Jump to content

Recommended Posts

Let me start off by saying I am a complete novice when it comes to mechanics. I figured the best way to learn is to jump in and start trying myself. My Jeep was running great the last time it was driven, but it has sat for about a year and now will not start.

 

Not getting fuel, I read online about a quick fix for idle problems by clearing the venturi tubes. While following the directions, I took off the air horn to get to the venturi cluster. I was holding the air horn in one hand and looking at another part in the other hand, an O-ring gasket (approximately 1/4 inch) popped off the air horn and landed on my wrist.

 

I have no idea where it popped off of and have not been able to find it on exploded view diagrams on the rebuild kit. The ring is in the kit but I cannot find it in the diagram. 

Any idea where this ring goes?  What do you think the odds of a beginner being able to clean and rebuild this carburetor correctly?

Thanks for any help...

Link to comment
Share on other sites

  • Administrators

ScramblingMan, welcome to the forums!  Very pleased with your participation, and the whole aim with these forums is to bring members up the learning curve by sharing information.

 

First, with your Carter BBD two-barrel, you're in luck.  I did a comprehensive rebuild article for the magazine with the same level of detail you find in my books.  That step-by-step set of instructions for rebuilding your BBD is at: http://www.4wdmechanix.com/Rebuilding-the-Two-Barrel-BBD-Feedback-Carburetor.html

 

Read my instructions and steps thoroughly.  I believe that if you have a diagram, a carburetor rebuild kit and my illustrated instructions, you can rebuild and get your BBD carburetor functioning as new...Really!

 

As for the O-ring that flew out from the air horn, look over the article's illustrations.  Let's pick it up from there, SramblingMan.  You should discover the location from the photos...or I can furnish better illustrations in a factory-level parts schematic, just let me know!

 

To take the guesswork out of your carburetor adjustments, here is the adjustment procedure for a YJ Wrangler version of your Scrambler's BBD carburetor:

 

Idle Adjustment of YJ BBD.pdf

 

Moses

Link to comment
Share on other sites

  • Administrators

ScramblingMan, welcome to the forums!  Very pleased with your participation, and the whole aim with these forums is to bring members up the learning curve by sharing information.

 

First, with your Carter BBD two-barrel, you're in luck.  I did a comprehensive rebuild article for the magazine with the same level of detail you find in my books.  That step-by-step set of instructions for rebuilding your BBD is at: http://www.4wdmechanix.com/Rebuilding-the-Two-Barrel-BBD-Feedback-Carburetor.html

 

Read my instructions and steps thoroughly.  I believe that if you have a diagram, a carburetor rebuild kit and my illustrated instructions, you can rebuild and get your BBD carburetor functioning as new...Really!

 

As for the O-ring that flew out from the air horn, look over the article's illustrations.  Let's pick it up from there, SramblingMan.  You should discover the location from the photos...or I can furnish better illustrations in a factory-level parts schematic, just let me know!

 

To take the guesswork out of your carburetor adjustments, here is the adjustment procedure for a YJ Wrangler version of your Scrambler's BBD carburetor:

 

Idle Adjustment of YJ BBD.pdf

 

We can also discuss why your fuel supply was dry if that's still in question.  Your CJ 4.2L has a mechanical fuel pump and a filter alongside the valve cover...

 

Moses

Link to comment
Share on other sites

The 83 Scrambler is gettng fuel to the carb. — I replaced the fuel pump & filter and still nothing. I have poured a little fuel in the carb and it starts right up but as soon as fuel is gone it dies. Since it was sitting for a while I put HEAT in the gas tank and added 5 gallons of fresh 93 oct. non-ethanol gas. 

Hopefully I can get back to it this weekend, if the weather will cooperate.

 

Thanks for any & all help

Link to comment
Share on other sites

  • Administrators

Clogged venturi tubes or other fuel circuits could be an issue here.  When you have the time, look through my article on rebuilding the BBD.  Also, regarding the O-ring, did you remove the bowl vent, too?  Look at that illustration near the top of the article.

