Ok so i went to a car show today and when i got to the show and when i got home and shut it off it wanted to keep running. So what are the things that would cause that. When it finally stopped running backwards there was a little smoke coming out the center carb. Both times the car started right back up.

dieseling or run is generally caused by hot carbon build up in the cylinders, or lean fuel, or timing conditions causing the sparkplugs to be very hot igniting residual gas/fumes in the cylinders after the ignition is off, regardless of the "ignition" source, as the engine continues to "run on" it can still pull fuel into the combustion chamber running on for some time at times, the factory's cure for this was to have an "idle" solenoid, that would energize at start up and maintain curb idle, then when the ignition was shut off, De-energize and completely shut off air flow thru the carb by completely closing the throttle blades

You need to find the cause of your dieseling, it could be carbon build up, cheap gas, timing, air fuel ratio, etc, etc...a solenoid is merely a bandaid to the problem

what is your idle speed? but yes there is something else contributing/going on.

What do you know about this motor and compression ratio and fuel type used?
If the gas is old (more than 90 days)it will diesel a lot easier than fresh gas will
Remove two spark plugs, #1 and #2 and look at them, post a picture of them on here if you can
The spark plugs can tell you a lot if you know how to read them correctly

& Wallace racing has good plug reading pics/info.

I believe that i have the timing set at stock setting which i believe is 5 degrees BTDC. The engine is 30 over with 915 hp heads and the old MP purple shaft 484 cam. I'm running Sunoco 91 octane ethanel free gas.Both times it did it was after a fairly long idle.Have have the idle set at 900 in park and it drops to about 600 in gear.

Put it in gear and let out the clutch when you turn it off..

Auto, put in gear when you shut down...

Tried that to no avail!!

Obviously not the cure, but works till you get it sorted.
Did you try to use reverse?
That would be the steepest gear.

5 degrees initial, good luck there.

A 484 cam is going to need anywhere from 15-25 or more initial timing to get a decent idle profile.

Try tuning more initial into it and reset the idle speed/mixture screws. Try 20 initial. See if it shuts off OK. Then shorten up the mechanical to hit your to hit your total number.

Is this the first time it has done this or do you have a history of this ? If the first time - unless someone snuck in your garage and messed with your engine - maybe you should think of some fresh fuel.

Agreed, I'm running 19 on a bone stock 85 318 (+ cam adv 4 deg). I bet if you bump up your initial to 20 then retune it for that amt (lower the idle speed/tweak mixture screws) that the run on will dissappear. & then you would need to shorten the slots to keep the total at the known good ballpark 36-38.

The first question should be: Are you running an idle solenoid? If not, then the throttle is open to far (idle speed too high) and most likely the cause of the dieseling...the factory put them there for this very reason. See Dayclona's post above. Advancing the base ignition timing will allow you to close the throttle blades further at idle and should help with the dieseling...but check the total advance and limit the mechanical advance as necessary.

Is there away to check total advance when you just have the old style timing light?? I forgot to mention when i gave the motor specs.that it has a Mopar performance electronic ignition setup!

0.0632683" around the dampener circumference is (1) degree. 2&1/4" (2.246") is 35.5 degrees. CW from the TDC (OE) timing slit. EDIT you could use the dampener timing tab as a ruler if you have a straight shot access to reach it (no angle) but I think it is easier to cut a strip of paper & mark it at 15-17.5-20-22.5-25-27.5-30-35 or whatever you need with the math & calipers then use it as a ruler to make white paint marks on the dampener. clean it well first so they will last. getting the TDC slit at 6 o'clock makes it the easiest to get to.

915 heads Need to know pistons What final compression? More octane is what you need or hotter spark. In 1970 regular gas was 100 octane so 91 just does not cut it.

The idle solenoid was a crutch because they couldn't tune the car the way it should have been and still meet emission standards.

The car likely needs more initial timing and dialing in the carb. I run similar engines all the time and never have run on issues. None are anywhere close to a manuals recommendation for ignition timing events.

The 300 rpm drop in gear is another symptom of insufficient initial timing.

Mine would diesel if Sunoco 94 wasn't available and I had to use a lower octane.

OK so I got it much better. I advanced the timing to 15 degrees and thats all i could get because the idle screw is adjusted as far as it will go. It idles at 900 and i don,t have as much drop when in gear it is about 700. I also mixed AV gas with Sunoco 91 ethanol free gas. Shut it off and restarted it about 10 times and is perfect! Also the pipes are nice and grey. The reason i went with AV gas is to increase the octane because a drag racer said the pump gas of today isn't enough for my combo.

Try closing the secondaries a bit to get idle control with the idle speed screw. It may require removing the carb, using a hex key to back the stop screw on pass side out a bit