weird idle

i have a 70 cj5 with a stock 225. It idles fine sitting in the driveway(750-800) but when i drive down the street and stop at the stop sign it idles very low(150-200) and i can tap the gas and it will go back to normal. I have replaced or rebuilt everything i can think of. It's about to kill me!!http://www.earlycj5.com/forums/images/smilies/icon_cry.gif

 

The idle screw shouldn't let it go any lower then what you set it at. Is it missing?

 

my idle screw was sloppy.
for a long time i couldnt figure out what was going on.
then once i was under the hood tinkering and i could see the idle screw turning by itself when i revved the engine.
locktite solved that.

 

That idle screw (the one on the throttle shaft) is supposed to have a pretty strong spring under it to hold it in position.

 

if it was the idle screw then it would stay at low idle. when i tap the gas it goes back to normal idle and will stay there till i stop again. it will do it the whole time you drive it.

 

Will the idle stumble if you screw the idle mixture screws in? Can you stall the engine by turning the idle stop screw so that the engine slows? Have you checked the fuel pump (is the float bowl full)?

 

I only see one screw on the side of the carb.

 

Timgr, the idle will drop if you screw in the two mixture screws. i will check and see if it will stall by turning the idles stop screw. it has a full bowl of gas (elec. fuel pump)

 

What is the condition of the throttle return spring?
It might be going bad on y'all.

Ed :tea:

 

IME a loose throttle shaft (worn carburetor body) will cause an erratic idle. Air leaking around the throttle plates changes the idle depending on the alignment of the plates with the bore. Though I've not seen the idle changes be quite so large or predictable as this - the idle would change from 600 to 800 to 750 depending on the whim of the carb.

 

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That's what I'm thinking. Can I buy just the throttle body plate or do I need to get a whole new carb?
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WTB a rochester carburetor throttle base plate. You have one or have any questions email me joeriscky@gmail.com
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I took some video to explain my first post
http://www.youtube.com/watch?v=LvpZ_HB2ok4
http://www.youtube.com/watch?v=yKVzJnWNOQw
Check out what the idle does when i come to a stop.

 

To check the throttle base for excessive wear, remove the throttle linkage. Engine at idle, move the throttle up-down and sideways without opening the throttle. If your idle doesnot change then you have no issue with the base assy. When you connect the throttle rod, be sure to set it along side the coupling and ball to make sure the throttle rod is adjusted to a point of just slightly beyond the ball when snapped into position. Make sure the choke cam is at full release and not holding the throttle open.

 

Thanks for the help. I'll check the base and linkage and see what happens.
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