Well...... I just got done doing this for the WEBER 34 DGEC. I had a hard time getting help. The carbs do run very rich and yours may use the same jet or close. Please post what Run Jet and Idle Jet you have for primary and secondary onthe Weber 34 DGEC. Write down what you start with for Jets and settings, write down your changes and what you like, what has hesitation in primary or secondary, what is too rich or too lean. This should get you close or very close if things go the same for you as for my 1978 CJ7.
Caution when these things run tooooo.... rich the gas can wash the piston walls of oil and cause an issue. Too.... lean and get too hot and not good. I bet your plugs are black and sooty running very rich.
Here is a write up I did for the Cj Forum. This worked well for me and ALL HWY got 24/25 mpg with MSD ignition. REad on this will help you.....
This is what I have found to work on the WEBER 34 DGEC as far as IDLE & RUN JETS. The Weber 34 seems to run very rich and smoke. I think this will fix the operation for most of us. I have a 1978 CJ7 with Rebuilt 258 Long Block, Borla Header, more modern Jeep water jacket 2 barrel intake---so a very good base line. All pollution stuff removed and only vacuum stuff is Distributor, PCV Valve, Power Brakes. I updated my ignition with the TEAMRUSH & Grounds to Head & DuraSpark Ignition Modual. Still rich but helped. I then upgraded to Summits MSD, multispark ignition and helped a little more. So looks to be the Weber carb is too rich for stock or modified 258 as shipped. I also STRONGLY recommend the Holley Fuel Pressure Regulator set at 3 to 3.5 psi. Without the low pressure fuel the Weber will run rich from my reading & factory. Stock Weber set up not only makes the plugs black but also contaminates the oil with gas and makes it BLACK and lowers the oils protection level. If you have black oil change it.
Order these small group of jets and install them. Run your 258 around town and see if this helps with the smoking. Then pull a plug after 10 miles or so. Then run 10 miles of HWY and pull over and pull a few plugs and take a look. Good running plugs will be tan with small amount of black on the base ring of threads. This jet combo should get you very close.
PLEASE FAX Order to
631-863-2760 WEBER CARBS DIRECT AND INSTALL THEM. THESE SMALLER JETS JUST CAME INTO STOCK. THEN EMAIL ME BACK TO SEE IF THIS WORKS WELL. IF THIS FIXES YOUR CARB OPERATION THEN POST TO WEB HERE, JEEPFORUM , AND OTHERS CAN THEN ORDER THE SMALLER JETS.
The jets for the 34 are not on the web site as of today, they are replacing their phone system so hard to reach them on phone, so the fax is the easiest way to place this small parts order.
Tech 800-871-3405 and gen # 631-863-2036
NOTE: Choke side is Primary side of carb
FACTORY SHIPS WITH STD Jets Run 150/147 Primary/Secondary
FACTORY SHIPS WITH STD Jets Idle 65/47.5 Primary/Secondary
This is what was shipped with my carb. This JET SET UP smoked and plugs were black at idle and run.
New Jets Run 135/140/147 #73840.135 and .140 $5.95 ea
New Jets Idle 40/35/35 # 74404.035 jets Qty 2, one of .040 #74404.040 $6.60 ea
I suggest starting with this set up
Run 140/147 Primary/Secondary
And the Holley Fuel Regulator, can order from them also, orders over $49 ship for free.
Runs well 600 to 4000 rpms and pulls the whole way. Normal around town driving plugs look very nice, tan.. The hwy plugs are still tan but little lean. I drilled out the 130 Run jet to equal about a 145 using the 147 using the drill bit shaft as a feeler gauge. Looser than the .140 and almost as large as the 147. BOTH SET UPS WORK VERY VERY WELL. The smaller Idle jets, .035 / 035 will affect the RUN circuit and make it a little leaner. Factory informs the Idle Jets supply about 15% of the fuel when the carb is in the run mode.
I sell nothing car/jeep related, nor do I have any relationship with Weber. THIS CARB DOES WORK PRETTY WELL AND WOULD LIKE OTHERS TO TRY THIS AND POST UP. ONLY THEN WILL WE KNOW IF WE HAVE A GOOD GENERAL SOLUTION FOR THE 258 JEEP.
