Default Scary High Idle After Carb Rebuild 

Old 01-15-2020, 11:13 PM   #1
Spduffee is offline
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The little ol lady who swallowed the fly - I replaced the bushings to better the ride. Removed the tank to remove the rear shackle. Replaced the tank after seeing the cancer. Cleaned the lines because of the tank. Rebuilt the carb (Carter AFB 9-series) because of the lines. Perhaps I'll die....
It's all back together and it starts. But holy crap, it almost launched to Mars it was revving so high! Scared the bejeebisses out of me. I can't leave it running to adjust, it's running that high.
The throttle cable and return spring are back where they were. I did take the electric choke apart and may not have put it back correctly. The floats (new brassies) were adjusted per plan (5/16 and 15/16). I have rebuilt a couple carbs and this never happened.
Any advice?
Thanks,
Shawn

 

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Default Re: Scary High Idle After Carb Rebuild 

Old 01-15-2020, 11:32 PM   #2
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There is a separate screw behind the choke that may be screwed down to far, that is for the fast idle when the choke is on. I would check that screw and back it off first and see if that was the problem.

Also to check - make sure the secondaries are closing all the way. There should be a stop screw on the choke side of the carb on the underside that is a 'stop' when the butterflies close. Make sure this is not screwed down too far or it will hold the butterflies open.

those would be the first two checks on my list.

And let us know after you check those.
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Default Re: Scary High Idle After Carb Rebuild 

Old 01-15-2020, 11:34 PM   #3
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And just for giggles, my next thought would be an open vacuum line, so check all of those.
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Default Re: Scary High Idle After Carb Rebuild 

Old 01-15-2020, 11:47 PM   #4
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Ok thanks for the reply, I will try those suggestions. I didn't really mess with any adjustments except for the two idle mixture screws. I turned those in, then back out to where they were before, but maybe too far? I did change the plumbing from the left port to distributor to the right port to distributor, based on a suggestion. I also just remembered my vapor canister is still sitting on my bench, but it is fubar anyway. I think all other vac hoses are correct, but maybe not.

 

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Default Re: Scary High Idle After Carb Rebuild 

Old 01-16-2020, 12:29 AM   #5
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When in doubt about the vacuum lines, just plug everything and see what happens.
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Default Re: Scary High Idle After Carb Rebuild 

Old 01-16-2020, 08:11 PM   #6
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Sustained high rpms would lead me to throttle valve not closing correctly, primary or secondary circuits. My two cents.
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Default Re: Scary High Idle After Carb Rebuild 

Old 01-17-2020, 01:57 AM   #7
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Well, it warmed up a few degrees here and the kids were busy, so I popped out to see what condition my condition was in. I am ashamed to say it, almost, but I had hooked the throttle up like it should be, not how it was. I had the cable fed through the mounting post and after disconnecting the cable and tapping forward on the linkage, it fell forward to where it came to rest, about 3/4" further than it was. It seems the PO bypassed the post and this gave it more slack? I'll investigate that all tomorrow. But I did start it, ran well, but with raw headers I can't run it too long and it's hard to hear what's good or bad.
Now to figure out why the cable seems too short....
Thanks for all the input, very much appreciated!

 

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Default Re: Scary High Idle After Carb Rebuild 

Old 01-17-2020, 07:29 AM   #8
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My '79 with stock throttle cable had a lot of linkage with it, not just a cable.

Does yours have the stock cable? An aftermarket cable like some of us have done may be a good move too.
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Default Re: Scary High Idle After Carb Rebuild 

Old 01-17-2020, 11:05 AM   #9
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I'm not sure if the photo is going to show or not that I uploaded. My 4yo could manage better than me....
I assume the cable is stock because my '86 Wagoneer has a 2150 and the linkage sits back further. Of all the things I photgraphed before taking apart, I missed taking a photo of the previous setup.
Is there any adjustment possible at the pedal?
If I look for a new cable that is a titch longer, do I search by length?
Thank you again!
Shawn
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Default Re: Scary High Idle After Carb Rebuild 

Old 01-17-2020, 05:45 PM   #10
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Quote:
Originally Posted by Spduffee View Post
I'm not sure if the photo is going to show or not that I uploaded. My 4yo could manage better than me....

I assume the cable is stock because my '86 Wagoneer has a 2150 and the linkage sits back further. Of all the things I photgraphed before taking apart, I missed taking a photo of the previous setup.

Is there any adjustment possible at the pedal?

If I look for a new cable that is a titch longer, do I search by length?

Thank you again!

Shawn
Lokar makes a universal throttle cable you can cut to length. I ordered the longest one then cut to fit and it worked great.

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