 

Before you get involved with the carburetor again, disconnect the fuel hose at the carburetor side of the fuel filter near the carburetor.  Safely route a piece of fuel hose to a can away from spark and heat.  (You may need to cap the fuel filter return hose nipple to prevent a leak.)  Remove the high tension (spark plug gauge size) wire from the distributor cap to the coil as a safeguard.

 

Have someone crank over the engine.  The fuel pump should be moving fuel.  The normal volume for your pump is 16 oz. in thirty seconds with the engine idling.  Since you cannot get the engine to run, the cranking volume will be less but should be a steady flow, spewing in pump strokes.  If you have a gasoline pressure gauge, the fuel pump pressure is 4-5 PSI on your pump's application.  You should have the 3-pipe fuel filter and all EVAP components hooked up.

 

If there is no fuel moving through the pump, the fuel tank pickup could be plugged, or there might be a restriction in the system (doubtful, the engine ran when you shut it off last year).  Then there's the often overlooked issue with the emission system and possible trouble with the EVAP hoses and components that can cause a fuel lockup in the system.  We'll talk about that if you're not getting fuel to the filter. 

 

I'm not quick to condemn parts and start the "parts replacing" strategy.  One item that can cause havoc on the 4.2L engines with EVAP, however, is the fuel tank cap.  If the cap is not pressurized and sealing properly, there can be a fuel supply problem.  I'm bringing this up, because in the worse case scenario, there can be little or no fuel to the carburetor bowl.

 

For the moment, let's not "borrow trouble", there's plenty available if you cannot find a problem at the carburetor's fuel circuits.  Since you do have a carburetor kit, I would definitely follow through with the rebuild, using my article and this forum if necessary to assist.  There is a lot of creative misinformation on the web about the BBD and how you should strip off the Sole-Vac and other components.  This is a senseless approach unless done systematically, and that's not easy with so many components and functions overlapping.  Rebuilt to factory, "blueprint" standards like I describe, including the Sole-Vac system restoration with alcohol as a cleaning agent, you can get great results.  You do need to make sure all of these components function properly, though, and that the fuel, vacuum and spark systems interact as designed. Not always easy with a 1980-90 4.2L Jeep inline six!

 

If your Jeep CJ-8 Scrambler is stock and intact under the hood, consider yourself fortunate.  Any missing or defective pieces within the fuel/carburetor, vacuum, spark control, fuel metering, EVAP or exhaust systems, plus the electronic modules and wiring, will present a troubleshooting challenge.  While many CJs and early YJ Wranglers have been converted to Mopar, Howell and MSD Atomic EFI systems (click here for details on all three systems in my 5-page article on the MSD Atomic installation), you may not want to go that expense.  I'm not a big fan of the Weber carburetor "cure", however, that's a less costly alternative.

 

To instill owner confidence around later CJ and YJ Wrangler 4.2L engines with the BBD carburetor and OEM spark system, I like to use this metaphor:  We tested these vehicles over the Rubicon Trail in fully stock, showroom fresh form.  They behaved like any other carbureted engine in terms of side slope flooding and altitude sensitivity; however, they ran very well.  I'm a restorer and believe that the OEM system, when working properly with its integrated components intact, can be a success story.

 

Moses

Link to comment
Share on other sites

Hey Moses, 

 

Thanks for all the info. I have been reading a lot of your articles, but being an idiot when it comes to mechanics, a lot of it went way over my head and looked German to me. I continue reading, hoping some of the gaps will be filled in later. The only way I am going to learn is reading & getting in there and take some things apart and put them back together. Been too busy during the day to take the rest of the carb off, but reading at night. Hoping to take the rest of carb off tomorrow. I want to take it apart so I can dissect it & understand better. 

 

I can tell ya gas was getting to the carb. The venturi tubes were completely clogged. Sprayed them with Sea Foam and blew them out with air. I went to get carb. cleaner & reading the can, I realize rubber, plastic parts & electrical parts will not be dipped, but it states certain parts should only be dipped for 45 mins. max and should also be coated with ?something?? after dipping to prevent future corrosion or something like that. All dependent on what type of metal, aluminum, etc...I have no idea what each part is made of. Any help here?

