Jeepjeff859 Posted December 27, 2015 Share Posted December 27, 2015 Has anyone on here attempted to put a carb on a 4.0, I'm looking to clean out all the sensor a and electronics in this jeep to make it clean reliable with just a carb and the wires to make it all run Link to comment Share on other sites More sharing options...
gogmorgo Posted December 27, 2015 Share Posted December 27, 2015 You could probably rig something up off an old 4.2, but why? It's a step backwards. Several, depending on who you ask. Link to comment Share on other sites More sharing options...
91Pioneer Posted December 27, 2015 Share Posted December 27, 2015 Why not just go back a little older and get a horse and buggy? Link to comment Share on other sites More sharing options...
64 Cheyenne Posted December 28, 2015 Share Posted December 28, 2015 Why not just go back a little older and get a horse and buggy? :agree: Even the antiquated Renix system is more reliable and performs better than a carb. Carburetors are like incandescent bulbs, worked well in their time, but technology has evolved to make them inefficient and unreliable. I know you could debate light bulbs, but it was used as a metaphor. Link to comment Share on other sites More sharing options...
schardein Posted December 28, 2015 Share Posted December 28, 2015 I have to say I agree. Anyone who replaces a computer controlled fuel injection system with a carb is taking a step back. I say this with years of experience of working on and tuning carbs. For a period correct build, say like my 1967 CJ5 with the factory Buick V6, an aftermarket aluminum four barrel intake and a 390 cfm Holley carb is cool and a big performance improvement. But it took some tuning and mods to the carb to make it perform ok off road. My eyes were opened back in 1998 when I swapped out the 258 I6 in my 1983 CJ7 for a 1991 4.0 with fuel injection. The difference was amazing. And the original 258 had the best running BBD carb I've ever driven (and I've driven quite a few CJs). I'm not a fan of the Renix system, but replacing it with a carb is a step back. The Renix problems, like most all problems with the XJ/MJ platform, are well documented (like here at CC!) and correct fixes are relatively inexpensive. Link to comment Share on other sites More sharing options...
Eagle Posted December 29, 2015 Share Posted December 29, 2015 Even the antiquated Renix system is more reliable and performs better than a carb. Carburetors are like incandescent bulbs, worked well in their time, but technology has evolved to make them inefficient and unreliable. I know you could debate light bulbs, but it was used as a metaphor. I disagree. There are few things as reliable as a properly set up carburetor. Fuel injection may provide better fuel economy across a wider variety of operating conditions, but I have always believed that you have a better chance of limping home with a carburetor than you do with fuel injection. The '95 Chrysler injection system is pretty good, but IMHO there's a certain amount of "cool" factor to running a carburetor. The trick is deciding what carburetor, and then sizing it. If I were doing it, I'd be looking for a progressive 2-barrel, with a small primary venturi and a larger secondary venturi. (Of course, I'm not sure such a thing exists, but I think so.) Or go all-out and get a triple Weber setup ... Link to comment Share on other sites More sharing options...
schardein Posted December 29, 2015 Share Posted December 29, 2015 Even the antiquated Renix system is more reliable and performs better than a carb. Carburetors are like incandescent bulbs, worked well in their time, but technology has evolved to make them inefficient and unreliable. I know you could debate light bulbs, but it was used as a metaphor. I disagree. There are few things as reliable as a properly set up carburetor. Fuel injection may provide better fuel economy across a wider variety of operating conditions, but I have always believed that you have a better chance of limping home with a carburetor than you do with fuel injection. The '95 Chrysler injection system is pretty good, but IMHO there's a certain amount of "cool" factor to running a carburetor. The trick is deciding what carburetor, and then sizing it. If I were doing it, I'd be looking for a progressive 2-barrel, with a small primary venturi and a larger secondary venturi. (Of course, I'm not sure such a thing exists, but I think so.) Or go all-out and get a triple Weber setup ... I see where you are going with this. I will say that I have never had a carb leave me broke down on the side of the road. Fuel injection has, for a CPS. However, both have left me on the side of the road for an electric fuel pump, and a carb has left me stranded for a mechanical fuel pump (none of which is the carb or FI fault, I suppose). I've ran Weber carbs, and in my experience, they required periodic tuning to keep running right (mixture and idle adjustments). I've ran Holleys, same thing to a lesser degree. Took several mods to make it perform off road (bowl vent crossover tube, float bowl baffle, float and idle adjustments) I've ran Quadrajets, which have given me the least problems in factory applications. Time consuming to tune for custom engines though. Since converting to FI in my CJ, it has never left me stranded. I carry a spare fuel pump and spare CPS but have never needed them. Link to comment Share on other sites More sharing options...
