1964 Imperial engine having problems running at low RPM

64 Imp Crown

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My 64' Imperial is having a problem staying running at a low rpm. Once I'm above 2 or 3 mph it runs perfect. All parts are orginal except the distributor and now the voltage regulator. I had the battery and alternator tested and are good. I put a new condenser in the distributor and a new voltage regulator on. I'm still having the same problem. I can't figure out what's wrong. Any help would be greatly appreciated.
 
This could be several things. If the engine runs smoothly every where except at idle, you problem is probably not electrical. One of the idle mixture screws at the base of the carb may be improperly adjusted or plugged. The FSM gives instructions on how to adjust the carb, both for mixture settings and base idle settings. Download the FSM at www.mymopar.com it is free and you will find it in the Tools/Reference section. Adjust the carb. If it still will not idle, you probably will need to rebuild the carb. Modern moonshine blend gasolines are very hard on vintage carbs, especially if the car has sat a lot between uses. Plan on ordering floats if you determine that the carb needs a rebuild. You car should have an AFB carb and they are not difficult to rebuild. Be sure to get a can of Brake Kleen and use the want to flush out all the fuel passages.

Dave
 
This could be several things. If the engine runs smoothly every where except at idle, you problem is probably not electrical. One of the idle mixture screws at the base of the carb may be improperly adjusted or plugged. The FSM gives instructions on how to adjust the carb, both for mixture settings and base idle settings. Download the FSM at www.mymopar.com it is free and you will find it in the Tools/Reference section. Adjust the carb. If it still will not idle, you probably will need to rebuild the carb. Modern moonshine blend gasolines are very hard on vintage carbs, especially if the car has sat a lot between uses. Plan on ordering floats if you determine that the carb needs a rebuild. You car should have an AFB carb and they are not difficult to rebuild. Be sure to get a can of Brake Kleen and use the want to flush out all the fuel passages.

Dave
Carb has already been rebuilt along with new gaskets and seals in the motor and transmission. It will idol and drive fine above 4mph. The dash lights will dim and brighten up full time
 
Carb has already been rebuilt along with new gaskets and seals in the motor and transmission. It will idol and drive fine above 4mph. The dash lights will dim and brighten up full time

If it has been rebuilt, then it probably just needs to be properly adjusted. Lights dimming at low RPM is normal. Try turning the base idle screw in about 1/2 turn. This should raise the idle slightly to where the engine will stay running.

Dave
 
Is this not wanting to idle in gear, with brakes holding car at a stop? Or in neutral?
How long have you had the car, is it a new problem or ???
Is the problem different when the engine is cold or warm?
If not carb related, perhaps you need a little more advance in your base ign timing?
 
It’s hard to diagnose without more information. It can be anything from carb adjustments, vacuum leaks, electrical, timing and so on. What rpm is it at during idle, in gear or not? What is your timing set at? Are the vacuum hoses in good condition and are they connected properly.
Sometimes it helps if you can post a video of it running so we can see it and hear it.
Also did you do anything more to it than you indicated above.
If you can provide this we should be able to help.
 
If it has been rebuilt, then it probably just needs to be properly adjusted. Lights dimming at low RPM is normal. Try turning the base idle screw in about 1/2 turn. This should raise the idle slightly to where the engine will stay running.

Dave
Lights dimming is not just at low rpms. Everything was running perfectly put about 500 miles on it sence doing the gaskets and carb rebuild. I drove it two weeks ago everything perfect. Then went to drive it in to work last week when it started acting up. With the car in gear anything under 4mph the car wants to die out unless I keep my foot on the gas or put it in neutral. Above 4mph it drive perfect. I dont know the exact rpms cause it doesn't have a tach. When we did the carb we put all new vac lines. We set the timing at around 15° instead of 12°.
 
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Lights dimming is not just at low rpms. Everything was running perfectly put about 500 miles on it sence doing the gaskets and carb rebuild. I drove it two weeks ago everything perfect. Then went to drive it in to work last week when it started acting up. With the car in gear anything under 4mph the car wants to die out unless I keep my foot on the gas or put it in neutral. Above 4mph it drive perfect. I dont know the exact rpms cause it doesn't have a tach. When we did the carb we put all new vac lines. We set the timing at around 15° instead of 12°.
What gaskets did you replace. Who rebuilt the carb. It sounds like it is either very lean or flooding. At idle look down the throat of the carb and see if gas is dripping down. If. It cup your hand over top of the car and see if it settles down.
 
What gaskets did you replace. Who rebuilt the carb. It sounds like it is either very lean or flooding. At idle look down the throat of the carb and see if gas is dripping down. If. It cup your hand over top of the car and see if it settles down.
I dont believe its flooding. It literally sounds like I have a massive cam in it and it would chug a couple 3 or 4 times and die in gear. In neutral or park or driving above 3 to 4 mph it is fine.
 
Yes do what I suggested put your hand over the carb to choke off some air. It it runs better you know what to do. The other thing you can do is get a can of carb spray and spray it in. Also spray the intake manifold where it meets the head and any place that vacuum is. If you have a brake booster do you hear a hissing noise.
 
Yes do what I suggested put your hand over the carb to choke off some air. It it runs better you know what to do. The other thing you can do is get a can of carb spray and spray it in. Also spray the intake manifold where it meets the head and any place that vacuum is. If you have a brake booster do you hear a hissing noise.
I didn't hear anything from the break booster. But now I'm having a hard time getting it started. That just started after I put the alternator back on. I'm having problems finding all the vacuum lines.
 
Before any of us can help you need to give us more information like the questions I asked before. Usually if you have a problem after doing something, like a carb or gaskets, that would be a good place to start.
 
Before any of us can help you need to give us more information like the questions I asked before. Usually if you have a problem after doing something, like a carb or gaskets, that would be a good place to start.
When I had the gaskets and carb done and I believe most of the vacuum lines were replaced. I drove it over 500 miles. 2 1/2 weeks when I got done driving it and parked it. Hopped in a week later and went to drive it when all this started.
 
I would take it back to the person who did the carb.
Not to sound like a noob. But I had drove alot of miles with no problem and it was like a switch flipped. The carb did get a second rebuild. We had a problem with the distributor and thought the carb might be it so they took it apart and redid it.
 
Just to show the care we took in rebuilding the carb. It is easy to tell the before and after.
IMG_0004.jpg
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