 

Obviously I am going to finish rebuilding this carb, but how much does that MSD Atomic EFI system cost? I had a holley pro-jection put on my 84 J-10 360 V-8. The best money I spent on that truck. Ran perfect for a loooong time. And would I be able to install that system?

 

Thanks Again!

Link to comment
Share on other sites

  • Administrators

Hi, SramblingMan!  Glad you're braving this job.  As for the materials that cannot be dipped, I outline and illustrate them in the article.  This includes electrical parts, any rubber diaphragms or seals, plastics and other parts described.  Your parts dip mentions adding a coating after stripping the parts, and that applies to parts that will then be exposed to the air and prone to oxidizing.  This is not a carburetor concern and refers to general parts.  The carburetor runs in a hot, under hood environment.  I do, however, recommend drying all parts thoroughly—as soon as they come out of the post-cleaning water rinse.  Otherwise, they will rust.

 

Note: The BBD carburetor body and air horn, the throttle plate and valves, all fasteners, the venturi, brass and pot metal parts, all steel linkages and such can be dipped.  Parts that can be ruined would be items like a phenolic plastic float and other plastics, some of which have protective coatings. 

 

Even if my article and how-to sounds "German", Greek or any language you've not mastered, you will benefit from matching the images with what's on your work bench.  This and the instruction sheet that came with the carburetor kit will help get you through this—and if not, simply post a question or concern here, and I'll respond!  We'll get your BBD carburetor to OEM specs...

 

As for 4.2L EFI conversions, of course there are major gains:  better fuel metering, compensation for altitude, the vehicle can run smoothly on any slope, plus more horsepower.  The Mopar EFI, due to its Multi-Port Injection design with an injector at each cylinder, will conservatively provide 50 extra horsepower with no other modifications.  And better fuel efficiency in the process!

 

As for these EFI kits, if smog legality is a concern, both the Mopar EFI and Howell TBI have 50-State legal status.  MSD is working on this, not yet CARB/California approved but likely soon.  I'm encouraging MSD to seek a 4.2L inline Jeep six E.O. number;  Dan Hiney and I have all findings and installation details from the magazine's project.  Dan's YJ 4.2L with Atomic EFI now achieves California's required tailpipe readings.  The system is a prime candidate for a 1980-90 Jeep 4.2L E.O. number.

 

In cost ranking, at current full-retail, the Mopar system is most expensive, MSD Atomic EFI is second, and Howell's TBI system is the least expensive.  This may influence your thinking.  As for installation, Dan's YJ Wrangler serves as a prototype for both the Atomic EFI and Howell's TBI system.  If you'd like to see some details from a Mopar EFI kit installation, that's also available at the magazine: http://www.4wdmechanix.com/How-to-Tuning-the-Fuel-Injected-Jeep-Inline-Six-Stroker-Motor.html.

 

Let's keep the lines of communication open.  You're right, the only way you can rebuild a carburetor is with your hands.  We'll make that a success story, and you'll be that much further up the learning curve at automotive mechanics!

 

Moses

Link to comment
Share on other sites

ScramblingMan, the best way to know what each system would cost in your area, due to the fact that prices can differ radically in different parts of the country, or even in your own state, would be to go to the manufacturers websites listed in the magazine, then other online suppliers, and then your local parts stores, in that order.

 

I say in that order because i have found that companies that advertise in magazines at times give a discount when customers are referred from that magazine. The company is most knowledgeable about whatever parts you are searching for. Online suppliers, while usually being somewhat knowledgeable about the products they carry, usually only get their knowledge from whatever the manufacturer told them in whatever info papers they send with the product. 

 

Owning a computer repair shop and parts distributorship, i see this one quite a bit. A product will come in, accompanied by a sheet of paper with the minimum specs and info for that product. Local shops, while usually knowing what they are selling, also tend to cost more than online suppliers.

Link to comment
Share on other sites

I took the rest of the carb apart. Went pretty smooth except the main metering jets. First one came out OK, second one stripped all to heck. Any idea how to get it out now?

