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84 Ranger

I have an '84 Ford Ranger that I have had many years, and I can’t bear to part with it. It has 150K miles, new engine at 90K. Ever since the new engine was installed I have had some trouble with the idle. Have put in a carb kit, several different mechanics have adjusted, etc. The vehicle runs great going down the road at most any steady speed, just doesn’t idle well, and eventually will die if left. The last mechanic who worked on this, after giving the engine a complete tune-up, (plugs, plug wires, distributor cap, rotor, etc…) said he thinks the idle problem is due to the fact that the emission control equipment was disconnected when the engine was changed. What do you think of his diagnosis, and if you agree do you have a better solution than he did, which was to just get used to it?

There’s a difference between putting a kit in a carburetor and overhauling a carburetor.
The latter means soaking the completely diassembled carburetor for at least an hour followed by washing it all out thoroughly with water and blowing it all out with compressed air.
Which one was done?

The problem could very well be in the carburetor, a vacuum leak, ignition timing way off, etc. There’s just no way of knowing from here what was or was not done as to the carb., vacuum lines, etc.
A wild guess points to a carburetor problem that either has a clogged idle port or is loading up, meaning that it’s running too rich. The latter could be due to the idle mix screws being too far out, a leaking power valve, and in a few rare cases this can be due to a porous carburetor casting which is allowing gasoline to leak internally.

I’ve seen a couple of Ford carburetors with the casting problem. The only way of determining this is to remove the carburetor, fill the float bowl with gas, and then sit and wait to see if the bottom of the carb starts getting wet with fuel.
I do not agree with the get used to it diagnosis.

There is a vacuum (mixture control) solenoid attached to the carburetor which becomes a vacuum leak when the emission system is not operating correctly. With the engine idling and the solenoid removed experimenting with blocking selective ports can often improve the idle. Those early efforts at computer control of the air fuel mixture were never very effective and are not economically restorable.