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Unread 07-10-2011, 08:30 PM   #1
jth0033
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1987 YJ Wrangler 
 
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Same old carb problems

Alrighty, well last month I decided to finally replace my pos carter with a newly rebuilt motorcraft carburetor offered from the guy on eBay. Had him deliver it with a new choke already installed for easy hookup. In the process I made sure to replace all of the vacuum lines. Also earlier this week I decided to do the Team Rush upgrade to help. Within the last few days though (even before the team rush) the Jeep has been running extremely rough under load. When coming to lights I am forced to shift it into neutral (automatic) to keep the idle up. Anyone have a clue what it might be???? Any help is greatly appreciated

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Unread 07-10-2011, 11:21 PM   #2
monkeyhouse
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Quote:
Originally Posted by jth0033 View Post
Alrighty, well last month I decided to finally replace my pos carter with a newly rebuilt motorcraft carburetor offered from the guy on eBay. Had him deliver it with a new choke already installed for easy hookup. In the process I made sure to replace all of the vacuum lines. Also earlier this week I decided to do the Team Rush upgrade to help. Within the last few days though (even before the team rush) the Jeep has been running extremely rough under load. When coming to lights I am forced to shift it into neutral (automatic) to keep the idle up. Anyone have a clue what it might be???? Any help is greatly appreciated
have you posed this question to the guy you bought it from? I understand he has great directions and support. I would start there.
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Unread 07-11-2011, 04:21 AM   #3
jth0033
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I have heard the same thing but figured I could get just as good or probably even better from my fellow jeepforum members
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Unread 07-11-2011, 05:16 PM   #4
jth0033
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Emailed the guy tonight and I'm going to check the choke wiring tomorrow. Also gonna check for any leaks at the carb base. Anyone have any other ideas?
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Unread 07-11-2011, 05:21 PM   #5
giggityjeeper
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vacuum leak somewhere is my guess
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Unread 07-11-2011, 05:23 PM   #6
superj
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me too
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Unread 07-11-2011, 06:32 PM   #7
4.7stroker
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Did you tune your idle mixture screws with a vacuum gauge?
Did you set your base timing to 8*btdc using a timing light?
Have you hooked your vacuum advance to Manifold vacuum NOT ported vacuum?

Dwayne
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Unread 07-11-2011, 06:50 PM   #8
jth0033
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Went out and checked tonight and couldn't find the culprit.

Dwyane:
I haven't checked the idle screws with a vacuum gauge.
Timing isn't set to 8* btdc, didn't know this needed to be done since I haven't nuttered
Here are some pictures provided by a fellow member as to how I have the carb set up. Does this seem to be correct?
underchoke.jpg   rear.jpg   front.jpg   driverside.jpg  
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Unread 07-11-2011, 08:31 PM   #9
4.7stroker
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You must nutter or the crippled computer will do what it likes to your timing.
Tune in this order.
At 750 rpm with vacuum advance disconected and plugged set your timing to 8*btdc.
Tune your idle mixture screws to maximum vacuum using a vacuum gauge. You must tune each screw the same amount. Wait 30 seconds between each adjustment. When you reach maximum vacuum screw each idle screw in 1/16 turn.
Hook your vacuum advance up to a Manifold vacuum source NOT ported vacuum.
You may now need to reset your idle rpms back to 750 rpm.
I always recheck I am at max vacuum - 1/16 turn and my timing is at 8* with vacuum disconected and plugged.
Without setting up right it will never run right and you will not be happy.
You can use a cheap vac gauge that is designed to be put in a gauge pod in the dash, just use some vac hose and you have a very useful tool. a halfway decent timing light costs $30, do not get one with an adjustable timing advance they will screw you up.

Dwayne
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Unread 07-11-2011, 08:38 PM   #10
superj
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that last bit, about the adjustable timing advance is so true. i have a craftsman with the adjustable and i am not sure its good. i have had it for 6 months and when i put it to zero and set the time to 8 degrees. i think its right so i set the light to 8 and check to see if the line is at zero, no go. its always at 3 or 4. makes me mad because its a heavy duty metal housed timing light.

so you can use any vacuum gauge to make the vacuum for the carb? i am going to look around and make one. i have not set mine up using your method because i don;t have a gauge but since its so easy, i will have ot get off my butt again and do it.
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Unread 07-12-2011, 07:15 AM   #11
jth0033
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Looks like I have some things to do then. After installing the carburetor I was nervous about doing the nutter since I didn't know if it would pass emissions and I have also never adjusted timing before, little hesitant about doing it seeing that I could really mess something up. Also have never set vacuum using a gauge, kinda learning everything as I go, and whereas its not difficult, I just need to find time since this is my DD.
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Unread 07-12-2011, 07:29 AM   #12
heyitslou
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I'm with you buddy my rig is my DD as well. It really limits the projects you can get into. Installing a Carb is far more difficult than the Nutter and setting the timing you will do just fine.
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Unread 07-12-2011, 01:28 PM   #13
jth0033
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Looks like I will be buying a timing light and vacuum gauge. Anyone know if I won't pass inspection/emissions with the timing set to 8*?
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Unread 07-12-2011, 02:01 PM   #14
monkeyhouse
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Quote:
Originally Posted by jth0033 View Post
Looks like I will be buying a timing light and vacuum gauge. Anyone know if I won't pass inspection/emissions with the timing set to 8*?
Timing isn't the issue. I would seriously find out what kind of emissions testing you will have to go through. In Maryland, a vehicle is considered "antique" after 20 years and you can get appropriate tags. With these tags, no inspection is required. I don't know about PA though. If you find that you cannot pass emissions testing, you may want to consider re-installing the Carter for testing. I have seen a few posts from some folks out west who do this.
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Unread 07-12-2011, 09:52 PM   #15
jth0033
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The carb sound pass I believe, dunno that the shop would seriously notice the difference, only that it looks new. I know nuttering probably won't pass emissions, thats why I never did it. I think to get antiques in PA it has to be 25 years but only 15 for classic. Thing is I think they have driving regulations on them, and this is my DD
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