 

The float has a small ding on the top of it, otherwise looks pretty good. Is that going to need to be replaced?

The float and the bowl were actually pretty clean.

 

I saw where you recommend Mopar rebuild kit. If not Echlin from Napa. I had already purchased a Walker kit from O’Reilly. Should I go ahead and use the Walker or is it gonna be worth returning & getting the Mopar?

 

Thanks again for ll your help!!

 

BA

Link to comment
Share on other sites

  • Administrators

BA, sorry to hear about the metering jet, which is not available in a kit and would be difficult to locate as an individual part.  If that jet is still securely in its threads, and if the bore and flute of the jet is not distorted (just the screw slot is twisted up), leave the jet in position.  Smooth out the distorted brass screw slot material so it will not slough into the bore or elsewhere in the passageways.  You'll need to make sure there is no debris in the fuel circuit for the jet:  Use compressed air or a vacuum, or both.

 

Ironically, one of the least risky ways to loosen a brass jet is with an impact screwdriver.  Without sounding like a shill for Harbor Freight once more, they happen to have an inexpensive driver, commonly used on motorcycle case screws that are notorious for stripping out their heads, especially the Phillips variety.  Here is the example: http://www.harborfreight.com/impact-screwdriver-set-with-case-37530.html

 

The impact screwdriver bit's shank must be long enough to clear the float bowl body.  This tool drives downward while rotating at the same time.  Downward pressure results in a slight relief of the screw (jet in your case) tension in its threads while rotational force applies simultaneously—ingenious, really.  There's no guarantee that this would prevent twisting the soft brass slot out, but you might have a better chance at success.  If you try this, experiment with various levels of hammer force, beginning with the lightest and finding the one that just works.  The tool is reversible for removing or tightening fasteners, and it accepts sockets, too.  In this jet's case, sounds best to leave well enough alone if you can, you may not be able to find a replacement jet readily.

 

The ding atop the float should not affect anything, as long as the float can be set accurately for height and drop.  The concern with the float adjustment is strictly the position of the needle in its seat with the float at various positions.  From what you describe, as long as the float can float in gasoline and will not leak, it can move the needle in and out of the seat and set the fuel height properly in the fuel bowl.  Talking about the replaceable seat, if you want to avoid brass screw slot issues here, make sure you to use a screwdriver big enough to fill the slot's width and shoulders.  This will be least likely to damage the new seat during installation.

 

I like the Mopar and Echlin kits for both their quality and the details in the instructions.  If the Walker parts look decent, and the instructions are sufficient (we can supplement from my library if necessary), you should be okay.

 

If you can, share/attach a photo of the damaged jet, I'd like to assess its condition.

 

Moses

Link to comment
Share on other sites

Oh, that jet is trashed now. I tried using an easy out and all it did was eat up the brass. Now the diameter is much bigger.

I found a couple places to get new jets, Quadrajet & Mikes Carburators both had jets. Then the question was what size jets?

They stated the size of the jet should be stamped on the jet, but I could not find it on the one I was able to take out.

I did not order any until I get the old one out, which is looking doubtful.

 

Not sure what to do now. Order the main body & jets or am I going to have to buy a new carb.

One on e-bay for $165, plus 16 for shipping — $181 total. That would suck because I wanted to learn how to repair/rebuild.

Didn’t seem too difficult until I got to that one jet. Everything else went pretty smooth

 

Before I even tried to pull the first jet out. I wondered why they even needed to be taken out since all that matters is the cleaniness of the interior of the jet.

 

I looked on the web for the EFI systems. I’d love to go that route, but cannot afford it at this time. Is the Mopar system worth the higher price over the MSD system?

 

Thanks again 

Link to comment
Share on other sites

  • Administrators

BA...Your Scrambler's 4.2L is an '83, and the main metering jet size is 2.35mm or 0.092".  On the head of your good jet, you might see the number stamped into the jet.  Regardless, this is the main metering jet size by measurement.  There are two model carburetors:  8383 and 8384.  Both use this size main jet size.

