What causes it too diesel when I shut it off? Not everytime, sometimes when it is cold and sometimes when it is hot. Been experimenting with the timing and have the base at 14* right now which is prolly why it started this, but what actually causes this?

Thanks,

 

HI

Mine does this too.. It stopped alot when I put my timing to 6* But it happend again today.. My carb is the last old part on my car since the new engine and I know its running way rich.. Maybe Running rich causes this?

 

Not sure as to the why but i know a easy fix....


Shut it off in Gear (Reverse or Drive dosent matter)

Works every time for me.

Just a suggestion

 

Ya that does work. And iv put it in Park and shut it down at the same time with my left hand and that works for me too.. Maybe because the RPMs have not come back up yet?

 

Dieseling is primarily caused by too much timing or an idle speed that is too high. Also, excessive age in the form of carbon deposits. I have even heard cases of the fan staying on acting much like a generator powering the ignition.

If the timing is off, hot spots in the combustion chamber can occur. These hot spots can get hot enough where they act like a mini spark plug and will actually ignite any unburnt fuel and air that happen to be in the chamber.

Obviously running rich will cause carbon deposits over time. Those carbon deposits have the same effect in ways of absorbing heat then acting as a spark plug.

With a carbureted car, if the throttle blades are open too far, aka - idle speed too high, enough fuel and air will still be fed into the engine to allow it to run on as it is. A throttle stop solenoid can be installed or adjust the idle speed (the more common fixture).

 

Yeah I've heard it's hot carbon deposites in the cylinder head igniting fuel. You may want to try running some seafoam or diesel fuel into a vacuum line leading to the intake (I use the PCV line for this job). Slowly pour it in while the car idles making sure it stays running and then really dump in the last portion of it to stall the car out. Let it sit for a few minutes and then start it and give a good spirited drive. This should clean out the carbon deposites and stop the dieseling.