truck problems?

Question

ok i have a old chevy with a edelbrock carb and when i turn my motor off it begins to shake and acts like it is still trying to run, when it starts doing this i turn my key back on and the truck sarts right back on, i believe its the carb, am i right, and if so how do i fix it,plz details

Answer 1

Your timeing is to far advanced. Get a Timing light and set it at 34 degrees total advance with about 12-14 initial and your motor will run excellent. But you may need some new plugs too since they could be fouled.

Answer 2

this is called dieseling. i have been told that it is caused by the fuel mixture being too rich which in turn causes carbon buildup on the pistons. here is tom and ray's opinion:
Ray: 99 percent of the time, dieseling is caused by an idle speed that's set too high. The engine is turning so fast that it simply has too much angular momentum, and can't stop right away. So when you turn off the key, the engine keeps turning

Tom: And because it's still turning, fuel gets sucked in from the carburetor. And since the engine is still hot, some of that fuel gets combusted. So the engine continues to run (albeit poorly) for a few seconds after you shut off the ignition.

Ray: And since heat plays a crucial role in dieseling, anything that makes the engine run too hot is bound to make your problem worse. So in addition to having your mechanic check the idle speed, you should also have him check the timing, the cooling system, or anything else that could lead to overheating.
http://www.cartalk.com/content/columns/Archive/2001/July/02.html
check out this answer too:

Answer 3

That would be dieseling!

dieseling (′dē·zəl·iŋ)

(mechanical engineering) Explosions of mixtures of air and lubricating oil in the compression chambers or in other parts of the air system of a compressor. Continuation of running by a gasoline spark-ignition engine after the ignition is turned off. Also known as run-on.

Dieseling or engine run-on is a condition which can occur in sparkplug internal combustion engines whereby the engine keeps running for a short period after being turned off, due to fuel igniting without spark. Dieseling is so-named because this is essentially how diesel engines operate (without spark).

An automobile engine that is dieseling will typically splutter then gradually stop rather than continue running as if the engine was not switched off at all — the latter would usually indicate an electrical fault.


Potential causes
This condition can occur for a multitude of reasons:

Built-up carbon in the ignition chamber can glow red after the engine is off, providing a mechanism for sparking unburnt fuel. Such a thing can happen when the engine runs very rich, depositing unspent fuel and particles on the pistons and valves. Similarly, non-smooth metal regions within the piston chamber can cause this same problem, since they can glow red. It has also been suggested that an improperly rated sparkplug can retain heat and cause the same problem.
A carburetor that does not close entirely can contribute to running once the engine is off, since the extra fuel and oxygen mixture can combust easily in the warm piston chamber. Similarly, hot vaporized oil gases from the engine crankcase can provide ample fuel for dieseling.

Incorrect timing.

An engine that runs too hot or too lean may produce an environment conducive to allowing unspent fuel to combust.
An idle speed that is too fast can leave the engine with too much angular momentum upon shutdown, raising the chances that the engine can turnover and combust more fuel and lock itself into a cycle of continuous running.

Potential fixes

Items similar to carburetor cleaners and carbon cleaners have been suggested as partial remedies for attempting to clean the piston chambers and valves of engines that run too rich.

For those engines that have sharp metallic edges, it has been noted that poorly milled heads and blocks can contribute to this problem, so having the rough spots smoothed may help.

For those engines that run too hot or too lean, verify that all mechanisms in place to cool the engine properly function as they should. Replace the thermostat if necessary. Clean the radiator. Verify that all auxiliary fans engage at their proper temperatures, and ensure that the thermostatic sensors on belt driven fans engage as necessary.

In the case that there is too much angular momentum, lower the idle speed if possible.

Answer 4

This condition is known as "Dieseling" and is caused by ignition of the gas that is still being pumped in by the fuel pump. In the old trucks and cars the fuel pump was driven by the cam shaft. It can be caused by being out of timing and also the old, old trucks ran on leaded gasoline and now you can't by it so the engine has to be readjusted. You might also try using a different gas or you may have to upgrade to a more expensive fuel, like a higher octane.

Answer 5

it could be the carb (too lean/ hot), timing too advanced/ hot) carbon deposits in the combution chamber (hot enough) or an off idle solenoid that is stuck in the on position.

Answer 6

It's your timing...get a timing light and set the timing and it will cure it.

Answer 7

nope it's in the distributor and ignition system