 

As for getting out the old jet, you can try a square easy-out.  These are tapered, square shaped and often will work where the common "screw" type does not.  Brass is tricky, as you've discovered, but you haven't ruined the body, so you're still in the game for rebuilding this carburetor.  The replacement jet should not be expensive and can be shipped inexpensively by Priority Mail.

 

Personally, I would hang onto this project unless the body is shot, which it is not.  Look for a square extractor like I describe that will fit into an orifice of 0.092".  With care, you can even drill the jet out slightly.  Use the good jet for judging what size drill bit diameter will not damage the threads in any way, and just drill through the jet, not into the body

 

Note: A machine shop would likely drill the jet to just inside the threads.  The jet's head would be remove carefully with a larger bit, without contacting the carburetor body.  Using an extractor at that point would remove the remaining thread material while carefully avoiding damage to the casting's threads.  With tension relieved, the threads would come out easily.  If you don't feel comfortable trying this, don't try it:  Concentrate on the square extractor approach, maybe drilling off just the head of the jet first.  Use care, this is still a viable carburetor for rebuilding!

 

Do you need to remove these jets for rebuilding?  Your instincts were right:  Not always.  Yes, you can get the carburetor dip more readily into the circuits with the jet bores open, but that's not essential.  With care, a couple of dips and thorough rinsing, plus use of compressed air after the final rinse, and you should have a clean carburetor.  The 0.092" orifices are plenty for carburetor cleaner to move through the passageways during the dip.

 

The MSD Atomic EFI is a nice setup, however, it's not 50-State legal yet.  If emission inspection is an issue, you'll need to wait on this one.  In real world terms, Dan Hiney got passing tailpipe readings by dialing in the Atomic EFI, it simply does not have the California E.O. number at this point. 

 

Mopar's system is outstanding.  It's off-the-shelf Chrysler/Jeep parts for a stock 4.0L, simply made to fit the 4.2L block.  This "kit" has been out since the mid-'90s in two forms:  Two-rail EFI (early, based on '94-'95 YJ Wrangler) and single-rail ('97-up version TJ).  Either type works very well, and at the magazine articles and 4.6L stroker build videos, the Mopar EFI/MPI topic is frequent.

 

A key advantage of the Mopar MPI (multi-port FI) is that the injectors are at each cylinder port.  This means even fuel-and-air ratios per cylinder, a tremendous improvement over a centrally mounted carburetor or even TBI.  The outer cylinders on an inline six have difficulty drawing the same volume of air/fuel from a central point.  MPI eliminates this stigma by delivering the same fuel mixture and volume at every cylinder.  Though costlier, the Mopar system offers a large performance and fuel efficiency gain, OEM parts for service, and even some OEM diagnostics with minor tuning capability.

 

Moses

Link to comment
Share on other sites

  • 1 month later...

Howdy Moses,

 

Got distracted with many other things, but I’m now back to the BBD Carb.  The last time I posted, I was dealing with a jet that would not come lose. I ended up cracking the main body trying to get that jet. Spent some time checking e-bay for used carbs. Finally got one for $5.50 ($15 for shipping) $20.50 total for a filthy used carb to use the main body only. I have cleaned all pieces pretty good and reassemled. I just put the carb back on and still can’t get the jeep started.

 

A few questions. I still have not figured out where that little o-ring seal popped off. It popped off while taking it apart & the rebuild kit also has one in the kit, but does not show where it goes. You had mentioned the vent, but I don’t see where it would go there. I understand the round rubber flap seal and have it in place, but still clueless where the o-ring seal goes. Did not see one on the used carb I bought either.

 

The other thing that has me confused is I have 2 exploded view diagrams. One from the Walker rebuild kit and one in a Chilton manual.  The Walker diagram only has one ball (small)—pump disc check—venturi cluster. The kit comes with two- Small & Large. The Chilton diagram has two balls, the venturi one and one with the accelerator pump plunger. Who is right?

 

I put the carb back together following the Walker diagram and only put one ball check in. Could this be my problem with it not starting?  It is getting fuel now, so I am one step closer. While trying to start I didn’t see the choke activating and not sure why. The choke assy. cover was warm, but I did not see any movement.