Jeepjeff859 Posted January 13, 2016 Author Share Posted January 13, 2016 Found this guy on ebay making adapters for putting a carb on the 4.0 intake, sent him a message and he built a kit with all the things i need to do the swap, i will post pictures when its done http://www.ebay.com/itm/Jeep-4-0-Intake-Manifold-EFI-to-Carburetor-Adapter-Kit/231810062195?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D34494%26meid%3D1abc582bcf7c4d478a3f9186ce131574%26pid%3D100011%26rk%3D1%26rkt%3D1%26sd%3D231806857111 Link to comment Share on other sites More sharing options...
A-man930 Posted January 13, 2016 Share Posted January 13, 2016 It may be a step "backwards" in the drivability and economy departments but it would be simpler; in the end it just plain requires fewer things to operate. It really comes down to preference I suppose. You couldn't pay me to ditch even my Renix EFI for a carburetor because I don't have a clue what I'm doing with one. But if you're more comfortable with carbs then do it! Link to comment Share on other sites More sharing options...
Doc. Posted January 13, 2016 Share Posted January 13, 2016 Is this for the street or an off road rig? I would never want a carb in an off road rig. Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 13, 2016 Share Posted January 13, 2016 Clifford sales complete kit for the 4.0 to convert to carb. http://www.shop.cliffordperformance.net/68-Jeep-40-242-Combination-68J242.htm $1,257.00 Now the kit does not cover the HEI dizzy. you would have to get a HEI dizzy, this one is not bad complete for $149.97 http://www.summitracing.com/parts/SUM-850047 You would also have to either do a dual exhaust or connect the 2 pipes in to one. Now remember unless your exempt this will not pass smog or State inspection. Here in Texas only 1991's and below are exempt or 25 years and older. Off-roading will be find with this kit as long as your not doing steep rock crawling. you can get 21 mpg with that Weber 38 DGAS, as long as your dizzy is tuned right with your carb. People will all say why go back in time with a carb, agree or disagree just giving the info for what you asked. This link is the standard info on how to do it http://www.4wdmechanix.com/How-to-Tuning-the-Carbureted-Jeep-Inline-Six-Stroker-Motor?r=1. This article is more for the 4.2 but much applies for the 4.0 on converting. Link to comment Share on other sites More sharing options...
Jeepjeff859 Posted January 13, 2016 Author Share Posted January 13, 2016 The kit I bought included a carb, hei distributor , all the hardware, and the adapter for the intake so I don't have to swap intakes Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 13, 2016 Share Posted January 13, 2016 where you get it Jeepjeff859? and what about the price wise? From what I can see the design of the EFI intake is not suited for air and gas mixing chamber, but hey if it is cheaper then maybe it is a good option. What used to plug the injector hole? Link to comment Share on other sites More sharing options...
