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High idle at times- hitting throttle will sometimes help?

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I've not worked on a carb'd car before (just fuel injection). Just bought a 2002 with a fairly new engine (1998)... it's a '75. When I first start it, it'll idle at close to 2000 rpm. The previous owner suggested giving it gas once or twice while sitting still. She was right- it'll drop right down to around 800 (indicated) rpm.

But it'll continue to idle that high later on until the engine is really warm (even then, it idles high at times).

Any thoughts?

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first started, that's your automatic choke working. It's supposed to do that. Unlike a fuel injected engine where additional fuel is supplied when the engine's cold to keep it from stalling, a carbureted engine reduces the air flow to enrichen the mixture, and raises the idle speed to prevent stalling.

If it does this all the time, I'd check the accelerator linkage for binding. Check the pedal (there should be a little plastic bushing on the rod under the pedal, and the backside of the pedal should be lightly greased and not all dirty and cruddy). Also check the return spring on the firewall to make sure it's in place and isn't binding against the heater hose. If the latter, turn the spring around so it clears the hose. Finally check the carburetor throttle itself--disconnect from the linkage and see if it's binding at idle position. Thal'll require some lubrication.

cheers

mike

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Check the linkage where it connects from the pedal to the rod that goes to the carb (right in front of the firewall with hood open).

38linkage1-640.jpg

The pedal linkage has a threaded nut that spins up or down with a protruding nub that fits into the carb linkage.

If this is adjusted too far down it can cause the linkage to not come into contact with the idle stop screw causing higher revs. Sometimes blipping the throttle will make it return to where it should be, then, on your next throttle action, it sticks again.

If you adjust the nut up a little you should notice that by hand activating the linkage it consistently rests on the idle stop screw where it should be.

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Also check to see that the auto choke is working-

especially the electrics- they tend to lose conductance

and stay on all the time.

Easy to check.

t

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culpret. What, specifically can I do to check/test the elec choke? FWIW, it's a 38/38 and it's only a few years old.

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that's the most reliable way to check. Resistance measurements are sometimes misleading. Dunno what the current should be, but I'd guess more than 250 mA and less than 2 A.

Also, take the electric choke off so you can see the spiral spring. Verify that it moves when going from cold to hot.

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Thanks everyone. I drove the car again today... it seems to get stuck at two speeds- somewhere around 2000 rpm and somewhere around 1500 rpm. But a hard throttle blip will fix it.

I'll need to get some more grease.

This is a stupid question... I haven't gotten a manual for the car yet... where is the electric choke? Again, I've never worked on a carb'd car... in fact, my under-the-hood experiences have been mostly "plug and play" so far.

Thanks!

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