 

Another question—what is the dashpot? Is that something to do with emissions, because I don’t have that. My buddy that used to work on this  jeep  eliminated as much as he could.

 

One last thought that keeps coming to me while going through these manuals — they tell where things go but don’t really explain the why’s or purpose of these parts.

 

Any suggestions, help?

 

Thanks

 

BA

Link to comment
Share on other sites

  • Administrators

Hi, BA...Glad you found an inexpensive Carter BBD body.  Answers to your questions:

 

1) If the choke cover was warm (electric), you likely had the key on long enough to open the choke.  Whether the choke is set right or not, you do need to adjust it when completely cold.  Don't turn the key on, you'll heat up the choke coil and open it.

 

2) The dashpot is a device to slow the throttle return on deceleration.  It can be vacuum actuated or simply a bracket with a diaphragm and spring that "cushions" the throttle return when you release the pedal.  This prevents the throttle from slapping shut, which can cause venturi effect fuel enrichment or backfiring.  My policy:  If devices were in place, there was a reason.

 

3) The Jeep factory workshop manual covering your year model actually does describe the functions and pieces of the carburetor. For each of my books, I depended on factory workshop manuals for first generation data.  This is the most reliable approach, as second generation information can lose something in the translation.

 

4) The accelerator pump circuit also uses a check ball, accounting for the two in the Chilton manual.  Your carburetor needs both check balls, the small one at the venturi cluster.

 

There should be a "tag" on your carburetor that has a list number on it.  (Number should be an 8383 or 8384.  Check it.)  Please share the numbers, and I will put together a factory parts schematic for your carburetor, showing individual pieces.  It will help you identify the parts and even details like the number of check balls that need to go into place.  You won't have to second guess with these details!

 

If you get you vehicle production date and the tag details to me promptly, I'll gather up the info before I leave for the Off-Road Expo early Friday morning.  Otherwise, I will not be able to reply until Sunday night...

 

Moses

Link to comment
Share on other sites

My carb is missing the tag, but has a number on the body 2731. The carb I bought has a tag of 8384.

 

I will put the large check ball in with acc. pump.

 

The used carb didn’t have the dashpot either. I guess I need to find one. Don’t want any backfiring.

 

Think I would be able to find your manual @ local books a million or do I have to purchase online thru Bently Pub.?

Link to comment
Share on other sites

  • Administrators

ScramblingMan, the 8384 will do, that's very common.  The dashpot may be available from NAPA/Echlin.  My Jeep CJ Rebuilder's Manual: 1972-86 Edition would be a valuable read and has been available (usually discounted) from 4WD Hardware and Quadratec.  Advance Adapters also carries my books and, of course, my publisher Bentley Publishers...I'm additionally recommending that you secure a copy of the official Jeep/AMC factory workshop manual, which can often be found in good used condition on eBay or through used automotive book stores.

 

I have attached a PDF of the actual Mopar Parts catalog pages listing the 8383 and 8384 series carburetors.  PDF is very cool:  You can zoom into these pages for extraordinary detail!  This will provide not only the schematic of parts (orientation, fit, etc.), it also provides the official Mopar part numbers for many of the parts if still available.  If not available from Mopar, you can cross over to Echlin, maybe even Federal-Mogul/Carter and other brand parts:

 

1981-86 CJ BBD Carburetor Mopar Parts.pdf

This is the official Mopar Parts listing and diagrams for the 8383 and 8384 Carter BBD two-barrel carburetor used on Jeep CJ models in the 1981-86 era (also similar to the '87-'90 Jeep YJ Wrangler 4.2L BBD carburetor). Members have ready access to this PDF download—if you're not a member, please join us and get involved in the discussion!

 

Let me know if you need any other information.  I have adjustment data and everything else related to the BBD carburetor and its interface with emission controls and whatever.  We'll keep you going here!  This is a learning curve on a fairly involved carburetor.  Your success will be a confidence builder and help you better understand your Jeep.  We'll get through it!

 

Moses

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...