "for optimum drivability," they were spec'd for emissions, and many ran very retarded.

Bumping the timing as advanced as it will run without other problems will help the run-on problem

Other causes are running way too hot, carb out of adjustment, and as mentioned retarded timing. Obviously, local OD weather conditions affects the problem.
 
A high idle can cause it also. I don't know if it's possible to have manifold vacuum to the distributor vacuum advance on a slant, i'm not familiar enough with them, but that can add to it. You can always shut it off in gear. I've had a few built up high idle cars that I had to do that way.
 
Carb is adjusted, it’s not running hot at all and with the timing what do you recommend. Again the car is running smooth with no issues besides when turning it off.
 
The idle might be it, I need to get a Tach so I can make sure that the idle is were it needs to be at. Or is there another way I can find out were my idle is at?
 
A tach ,recommended.If you have a vacuum gauge,find peak vacuum.:in drive. Back the idle speed ,to where you need.
 
A tach ,recommended.If you have a vacuum gauge,find peak vacuum.:in drive. Back the idle speed ,to where you need.

Ok I do have a vacuum gauge so I will go ahead and try that

When "bomber" says find peak vacuum, he's speaking of setting the idle mixture screw.........After that, lower the idle speed screw to a acceptable level.

Let us know how it goes.
 
Look for a tach/dwell meter at garage sales. Many out there, and of no use on cars 1990+. Same for a timing light. Several things can make it "run on" or "diesel". One is carbon deposits on the head from running too rich at low speeds. Some say an "Italian tune-up" like running full throttle up hills can burn it off. Aren't you near the edge of the Cumberland Plateau for that?

A throttle too far open at idle is another. There were carbs in the late 70's thru 80's with "anti-diesel" solenoids which shut the throttle tightly to stop run on. I think they needed them then because of the emissions controls and settings they added that messed up a smooth idle and required the throttle be more open at idle. Thus, anything you can do to get a better idle and allow you to set the idle throttle more closed will help.
 
Maybe your car wants to keep cruising. LOL
But above posts should solve your problems.
 
Usually the cause of engine run on is something that attributes to too high an idle speed. Also, it can be detrimental to the engine. When an engine runs on, it is usually running backwards. The initial shock has broken or stripped many a timing chain.
 
It's not too high of an idle speed generally speaking, it's throttle blades too far open to maintain a desired idle speed, usually in gear. The drop from park to ingear is likely higher than normal.

Plenty of ways to tune a car, some better than others.

I'm out.
 
1. 3/8 spacer below the carb, do you have one?
2. fuel line mod, have you done it?
3. idle rpm?
4. Timing curve? 12 initial, 30 total around 2500rpm, 45 with vac advance is a good start
 
"the dot" may also be off.

If you want it timed right, use a cylinder stop and find actual TDC, get some cleaner on the balancer/ damper and throw some timing tape on it, hit it with as much initial advance as your fuel can handle and worry about the rest of the total timing if you decide to blueprint the distributor spring and weight stop (advance curve) and cap phasing. Initial timing is more important than total on a driver.
 
Not to hijack this thread, but would having timing set at 5BTDC or 10BTDC be more likely to cause this? I was running it at 10BTDC and had dieseling. It was also idling at around 850rpm. I changed timing to 5BTDC and also lowered idle to 750rpm. Not sure if what I did was correct, or if I should have left timing at 10. I wasn't getting any pinging at 10.
 
Otateral,
Read my post and others above. The more you can lower the idle speed, and thus close the resting throttle position more, the better it stops dieseling by choking off the air. The more advanced you set your spark timing, the better your mileage and performance, until you reach the knock limit, which depends on many things - gas used, air temperature, etc. Modern cars use a knock sensor and the spark controller keeps advancing timing until it knocks.
 
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