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| | | | Joined: Jun 2010 Posts: 20 'Bolter | | 'Bolter Joined: Jun 2010 Posts: 20 | Good morning boys and girls, I have a '51 3800 Panel with a 350/T5. Runs fabulous. My problem is shutting it off. The motor will continue for 3 seconds after I turn off the key. It's not "Dieseling". Any suggestions?
Thanks in advance.
Ed Lupardo | | | | | Joined: Mar 2007 Posts: 4,215 Moderator | | Moderator Joined: Mar 2007 Posts: 4,215 | Ed, I would suggest posting this in the engine shop. A 350 engine doesn't really relate to a 1951 panel, likely more people will see your post. | | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | Does the truck have an electric fan? If so it will provide current till fan motor dies down. A diode or switched relay will solve.
Evan
| | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | I will assume with your self diagnosis that you do not have a carburetor? That is the only way you could say it's not dieseling.
Before we get the necessary info/history/back story and motor accessories, the first answers will be dieseling or too high of an idle....or a fancy "hot" spark plug. There are other heat related causes. Lean/rich/carbon/plugs/heat riser/exhaust leaks/timing.....also a bad ignition switch or wire or a miswire.
1. Is this a new motor install? or rebuild?
2. Does it have headers? Do they leak?
3. Been running ok until just recently this started happening?
4. Have you just completed any motor work/replacement of any parts. Done any timing?
5. Carburetor? Carburetor model? Hot rod motor parts?
6. Any wiring done recently?
7. Spark plug part number? Stock coil?
8. Mileage on motor?
9. Happens after short runs and long runs? If you start it up cold and run for two minutes, does it still run on?
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Jun 2010 Posts: 301 'Bolter | | 'Bolter Joined: Jun 2010 Posts: 301 | A Lot more information is needed to come up with an idea. What are you using for ignition? Points/condensor/coil? HEI? Aftermarket stuff like MSD?
1949 Chevy 3600
1975 W-25 Hurst Olds
1970 GMC 1/2 ton Fleetside
2010 Chevy Silverado
| | | | | Joined: Oct 2021 Posts: 6,686 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,686 | Timing too far advanced for the octane rating of the fuel you're using?
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Nov 2002 Posts: 2,763 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,763 | Shut it off 3 seconds before you are ready to shut it off????  Sorry, could not resist. Jon
Good carburetion is fuelish hot airThe most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes!The Carburetor Shop | | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | Shut it off 3 seconds before you are ready to shut it off???? Sorry, could not resist. Jon Very good Jon  Now that you say that, it dawned on me that 3 seconds could be really close to normal to stop the rotating mass after the last plug fires and sends a power stroke. (Momentum).
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | This sounds like a feedback from the alternator. Try running on just the battery with all the wiring disconnected from the charging system and see if the run-on happens.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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