Here is a pic of the Weber 34 with the top plate removed. There are five screws to remove to lift off the top plate. There is also a bolt under the electric choke & support bracket that needs to be removed also. When reinstalling, the choke cam needs to activated to allow the top plate to sit flat. I would hand center the gasket for top plate and hand insert all fasteners before tightening up any of them. Recommend the fastners be bottomed out slowly on reinstall. Snug them up slowly crossing over the carb many times.
The Idel Jets are external on the carb and the brass head bolts can be seen between the bowl for float and venture tubes. There is one on the primary side and one on the secondary side. All Jets are stamped with the size.
Here is another angle of Idle Jet. Just below the top plate mating surface.
The Run Jets are in the bottom of the bowl where the float would be. Here is a closer picture they are at the very bottom. The one on the right /choke side is the primary side for Idle & Run.
I also had a quality control problem that affected my carb operation and the top plate removal and installs. In this pic you can see how the top plate GASKET IS CUT by a 1" x .020" casting flashing ridge along the bowl. In the pics of the bowl above you can see the ridge. This caused a complete carb failure on the Second REinstall and would not run period. I had to replace the gasket and grind down the flashing imperfection. I suggest you remove an flashing imperfection you find also. I am curious if others have different stock jets than mine due to this possible air leak. Looks like all Webers 34 sent with same jets from what I have seen so far, even though Weber tells me these are bench tested and set up for the Jeep 4.2 liter.
To solve the flashing problem I stuffed the bowl with rags, covered with packing tape, and covered the venturies with packing tape and used my dremel tool with fine stone or drum sander and flattened out the ridge till smooth. Blew away any metal filings from work with compressed air. Cleaned out bowl again and wiped and sprayed air. Tried to keep as clean as possible not to plug up the carb fuel passages with debree
The Weber Jets are metric and the Jet Numbers are the metric hole size. I converted them to thousands of inch to compare and use % changes to see how much of a change I made. The jets I selected are much smaller.
When I put in the smaller Idle jets P/S 40/47 vs 35/35 my idle when up from 650 to 1100 rpms with no other changes. THE SMALLER IDLE JETS ALLOWED ME TO BACK OUT THE IDLE SCREW EVEN MORE.... BACKING OUT THE IDLE SCREW CLOSED THE PROGRESSION PORTS AND MADE THE RICH IDLE CONDITION EVEN BETTER. This was the second change of the Factory Stock STD Jets Idle 65/47.5 Primary/Secondary (P/S) that came with the carb in addition to swaping the P/S sides. I like the smaller RUN jets on Primary to get better fuel economy and the secondary to be bigger when you get on it, the gas pedal. Weber seems to ship the larger jets on the primary. I was able to back out the idle screw by 1 to 1.5 turns. My idle screw is now in about 1.25 turns from when it first touches or bottoms out. My manifold vacuum level also went up from 14/15" HG to 18/20" at 650/700 rpm idle with the smaller 35/35 Idle Jets and the idle screw at proper 1.25 turns range.
THE REASON..... WHEN THE WEBER 34 IDLE JETS ARE TOO... BIG.... USERS NEED TO SCREW DOWN THE IDLE SCREW TOO FAR AND EVEN CLIP THE LOCK SPRING TO TIGHTEN DOWN FURTHER TO GET THE ENGINE TO IDLE. WITH THE CORRECT/SMALLER IDLE JETS THE IDLE SCREW WILL ONLY BE TURNED DOWN APPROX 1.25 TURNS AFTER TOUCHING BOTTOM. WITH CORRECT IDLE JET SIZE THE IDLE SCREW SET APPROX 1.25 TURNS, THE THROTTLE PLATES ARE CLOSED, AND MANIFOLD VACUUM LEVEL SHOULD READ 18 TO 20 AT IDLE ON A SOUND ENGINE. OLD engines might be a little less. THE CLOSING OF THE THROTTLE PLATES CLOSES OFF THE PROGRESSION PORTS HELPING THE RICH IDLE PROBLEM EVEN MORE.
Once I got the smaller 35/35 idle jets my run jets were too lean now. The Idle Jets supply 15% approx of the run jet circuit. So kept increasing the Run Jets size till the plugs looked nice tan color. Run Jets 140/147 was just a little lean on the hwy. I drilled out the 130 to EQUAL A 145 and that combo of P/S Run 145/147 and Idle 35/35 that seems to run well for me.
