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ZS Carb Problem

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kyreb1862

kyreb1862

Jedi Knight
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I have rebuilt my ZS carb, cleaned and lubed the choke mechanism and tried tuning the carb. No matter what I have tried it runs to rich. The thing is driving me nuts. Would setting the float to high cause it to run rich? Help!! /ubbthreads/images/graemlins/confused.gif
 
yup, errrr... no... setting the float too high would have the float closing the valve too soon. However, setting the float too low would result in the carb always running too rich.

Ya have to remember that the float height measured in a ZS carb is when it closes the valve. A larger height closes sooner, and a smaller height closes later. Mainly because of the way the float is mounted in the carb body. Where most floats are attached to the float bowl, the ZS's float is attached to the float bowl lid.

I can't remember the height it should be set to right off hand, and my manuals are at home. If no one comes up with the proper float height before I get home for work I'll be sure to look it up.

In an attempt to avoid pulling the carb off the car to reset the float, have you checked to make sure the mixture needle is actually moving when you turn the fuel mixture screw? This should be as easy as taking the dash pot cover off, removing the piston, turning the fuel mixture screw, and watching the needle for movement. If it doesn't move in and out of the piston body then you might have the set screw set too tight (but that shouldn't be possible).

Another thing that can cause a ZS to always be too rich is if the needle isn't being held in the needle assembly body properly. To check this, remove the piston from the carb, and remove the needle assembly from the piston. The needle should be spring loaded in a brass body and a pin at the top to prevent the needle from popping out and riding too high. If there's no pin holding the needle in, the needle will ALWAYS ride too high too allow for proper fuel mixture adjustment.

I ran circles around that last one with my car when I first got it. Until I found the problem that is. /ubbthreads/images/graemlins/smirk.gif The upside that was, once I found that tiny little problem, I was able to fabricate a new retaining pin using a straight pin from a sewing kit.
 
Ever the resourceful Marine!

Another possibility is the "automagic" choke: The actuator lever may not be in the square end of the bi-metal spring... just a thought.
 
Ok, bi-metal spring is in place on the actuator lever. If the fuel level is to high in the float bowl will it run rich? That is the only thing In haven't checked today. I have been trying to avoid that.
 
Hah, John. That's about the first thing to check.
 
Phil's post with picture (in the above link) is exactly what I was referring to when I mentioned fabricating a retaining pin from a sewing kit straight pin... /ubbthreads/images/graemlins/thumbsup.gif

You're fuel mixture needle should look like Phils if it's together right!
 
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Hah, John. That's about the first thing to check.

[/ QUOTE ]

You were right Jack. I tore down the carb reset the float and checked all the adjustments. Filled up the cooling system and put in new plugs. Took "Molly" for a short drive and then checked the plugs. Plugs are now brown. Think I finally got it. Thanks to everyone that offered advice. /ubbthreads/images/graemlins/thumbsup.gif
 
Glad ya got it sorted, John.

Are the plugs a "Sudbury" brown or "Cadbury"? /ubbthreads/images/graemlins/jester.gif
 
More of a Cadbury brown I believe. /ubbthreads/images/graemlins/jester.gif
 
You're there, dude! That's the right one. /ubbthreads/images/graemlins/wink.gif
 
personally I prefer Guiness suds brown more... /ubbthreads/images/graemlins/wink.gif
 
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