Tweaking weber carb? - JeepForum.com

 
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post #1 of 4 Old 06-27-2012, 08:15 PM Thread Starter
poesdad
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Tweaking weber carb?

I hope this is in the right section.

I have a rebuilt 4.2L 258 in my 1990 wrangler and purchased a weber carb for it a while back. Since I have had the carb, I have had problems with it stalling at stop signs or whenever I slow to a stop. I remember back when I had the stock carb, I could adjust the jet screws (? Not sure if that's what they are called) and it would change the idle.

Is there any easy way to do this on the weber carbs?

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post #2 of 4 Old 06-28-2012, 08:01 PM
90DesertTanYJ
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I just inherited a Weber on my 90 4.2. You need to go to RedLine.com, a Weber distributor and check out the site for instructions. IIRC the idle mix screw should be 2 full turns from closed to start with. Then you experiment screwing it out a bit to see when it starts running rough. If its rough to begin with, turn it back in up to 1 full turn to try and find the sweet spot where the truck is running OK. When I got mine, the IM screw was 4 full turns out, running so rich you couldnt stand the unburned gas smell out the back. I rolled it back to 2 turns out, then rolled it back 1 to 1 full turn out from closed and its running fine and no smell except the little oil burning. The site also says that if you have to turn it in/out more than 1 turn, you may need to buy different jets.

Be careful when you turn the IM screw closed, dont overtighten it or you will kill your carb.
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post #3 of 4 Old 07-04-2012, 11:28 PM Thread Starter
poesdad
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Quote:
Originally Posted by 90DesertTanYJ View Post
I just inherited a Weber on my 90 4.2. You need to go to RedLine.com, a Weber distributor and check out the site for instructions. IIRC the idle mix screw should be 2 full turns from closed to start with. Then you experiment screwing it out a bit to see when it starts running rough. If its rough to begin with, turn it back in up to 1 full turn to try and find the sweet spot where the truck is running OK. When I got mine, the IM screw was 4 full turns out, running so rich you couldnt stand the unburned gas smell out the back. I rolled it back to 2 turns out, then rolled it back 1 to 1 full turn out from closed and its running fine and no smell except the little oil burning. The site also says that if you have to turn it in/out more than 1 turn, you may need to buy different jets.

Be careful when you turn the IM screw closed, dont overtighten it or you will kill your carb.
thank you,

Now it dies every time I put the clutch down. really sucks.. I can't even drive it now..
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post #4 of 4 Old 07-04-2012, 11:35 PM Thread Starter
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