You can also take one of the smaller jets and drill it out with english or metric drill bits to get jet size not offered. I drilled my 130 run jet to 145. This was my final setting used in Run primary jet. You may want to use two 147 / 147 Run Jets.
Please write down and post your stock jets that came installed on your new Weber 34 so we verify the same as mine or different. Also let us know how this set up ran on your 258 or even 232.
Print the reference links in case they get moved or deleted. This is the most info you will find on the Weber 34 DGEC and Jeep I6 in one spot. This should also help you with the other Weber carbs also. AS ONE OF THE TUNE LINKS SAID.... ALL THE WEBERS RUN THE SAME!!
Last note. The yellow staining on the outside of the carb is gas. I think it is from the top plate gasket being cut by the casting flash on bow lip. It could also be the carb was so rich the gas come out the piviot points.
My electric choke, electric manifold heater and water/collant jacketed intake are working perfectly and yours should be also. If you have the older cast iron manifolds make sure your heat riser flap moves freely, is lubricated, and working. This is a flap between the warm exhaust and the cold intake air.
I don't have time to post much now, build crunch time, but only have one real comment on the so called 'weber' 34 clone carb.
In my firm opinion if you bought this clone carb made by a French Moped company, Solex, you just plain got ripped off and you should send it back to get a Real Weber if that is the brand you prefer or any other "Real" carburetor like a Holly remanned Carter BBD or an MC 2100 or.....
Power to you Fred for helping out others who also got that clone, good post.
And don't forget that "any" carb you buy needs a kit put in it every time your engine needs plugs, it is also part of a major tune up according to the Jeep CJ maintenance schedule and always got done at any garage at tune up time I ever worked at.
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Thanks for your comments, I/we value your opinion, and nice your actually read (possible) some of the Weber Posting Information and Web Links prior to all your negative posts in the past day. Some of your recent comments showed me you never read thru the WEBER POSTING & LINKS. Knowledge and the web is a great thing. This information is true for All THE WEBER CARBS, THEY ALL WORK THE SAME.
Many if not all multinationals companies use subcontractors to manufacture for them. Then we need to throw out many other companies with this bath water. At least they are not made in china, they are all made in Europe, in this case England and France and have been for what 50yrs, used on Porsh, BMW, Audi as oem and aftermarket.
THIS THREAD, has been looked at by nearly 900 JF members at this time. You are the first one to pee on it. You also pee..ed on 4 other threads about Weber Carbs. I ask you to consider removing the above post or at least reword it so you do not scare anyone to the point they believe not and give up on their Weber Carb.
I believe more and more of us will find the Weber 32/36 and 34 will work just fine. As posted in other threads looks like Weber is already shipping the 34 with smaller jets than I am recommending. ONCE I get more proof what is close to correct with VALIDATION of other success can I ask the factory to change to the above set up.
There are several posts saying the weber is working fine, EXCELLENT ACTUALLY. There are LOTS of post where JF folks are saying they need help. I was one of the folks that needed help and gathered as much information as I could and put it in one spot.
I posted this link to the YJ Thread last night, they need help too!!
Our converstions were on other threads and I feel you should have stayed there... those 2-3 threads that are current in the past day. Maybe next year at this time you will have a different opinion.
Keep the faith, it does work, regards,
Last edited by Fjguercio; 02-12-2009 at 11:46 PM..
Just for a little confidence in WEBER CARBS here are a few recent postings. I hope the guys do not mind I copied over some of their statements in whole. I even added the rotary pump to the write up above several days ago.
Thank you JeepForum,
PS I add will a short video spring time when all the salt is away and the CJ comes back out. She runs like brand new.
Originally Posted by CJhollic
Adjusting a Weber is just as easy if not easier than a BBD and no need to rebuild it once a year. To each his own, but if you can tune a BBD you can make a Weber purr. Putting the proper jet in at the initial set up is key as well as a FPR. Both are clearly stated in the instructions. I wouldnt run any other carbuerator.
Originally Posted by rj_ton
Dude my 34 runs great out of the box, and its supposedly a solex with the weber name on it. look on page 1 about the proper fuel pump to use. This is where a lot of peoples problems stem from they just don't know it.
