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Something is way off. So the radiator and engine are cool enough to touch? How far did you drive? I've read about a 2.3 liter ford that got to running temp of 210 in about ten minutes with no combustion (ran it on an electric motor just to see how long it would take just on fraction alone).
 

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Yes, your coolant temperature is way low which will result in poor oil performance and premature oil failure due to the presence of moisture (condensation) forming sludge.

On to the original issue... the most common cause of dieseling in an engine that isn't running hot is too much of the carburetor transition port/slot being exposed at idle (primaries and'/or secondaries).
 

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Discussion Starter · #23 ·
This is kind of out there but I’ve seen this happen to a buddy of mine: If you have an electric fan that’s not through a relay it can backfeed power to the ignition and cause the engine to run on until the fan comes to a stop. The fan basically acts like a generator.
I didn't know that. Something I will have to remember in the future. I am not running and electric fan. Evertything is mostly stock minus a newer radiator and my Edelbrock performance intake and Edelbrock AVS2 Carb.
 

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Discussion Starter · #24 ·
Something is way off. So the radiator and engine are cool enough to touch? How far did you drive? I've read about a 2.3 liter ford that got to running temp of 210 in about ten minutes with no combustion (ran it on an electric motor just to see how long it would take just on fraction alone).
Yesterday for a test. I took the car for a ride. About 20 miles round trip. Then I let the car sit in my garage running for another 10 minutes or so but before I did I looked at the radiator cap temp and it was only 182. The temp on the radiator cap thermostat was barely over 200 after 10 minutes. Using heatgun at the temp sending unit was 181, radiator to the engine tube was 132 and the engine back to radiator tube was only showing 190ish. So a little higher then normal after a longer drive. I never see temps around 230 or higher.
 

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Another possible causing of 'dieseling' are spark plugs that are too hot. Plugs come in temperature ranges (designed with a longer path between the tip and the body allowing the tip to get to a higher temperature). It is common in older cars for hotter plugs to be installed to burn off oil deposits caused by bad rings or valve stem seals. If the plug tips get too hot they will act like glow plugs. Check to see what spark plugs you have.
 

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Discussion Starter · #26 ·
I might have figured out the dieseling finally. Need to test it out more but I checked timing and it was good. I slightly advanced it some, adjusted the carb fuel mixture and adjusted down the idle a little. Took it for a drive to get it nice and warmed up. Start it and shut it down multiple times with no issues. Let it run in the garage until it was a even hotter then started and shut it down multiple times with no issues. First time I have been able to not have the dieseling occur. Usually would do it at least once out of every 3 or 4 times when turning the car off. Going to test it out more after work and this weekend.
 

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Good for you. Like another person mentioned, it's usually "ragged edge" timing/tuning that contributes. Everything is just a bit off.
When I came to California form Colorado I had a "high energy" cam from Crane installed. The static CR must have been way up there
because the only way I could shut the engine down was in gear. I changed out the cam to the 289HP unit and that was the end of that
issue.
 

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Try high adding an octane boost.
That's never a good band-aid. Most of the stuff on the market tends to leave combustion products in the chamber, which
build up and thermally make the situation worse for run-on.
 

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Yesterday for a test. I took the car for a ride. About 20 miles round trip. Then I let the car sit in my garage running for another 10 minutes or so but before I did I looked at the radiator cap temp and it was only 182. The temp on the radiator cap thermostat was barely over 200 after 10 minutes. Using heatgun at the temp sending unit was 181, radiator to the engine tube was 132 and the engine back to radiator tube was only showing 190ish. So a little higher then normal after a longer drive. I never see temps around 230 or higher.
Time for a thermostat to get those temps up.
 

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Discussion Starter · #30 · (Edited)
Time for a thermostat to get those temps up.
Planning on doing a new thermostat and sending unit. Thanks for the help everyone. So far so good. Been driving it all afternoon after the changes and still no dieseling going on. Fingers crossed but I am feeling like I have at least the dieseling issue sorted out hopefully. Will give it a few more days of driving to see if it does it. Hopefully I am on to my next issue that I have not been able to find anyone with a similar issue yet online. Will start a new topic on that if I cant find anything and see if anyone has any advice.

I wanted to thank everyone. Love working on my car and still learning the ins and outs of my 66, so I appreciate everyone's feedback and help. Great Community.
 
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