1963 Ford 4000 runs on

4 cylinder gas. After I shut it off it contines to run on for a little bit. My idle is about 700rpm. Am I running to rich? Any ideas. It is SOS so cannot kill it with the tranny.

Might be too rich but I would check the timing first.

Idle to fast, set it down to 600.

I'm with Royse. Check the timing first.

This subject was brought up a day or two ago.. I am of the belief that timing cannot be the problem. How can there be spark at the sparkplugs with the switch off? Carbon deposits in the engine can create this, along with hi idle speed. Get below 600 rpm and remove some of the deposits like maybe some fuel additive.

My 62 4000 SOS does the same thing. I don't think
the idle is too fast on mine. I think it's little
hot carbon flakes that ignite the left over fuel.

(quoted from post at 21:54:49 10/26/14) This subject was brought up a day or two ago.. I am of the belief that timing cannot be the problem.

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Sorry Wayne! You're in error here. I have an identical tractor to the subject tractor of this post. It had this problem, run-on. As soon as the timing was corrected, the problem disappeared.

Again I say, check the timing first!

Larry! How can no spark at the plugs effect timing?

It's not the mixture.

Set the idle to the specified 400 - 450 RPM hot.

Return the engine to idle before shutting down.

Dean

(quoted from post at 22:09:46 10/26/14) Larry! How can no spark at the plugs effect timing?

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I cannot explain it, Wayne! But I know from personal experience that timing does matter!!!!

It takes all kinds of people to make he world go 'round, so I guess I'll agree that we disagree.

I have seen this a few times and have seen it solved by correcting timing. We know that running with the timing significantly off will cause an engine to run hot. The excess heat can cause points of carbon to be hot enough to provide an ignition source, without a spark.

All,
I'm with Dean here. Get the idle down first. 700 is way too high. Some of the other reasons may be contributing, but that engine can't stop with that much momentum.
Keith

.
.
One would think.... no spark - no run........

These older engines have had years to develop a nice coating
of carbon on the valves, chamber, plugs, etc.
and after decent run time, some of this carbon will glow hot......

Glowing hot = same as spark

Timing MAY be a factor if causing the engine to run hotter,
but the carbon deposits are the real culprit.

Run a tank of gas with a can of Seafoam through it,
and the carbon will be diminished (hopefully) to the point of
being 'all better'

.

timing off CAN make the engine run hotter.. hot enough to make your exhaust manifold glow dull red!

that can contribute to run on.

that's why all the comments to say to always make sure timing is correct!

When an engine keeps running after you shut it off its because
the timing has made it run hot. When your manifold gets too hot
and you shut off the tractor the momentum carries your fuel air
mixture up into the exauste side of things causing ignition. This
will happen when the exauste valve is still a little open. If you
look carefully when it keeps running It is actually running
backwards. This is called dieseling. Fix the timing and adjust
the carb a little bit and it will be fine.

(quoted from post at 11:54:32 10/27/14) When an engine keeps running after you shut it off its because
the timing has made it run hot. When your manifold gets too hot
and you shut off the tractor the momentum carries your fuel air
mixture up into the exauste side of things causing ignition. This
will happen when the exauste valve is still a little open. If you
look carefully when it keeps running It is actually running
backwards. This is called dieseling. Fix the timing and adjust
the carb a little bit and it will be fine.

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Substantially off there Jr. better back track and review your information. you bring up some good points but they just aren't meshing.

I would agree with those who posted idle speed and timing:

Idle speed: My operators manual specifies an idle speed of 450 - 475 RPM. After setting the idle speed, adjust the idle mixture screw to obtain the best idle, start at one turn open, per the manual. If the idle speed has increased as a result of setting the mixture screw then repeat the above until the proper idle speed is obtained.

Reducing the idle speed closes the throttle plate, reducing the fuel air mixture going into the engine. Less fuel air mixture means less heat. In addition, since the engine is running slower there is more time between combustion events allowing possible ignition sources to cool.

Timing: My operators manual specifies initial timing be set at 4 degrees BTDC at 475 RPM. The advance timing is 20 degrees at 2000 RPM. If the timing was retarted it is likely you will find the idle speed has increased with the timing set as per specified. Reset the idle speed to the specified value.

Retarted timing typically requires a greater throttle opening to maintain idle speed. This results in a increased air fuel mixture going into the engine resulting in more heat. To minimize possible ignitions sources less heat is desired.

Note - The normal way would be to set the timing. then the idle speed. However, since your problem is "run on" switching it around allows one the see the effect of timing on the throttle plate opening.

Tie a string on the coil wire to kill it, until you find out what is
wrong.

(quoted from post at 20:35:45 10/27/14) Tie a string on the coil wire to kill it, until you find out what is
wrong.

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What????? jerking the coil wire won't do any more than turning off the switch will.

(quoted from post at 19:09:27 10/27/14)

(quoted from post at 20:35:45 10/27/14) Tie a string on the coil wire to kill it, until you find out what is
wrong.

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What????? jerking the coil wire won't do any more than turning off the switch will.

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Will pull the end off the wire too.

Thanks all for the advice, especially Indiana Ken. Turns out the timing was retarded. At 2000rpm it was about 16 so bumped it up to 24. So when I tried to idle it down it would kill. Now I have it idling at about 450. Amazing how low they idle. At idle though the timing is about 7 or 8 not 4 as recommended. Engine shuts right off now. Nice.
Weird thing though. As it was sitting in the shed running at 2000 and then back and forth to idle it overheated. After it cooled down I took it out and drove around and it was fine. I am thinking thermostat is a little sticky.