A-man930 Posted January 13, 2016 Share Posted January 13, 2016 From what I can see the design of the EFI intake is not suited for air and gas mixing chamber, but hey if it is cheaper then maybe it is a good option. What used to plug the injector hole? Good point and a good question. Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 14, 2016 Share Posted January 14, 2016 I have read someone put a 4.2 intake on and used a 4.0 header with it. They had to mode the 4.2 intake, by blocking the water jacket tubes going from head to intake, also small mod to block the injector holes. they mounted a 4br carter on it. Link to comment Share on other sites More sharing options...
glundblad Posted January 14, 2016 Share Posted January 14, 2016 Even the antiquated Renix system is more reliable and performs better than a carb. Carburetors are like incandescent bulbs, worked well in their time, but technology has evolved to make them inefficient and unreliable. I know you could debate light bulbs, but it was used as a metaphor. I disagree. There are few things as reliable as a properly set up carburetor. Fuel injection may provide better fuel economy across a wider variety of operating conditions, but I have always believed that you have a better chance of limping home with a carburetor than you do with fuel injection. The '95 Chrysler injection system is pretty good, but IMHO there's a certain amount of "cool" factor to running a carburetor. The trick is deciding what carburetor, and then sizing it. If I were doing it, I'd be looking for a progressive 2-barrel, with a small primary venturi and a larger secondary venturi. (Of course, I'm not sure such a thing exists, but I think so.) Or go all-out and get a triple Weber setup ... Eagle, triple webers are blasphemy. Dual SU carbs all the way. :yes: Link to comment Share on other sites More sharing options...
cruiser54 Posted January 14, 2016 Share Posted January 14, 2016 Even the antiquated Renix system is more reliable and performs better than a carb. Carburetors are like incandescent bulbs, worked well in their time, but technology has evolved to make them inefficient and unreliable. I know you could debate light bulbs, but it was used as a metaphor. I disagree. There are few things as reliable as a properly set up carburetor. Fuel injection may provide better fuel economy across a wider variety of operating conditions, but I have always believed that you have a better chance of limping home with a carburetor than you do with fuel injection. The '95 Chrysler injection system is pretty good, but IMHO there's a certain amount of "cool" factor to running a carburetor. The trick is deciding what carburetor, and then sizing it. If I were doing it, I'd be looking for a progressive 2-barrel, with a small primary venturi and a larger secondary venturi. (Of course, I'm not sure such a thing exists, but I think so.) Or go all-out and get a triple Weber setup ... Eagle, triple webers are blasphemy. Dual SU carbs all the way. :yes: Ever see this Jeep engine? https://www.google.com/search?q=jeep+230+ohc+engine&rlz=1C1KMZB_enUS546US547&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjj_cS8pqjKAhUS4WMKHWcOD-8QsAQINw&biw=1344&bih=734#imgrc=XTqycS4Po5Bj1M%3A Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 14, 2016 Share Posted January 14, 2016 From having a few 258's in the past with carbs. So a Holley 390 CFM four-barrel, or a jetted Weber 38-series would work great . The 258 or 4.2 carb need would be at least 373 CFM is needed to reach max rpm. So a 375 to 400 CFM will do. A 4.0 would run very well with a Weber 38 Two barrel, no need for more then 2 barrels because all needed is 350 CFM, which is the same a EFI pulls at max RPM. I have to add, Dual SU carbs would look cool, but it would work much better on a split intake system. Since they mainly made for old British cars and Volvos. Basically if I remember right you take the cubic inch of your engine and divide by 2. then you take your redline limit, or max RPM and divide by 1728 and you get CFM you need. So a 4.0 is with a redline of 5000 rpms you get 350 CFM. Rochester’s 2G from Chevy 283 V8, Carter BBD from 318 V8, 2300 Holley from the 266 V8 are my picks for old style 2 barrel carbs. I have run all of these and work well on the 258's I have tried the Rochester Quadrajets, and Federal Mogul 4 barrel carbs. They are not my top pick to put on a 258 or smaller. They don't idle very well. Basicly I am saying anything from 350 to 400 CFM would be a good fitting carb. Now I really like Holly , but the Weber 38 DGAS 2 barrel Carb is very well made carb and you can find them very easy for jeeps. Link to comment Share on other sites More sharing options...
