after i shut the key off the car stays running until the carb runs dry. so i just keep on giving it gas untill it runs out. what is the prob?

 

Dieseling. It is actually detonating and turing the engine. Does it engine idle high? Was it overheating? Have you changed the carb settings? Changed gas type? Use carb cleaner?

It is usually a result of heat, octane, or fuel mixture. Give us some details, people will help!

 

Well its a 406 and its a brand new eldbrock 750 and i haven't touched the settings at all. I also have a Holley 600 and i tried that carb to and it still did it but it didn't run as long as the eld. did when i would shut it off. It has never over heated or anything like that i just got done buliding the motor. also another thing i noticed is that when i floor it, it acts like it wants to die but if i easy in to it, it wraps up just fine? and all the parts are new on the ignition brand new coil, the whole dis., plugs, wires everthing.

 

l think youre running a little rich, also what heat range are the plugs your using in?

 

i dont know for sure what the heat range on the plugs are but the a bosch platuim plugs. and so your saying if i make the carb a little leaner then it will hopefully stop when i shut the key off right? and where are those screws on the holley i know where they are on the eld. but not the Holley. thanks guys i will try this stuff tomarrow when i get the day off anyone else have any suggestions??

 

Does the engine continue to idle normally when you shut the key off? Or sputter and gasp?

 

it idles normal when i frist shut it off but then it starts to sputter when the fuel is about dry. i can usually wrap it up about 4000 rpm about 2-3 times before it starts to sputter then it dies.

 

Okay, if it's iding normally, then I'm guessing you have power on the coil when you shut the key off.

Did you just install the engine? If so, go over the wiring and check the coil for 12volts with the key off.

 

You have to set the carb for the engine. Buy there manual. It wont be that hard or time consuming if you know the dynamics involved. It sounds as if you are lean through the idle circute, and rich on your secondary. If that sounds like mumbo-jumbo, then do a little reading on carbs, they arent that complicated!!!

To set the idle mixture you need a vacuum gauge and an idle speed gauge plugged into the motor, and a screw driver to do the actual tuning. You can richin or lean untill you make the most vacuum at your designated idle speed. The secondary you will need to do at a drag strip (fun, fun, fun!) You buy either a set of metering rods (for an Edelbrock spread bore) or jets (for a Holley style carb.) Swap 'um until you make the most power (or trap speed)

Have Fun!!!