It shows how the Carter 4070 rotary electric pump is the one simple answer to this reoccuring question. It is a high volume low pressure rotory pump (constant flow, not a pulse like other crappy elec. pumps or like the stock mechanical pump.) Regulators only decrease the life of a pump. So why not find a pump that operates at your needs? The 4070 pumps at around 4psi but flow around 60-70 gph. Perfect for what any weber needs! It costs around $80- $100 and comes with everything you'll need except a little extra hose and wires. When I found this I was sold, I bought my Weber, did the Nutter bypass and only a little adjustment. Make sure the remainder of your vacuum lines that you use are routed properly and reset your timing on your distributer 14 degrees BTDC @1600 rpm.
Originally Posted by j33pman
I have the Weber 32/36 on my Jeep, Came with it.
Bought a jet kit and a FPR for it. Runs sweet.
Currently getting 16 MPG with 2.73's and 33" tires
Originally Posted by smitkev2
I have the same setup as you do. Yes, Nutter. The Nutter has nothing to do with the carb directly. I have been in your situation more times than I can count. My bet is your spark plugs are black if you pull them. Clean them, get new ones, whatever, I have done both. Then print off the Weber directions for getting the fuel/air mix right, I can dig them up but just look on redline website for the steps. Follow them exactly. Should be up and running in no time.
If you need help nutter or need advice, check my signature. good references on there.
Not related to your question, but i recently put on an HEI dist. and have not had a problem since. I'm only telling you this because I was you 11months ago with all the same problems.
Nice post you got going. And like you said, all Webers work the same.
I had a Suzuki I but a Weber on and even with a Header, Crane Cam and other goodies, I was able to get such low emmision out of it on the dyno used in our state the inspector re-calibrated his machine to make sure it works. I went from having to take it to a emmision specialist to make it pass sometimes with a waiver to no problems at all. I even found that the Weber used on the conversion was almost the same as used on my old Dodge Omni
Originally Posted by SuB8HaVeN
I have a Weber 34/34 right out of the box with no fuel pressure regulator and mine runs amazing. It doesn't hesitate or studder at all on inclines...
Originally Posted by wwhitby
I run a Weber 32/36 on my CJ. I didn't need an electric fuel pump (just my stock Jeep one), but I do use a fuel pressure regulator. The Weber is set up for about 3.5psi and the fuel pump puts out @7psi.
The Weber was easy to install and tune. I haven't had any problems with it at all!
Originally Posted by SuB8HaVeN
My all-around favorite would have to be a Holley 2300 for simplicity, downright reliability, and easy tunability. I run the progressive Weber 34/34 on my CJ and it gets much better fuel economy than any other 2bbl, and still has some umph. IMO, the Holley is simpler and easier to tune than the Weber. The Weber 32/36, and Holley 5200 (basically a Weber 32/36 clone manufactured by Holley) are also both great carburetors and are very fuel efficient, being progressive 2bbls.
My CJ sees a lot of on-road driving, so fuel economy is pretty important to me. That's why I run a progressive Weber on there.
Originally Posted by onlyinayj89
The same thing was going on with mine, put the weber 34/34 in and runs perfect. Gas milage isnt to good, but its a jeep, what do you expect, ha.
Last edited by Fjguercio; 03-17-2009 at 02:03 PM..
THE LAST PART OF THE JEEP 4.2/258/I6 ENGINE PUZZLE???
Originally Posted by Fjguercio
The Information above on the WEBER 34 & 32/36 and links can help with your Jeep. Below are links for TeamRush, a much, much, much, better set of tune up parts bigger cap/rotar with brass terminals and a process for making sure your computer is not messing up the operation of your Jeep. I also have a link to a nice review of how you can use your weber and clean stuff up. Sorry that post got a little out of hand, but still go info. I could take it all over to a new post if you JF folks think it should be.
These are some of the best examples I have seen on the web.. with pics, they are excellent!!!!
I'm still working on my 36/36 i just got. I called Jose and he sent me new idle jets FREE. I put in the .045 and it seems to idle better and less smoke. I just ordered the CRT Performance HEI dist in hopes of helping the jeep run better. i'll let ya know how it works.