Eagle Posted January 14, 2016 Share Posted January 14, 2016 On V8s I always liked the 4-barrel because you had small primary venturis for economy, and larger secondaries for when you needed more airflow and performance. I vaguely remember seeing AFBs as small as 400 CFM, and I always thought that might be a good carb for a 4.0L. Does anyone make a 2-barrel that has a primary and a secondary, rather than two primary holes that are the same size and no secondary? Link to comment Share on other sites More sharing options...
cruiser54 Posted January 14, 2016 Share Posted January 14, 2016 I have had numerous AFBs also known as Edelbrocks now. Always on off road vehicles. Even with modifications, they didn't work well when the going got steep. I got rid of the one on my FJ40 V8 and went to Holley Pro-Jection and never looked back. Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 14, 2016 Share Posted January 14, 2016 Eagle, on 14 Jan 2016 - 06:24 AM, said: Does anyone make a 2-barrel that has a primary and a secondary, rather than two primary holes that are the same size and no secondary? yes the Weber 38mm DGAS has this single Venturis like the old AFB's With high and low 4 barrel. The older Weber 38mm that made pre 1986 did not have. I guess when they updated the design they had in mind what you thinking. I guess the people upgrading from a single barrel to 2 barrel noticed difference in mpg. The Rochester’s 2G had it too, but did not work as well. Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 14, 2016 Share Posted January 14, 2016 Even with modifications, they didn't work well when the going got steep. I got rid of the one on my FJ40 V8 and went to Holley Pro-Jection and never looked back. Yes that would of been such a increase all the way around, and offroading would have improved a lot I bet Link to comment Share on other sites More sharing options...
cruiser54 Posted January 14, 2016 Share Posted January 14, 2016 Even with modifications, they didn't work well when the going got steep. I got rid of the one on my FJ40 V8 and went to Holley Pro-Jection and never looked back. Yes that would of been such a increase all the way around, and offroading would have improved a lot I bet MPGs increased also. Link to comment Share on other sites More sharing options...
outlaw star Posted January 14, 2016 Share Posted January 14, 2016 From having a few 258's in the past with carbs. So a Holley 390 CFM four-barrel, or a jetted Weber 38-series would work great . The 258 or 4.2 carb need would be at least 373 CFM is needed to reach max rpm. So a 375 to 400 CFM will do. A 4.0 would run very well with a Weber 38 Two barrel, no need for more then 2 barrels because all needed is 350 CFM, which is the same a EFI pulls at max RPM. I have to add, Dual SU carbs would look cool, but it would work much better on a split intake system. Since they mainly made for old British cars and Volvos. Basically if I remember right you take the cubic inch of your engine and divide by 2. then you take your redline limit, or max RPM and divide by 1728 and you get CFM you need. So a 4.0 is with a redline of 5000 rpms you get 350 CFM. Rochester’s 2G from Chevy 283 V8, Carter BBD from 318 V8, 2300 Holley from the 266 V8 are my picks for old style 2 barrel carbs. I have run all of these and work well on the 258's I have tried the Rochester Quadrajets, and Federal Mogul 4 barrel carbs. They are not my top pick to put on a 258 or smaller. They don't idle very well. Basicly I am saying anything from 350 to 400 CFM would be a good fitting carb. Now I really like Holly , but the Weber 38 DGAS 2 barrel Carb is very well made carb and you can find them very easy for jeeps. Engine size (in cu in) x Max RPM ÷ 3456 = 100% VE (cfm) Most street engines only ran 70-80% VE Too large or too small of a carb will hurt your engines performance. Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 14, 2016 Share Posted January 14, 2016 Engine size (in cu in) x Max RPM ÷ 3456 = 100% VE (cfm) Most street engines only ran 70-80% VE Too large or too small of a carb will hurt your engines performance. That is a different way to get the same number :) I have never used that way to get it, however now I know two ways to calculate it. Link to comment Share on other sites More sharing options...
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