just a question on "rolling shut off"

[HAWAIISTANG66]

ok you know when you shut off your car, and your engine seems to want to keep going and spit and sputter, and defy what you are trying to do, (turn the vechicle off) but it wants to imbarrase you when you stop to go in somewhere, what the heck is that......

 

[rbohm]

8) it is actually, though improperly, called dieseling. what is happening is a fuel source interacts with a combustion source, and keeps the engine running. usually the idle speed is a bit high, along with the throttle plate being too far open, and that is coupled with a glowing carbon ember in the combustion chamber to create the problem. start by lowering the idle speed, by closing the throttle plate. if you need more idle speed, then bump the timing a couple of degrees. i would also run about 32oz of water through the system, SLOWLY to prevent hydrostatic lock, then run the car on the freeway for a bit. you can also use seafoam green run through the carb or the fuel tank.

 

[Anonymous]

I would check your distributor vacuum advance diaphram. If it is not working any longer, your timing at idle will be retarded and will not idle properly. Retarded timing also makes the engine run hotter. In order to compensate for a poor idle, folks commonly adjust the throttle plates open a bit more in order to raise the idle speed.

Disconnect the vacuum line at the distributor and plug the line and or hold your finger over the end of it. The engine should slow down and run rougher if the vacuum cannister is working. If your distributor is hooked up with a hose instead of a steel line, conect a rubber line to the vacuum diaphram and suck on the diaphram to see if it holds vacuum. If not, you need to replace the vac motor. With the engine running, if you suck on the vac motor, the engine should speed up if the vac advance is functioning properly.

As a side note if you have replaced the original carb and you still have the original load-a-matic distributor, there is probably no provision for the spark control valve and the distributor will not function properly and should be replaced with a later style distributor.
Doug

 

[Anonymous]

possible remedies
1--higher octane fuel, low octane ignites easier and burns faster. The higher the octane the slower it burns.
2--colder plugs, hot/cold plug denotes the temp of the plug itself not the spark. heat+compression+fuel= detonation-
3--timing off EITHER way--too much advance increases piston crown temp too little heats up exhaust valves.
4-- use something burn off carbon deposites from cumbustion chamber.
5--if you have a tank full of crappy low octane fuel Shut it off in Drive if auto or ease the clutch out in 1st when shutting it down till you get rid of the crap gas.
6--tune er up, choke or idle or even idle mix provided extra fuel.
Heat+compression+fuel = ignition--that's why they call it dieseling.Compression makes heat. Diesel have 17-1 or more compression and unless you have a lot of carbon you have like half that. Remove 1 element from the equasion and you are home free.