replacing carb - Right CFM?
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
replacing carb - Right CFM?
>I can't get the remanufactured carb to idle below 800 rpm's
>even with every thing idle speed screw and choke screw
>backed out. I am trying to check for vacuum leaks and will
>even retry the carb that I took off.
Richard, I've seen this problem with remanufactured carbs. The problem is the throttle plates are not centered in the bores. Instead they are off a little and jam up before they are fully closed. With the carb. off, shine a light through the top while looking at the bottom. There should be an equal amount of light all around the plates when they are fully seated. Make sure the idle speed screw is all the way out when checking. To fix it, you crack loose the screws holding the throttle plates (don't take them out) and then close the throttle while tapping on the plates, they will find their centers and seat in the bores. When they are seated, pull back and forth on the throttle shaft to make sure it is centered and not favoring one side or the other. Now tighten the screws holding the plates. You should be able to get it to idle below 500 rpm now. Hope this helps.
Barry
>even with every thing idle speed screw and choke screw
>backed out. I am trying to check for vacuum leaks and will
>even retry the carb that I took off.
Richard, I've seen this problem with remanufactured carbs. The problem is the throttle plates are not centered in the bores. Instead they are off a little and jam up before they are fully closed. With the carb. off, shine a light through the top while looking at the bottom. There should be an equal amount of light all around the plates when they are fully seated. Make sure the idle speed screw is all the way out when checking. To fix it, you crack loose the screws holding the throttle plates (don't take them out) and then close the throttle while tapping on the plates, they will find their centers and seat in the bores. When they are seated, pull back and forth on the throttle shaft to make sure it is centered and not favoring one side or the other. Now tighten the screws holding the plates. You should be able to get it to idle below 500 rpm now. Hope this helps.
Barry
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Senior User
Joined: Sep 2002
Posts: 142
Likes: 0
From: Cary NC USA
replacing carb - Right CFM?
Thanks Barry,
I sent the remanufactured carb back. Made some repairs, not rebuild, such as locking in kick down lever and reworking choke cam, then reinstalled the " original". Replacing the spacer to maniford gasket may have gotten rid of a vaccum leak which I was also told would increase idle.
Seem to be in good running condition for for now. ( I maye have to make a new thicker choke idle cam because of different length shafts in the throttle and the choke mounting. Right now I have a cap screw installed in reverse at choke so that contact is made with the head to control idle)
Richard
I sent the remanufactured carb back. Made some repairs, not rebuild, such as locking in kick down lever and reworking choke cam, then reinstalled the " original". Replacing the spacer to maniford gasket may have gotten rid of a vaccum leak which I was also told would increase idle.
Seem to be in good running condition for for now. ( I maye have to make a new thicker choke idle cam because of different length shafts in the throttle and the choke mounting. Right now I have a cap screw installed in reverse at choke so that contact is made with the head to control idle)
Richard
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