Engine will not shut off?

[LastLeg]

A-4 1970 Vintage, new wires,Alternator, plugs and rotor. I also purchased a high voltage coil from a local NAPA.

I just installed a new Alternator purchased from (MM) started right up getting the amps and charging, great stuff.

However for some reason only when the engine runs for about 5 minutes when I shut the ignition off the engine continues to run. Interestingly the engine also changes pitch, the only way to kill it at this point is to pull the choke. Is this normal. As I am brand new to the A-4

[Tim]

The same thing happened to me when I installed a new alternator. I has accidentally connected the coil to an alternator output instead of the exciter connection which kept the coil energized even with the ignition switch off. Try disconnecting the exciter wire and see if the problem stops.

[LastLeg]

I will try this today, where is the exiter, I used the documentation and it was quite clear.

Thanks for the reply!

[Buck]

"where is the exiter"

The connections on the back of an alternator can be confusing, because the names vary between manufacturers. The exciter is sometimes called "field", and sometimes called "light". On the back of my trusty Delco, the exciter connection is labelled "1". Whatever the label, the exciter lead usually goes from the alternator to the + side of the spark coil.

It sounds like you made all your connections correctly. Connecting the exciter connection directly to the positive side of the coil can sometimes cause the engine to run on. With the ignition off, the spinning rotor can generate enough voltage to energize the coil. One way to check this is to pull the exciter connection off the coil or off the alternator while the engine is running and seeing if this causes your engine to stop. If this is your problem, you can prevent current from flowing "backwards" from alternator to coil by installing a diode in the line.

If it's the exciter connection that causing your engine to run on, the simplest and least elegant way to solve the problem is to just yank the exciter connection. The drawback of removing the exciter connection is that you'll have to rev your engine to about 2k to get your alternator to turn on.