Bad idle on Carter BBD finally solved!! -
  • 2 Post By only in a jeep cj
  • 1 Post By LumpyGrits
LinkBack Thread Tools
post #1 of 8 Old 09-06-2019, 04:57 PM Thread Starter
only in a jeep cj
Registered User
1986 CJ7 
Join Date: Jun 2001
Location: Mobile
Posts: 6,069
Bad idle on Carter BBD finally solved!!

I never understood why people are so fast to replace the Carter BBD that came on the later CJ. I’ve been running one in some form or another on all my late CJ‘s for the last 27 years. They are very easy to rebuild and set up. Disclaimer, I am at sea level.

Anyway, mine went from running great to all of a sudden having an erratic idle, and just feeling really weird in between shifts or when there was no load on the system. Some days it was worse than others and there was no smoothness as before.

So I figured the idle tubes were gummed up or something of that nature. I rebuilt the carb just as I always have and there was no change afterward. The more and more it fiddled with it, the more I concluded it was acting like a vacuum leak. I messed with all of the hoses such as the vacuum advance, the power brake booster, choke plate diaphragm, PCV hose, etc. and got nothing. I pulled spark plugs, checked resistance in the plug wires, swapped the ignition module out, checked dist cap/button/ contacts, timing, sprayed the seals checking for idle change, etc....still nothing. . I drove this thing for three months, the whole time about to pull my hair out.

So I pull the carburetor off one more time to go back through it and check again. As I pulled it off of the mounting studs I looked down at the plastic spacer block between it and the manifold and thought to myself that I don’t believe I removed that spacer and checked it last time. The picture shows what I found under the spacer. Two new gaskets later, I have a steady idle and a smooth running engine.

So for those who might have a vacuum leak or an idle issue, don’t forget to check everywhere ....even the stuff that is hidden out of sight.

Attached Thumbnails
John Strenk and 258 like this.

1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon
only in a jeep cj is offline  
Sponsored Links
post #2 of 8 Old 09-11-2019, 12:40 PM
Registered User
Join Date: Jul 2019
Posts: 84
I think that is the problems with Carter- when they have an issue, their hard to find out what the problem is. Don't get me wrong, the Carter Carb works great when it's dialed in. It's getting it dialed in, or finding the problem that gives it a bad wrap.

Spent last weekend doing a Carter BBD rebuild (well I did not do it, my son along with my father did it on the work bench). Got a nice kit from Mike's Carberator and a new choke spring so for $50 figured it's worth rebuilding the carb. As well as getting my son some first hand knowledge about how a carburetor works.

After the rebuild by dad, who was a mechanic/ wrench turner for years back in the 60-70's and has over 50yrs in the auto service industry, was telling my son that was not a easy carb to rebuild. I certainly was not going to argue with him about it.
mc190 is offline  
post #3 of 8 Old 09-11-2019, 08:59 PM
Web Wheeler
BagusJeep's Avatar
1981 CJ7 
Join Date: Jul 2009
Location: Bali
Posts: 7,246
I struggled for years with mine until the accelerator plunger broke up. I got a clone from fleabay for one of my jeeps (which is crap) but it is standing instead of teh BBD which si now scheduled for a rebuild. the Weber 38 is better IMHO.

BagusJeep lives in Bali.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
BagusJeep is offline  
post #4 of 8 Old 09-11-2019, 09:21 PM
Registered User
brianscoob's Avatar
1976 CJ7 
Join Date: Dec 2013
Location: Donald
Posts: 45
I took on the Carter carb years ago and I just couldn't get it to run properly but it mind I wasn't going to be defeated, until I was. I put a Weber on and with hardly making any adjustments the engine just purred. Back them it was a huge expense to put a Weber on but I saved up the money and it was well worth it. Years later I rebuilt the Carter but I never put it back on. I think MC190 is right in that if you have the Carter dialed in you'll have no problems but it's a PITA if you don't. Crazy because I don't remember what I did with the Carter I took off and rebuilt?? It's been over 25 years probably.
brianscoob is offline  
post #5 of 8 Old 09-12-2019, 04:54 AM
John Strenk
John Strenk's Avatar
1976 CJ5 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 19,685
We are still talking the difference of a new clean carb vs a home rebuilt worn out carb.

I put on a new BBD from National carb and I haven't had to touch it in 5 years now.

Starts right up with a twist of the key. Runs strong.

I think I counted some 30 openings in the carb and if only one of them gets clogged, it will cause problems.
Soaking them in carb cleaner after the passages get clogged doesn't usually work.
And then there is the wear around the throttle shafts to worry about.

I also wonder of the pump gas we are putting into our jeeps is worse than what these carbs were originally designed for.
I know my old lawn equipment runs great on non-alcohol gasoline. My jeep will probably run better also but it's too expensive to burn there.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

I drive a Prius to save money and buy more Jeep Parts....
John Strenk is online now  
post #6 of 8 Old 09-13-2019, 08:09 PM
Registered User
1985 CJ7 
Join Date: Jul 2010
Location: The Mojave Desert - Palmdale, Ca. U.S.A.
Posts: 7,096

Lots of good info here--

I for one like the Carter, and it's the only carb allowed for Ca. SMOG on our late model CJ's w/4.2L.

258 likes this.

Have'n you along, is like loose'n 2 good men
LumpyGrits is offline  
post #7 of 8 Old 09-13-2019, 08:37 PM
Registered User
1985 CJ7 
Join Date: May 2013
Location: SP
Posts: 2,116
Interesting! . . . and good to know!

I have actually been dealing with the same issue and it has been driving me crazy. The carburetor was replaced at previous smog; one year ago, but it never ran like the old OEM Carter BBD. After that OEM one was rebuild right, it ran smooth. This exchanged one never has? I have wondered if they gave me a knock-off but was too exhausted at the time to argue with the shop. The smog stuff I went through just wore me out at that time. I did get angry at the shop for replacing it rather that sending it to get properly rebuilt. Oh well.

Anyway, today I actually started tracing hoses, cleaning plugs, cap, etc. trying to look for my erratic idle issue. After everything I did, it runs better but not 100%. I will definitely take a look at the Carter base plate this coming week. I forgot what a smooth ride the Carter can produce, lol. . . . Thanks "only in a jeep cj" for that tip.

"LumpyGrits", you are 100% correct about CA only allowing the Carter. I'm still scratching my head about that!!!
258 is offline  
post #8 of 8 Old 09-14-2019, 06:05 AM
Registered User
ddawg16's Avatar
1984 CJ7 
Join Date: Oct 2018
Location: South Bay
Posts: 685
I kept mine running well for about 15 years (bought the jeep in 94). My biggest issues were vac leaks in hoses and the charcoal canister. Oh, and the worn throttle plate shaft.

But.....going to a fuel injected SBC? No going back.

It's so nice to start on a steep hill....and not be flooded.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ddawg16 is offline  

Quick Reply

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome