So I just bought a 83 dodge truck. Has been overbored 0.60 but idled rough, and idled at 2 grand, got it home turned down idle to about 1 thousand. The motor isn't original for yr. But air cleaner has computer ? Is that a good thing? Being overbored do I need a double barrel carb or bigger single barrel, would that computer cause problems?

The computer on the air cleaner is an indication that either your truck or the vehicle the engine came from (if the previous owners didn't keep the air cleaner original to your truck) was equipped with some form the Chrysler's notorious "lean burn" ignition and/or fuel system. Beginning in the late 70s and continuing until the adoption of fuel injection across all models, Chrysler used a primitive computer controlled ignition and/or carburetor on some models. These systems could be only ignition controlled by the computer, only the carburetor controlled by the computer, or both ignition and carburetor controlled by the computer. These systems were notorious for poor idle quality and failure even when they were brand new. At this late date more often than not the computer or some other component of the system has failed and repairs are expensive and it is hard to find replacement parts.

Most people wind up removing the lean burn system and switching to a standard electronic ignition and non-computer controlled carburetor. Removing the lean burn system typically results in improved fuel economy, improved emissions performance, and improved driveabllity.

However, the facts that there is a computer on the engine and that someone has swapped engines in the truck means that your truck might just have an air cleaner off of a lean burn vehicle but that your truck actually has no lean burn system installed. You need to inspect your carburetor and your distributor to determine if you have any portion of a lean burn system installed.

The preferred replacement systems are HEI for the ignition and some form of single barrel non computerized carb such as the Holley 1920 or Holley 1945.
Need? No. Potential future upgrade, maybe, but get your truck running right with what it currently has before you go adding more variable into the mix.
Possibly, see above.

Pictures are always appreciated!

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Casually looking for a Clifford hyperpak intake for cheap.

Alright I'll check the distributer and take a few pics. There's definitely some pieces I don't recognize exhaust has extra hole right after manifold, thanks for the great response, so I possibly could/ will have to replace distributor, carb, air cleaner housing, and don't like the look of exhaust manifold.. my other is much less involved.

Does distributor have a vacuum advance can?
Yes = standard electronic non Lean Burn distributor.
No = lean burn device with no vacuum advance capability

Does carburetor have wires attached to selonoids, and throttle position sensor?
Yes = lean burn carburetor
No = most likely not lean burn, or it could be a striped down lean burn carb. Photos may be needed for good ID.

Hole in exhaust most likely an o2 sensor bung needed to communicate with feedback lean burn carburetor to control A/F mixture. Lean burn system when working correctly controls timing, air fuel mixture between 13.x: 1 and 19.x: 1 depending on engine load, rpm, coolant temperature, etc., and throttle position & movement. Eliminate any one of these sensors, or devices and the whole ball of wax malfunctions ad Reed explained previously.


My 2 cents:
Contrary to Reed’s assessment, lean burn contributed to poor fuel economy, it boosted fuel economy and was a fix for big displacement engine during one of the oil crisis of the seventies, and newly enacted government passenger car fuel consumption constraints.

We purchased new the first model Chrysler made utilizing lean burn technology, a ’76 Cordoba 400cid 4v. It would return 19 -19.5 mpg highway driving, and around 16 mpg in town. Compared to older similar displacement engines this was an improvement. By ’77 most of Chrysler’s engines were equipped with lean burn. Chrysler was the first company to use computer controlled engines, yes the analog control computer was crude by mid-eighties standards, but when it came out it was the latest and greatest, and Ford & GM soon followed with their own systems. This was a transitional time where the industry was being pushed to clean up emissions, and stumbled along with complicated highbred contraptions that did not work very well until EFI became industry standard.

Back in the seventies and early eighties computer technology was progressing at a blinding rate; every few months brought advancements doubling their computing capability & speed. Any computer produced in those days was an obsolete boat anchor in less than a year, and this is where Chrysler dropped the ball not upgrading their engine brain. By the time Ford and GM came out with their systems the industry had moved on by many generations, and GM & F began using devices advanced enough to be viable down the road into the mid-nineties.

The other end of the electronic engine management was the dealership’s service department to train technicians that could diagnose and repair these contraptions. Generally the work force was not quickly up to the task to understand this new method of engine management for several reasons, education being one, and the new trick for old dog problem being the other.

I know, because I dealt with these guys in the service department. 6 to 8K miles after we took delivery of car it developed a heavy knock at low speeds; between several dealerships on east coast and Chicago area their fix was to yank all lean burn system out to pulling engine to install new bearings. The fix was simple, grind off one of the corners of rotor button to reduce contact with distributor cap; it came from a factory bulletin listed in some article in an auto magazine that I had to point them to.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

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K I'll get a better pic of carb took air cleaner off but forgot pic, noticed today (think) the automatic choke cover is totally rusted, might not help anything. Went over checked it out more, battery's weak but it started once (think I was jumped it and starting fluid) ran for 20sec. I should've stayed on it but was concerned about over charging battery. It didn't start again.

There's definitely a lot more vacum lines, and between heat/rubber and sensors seems like a lot more to go wrong, or deal with troubleshooting. These "systems" did they work good, last or more desirable? Cuz seems like I'll be getting frustrated and going in circles. I got an extra older distributor from a slant 6 between that and a differn carb.. would it least run? What about the sensors (assuming they're there) do the effect wireing harness or? If the system was easy to diagnose performed better I'd try working with it.

That top image looks to be showing a fuel vapor trap. There should be a stick’ah somewhere under hood with vacuum line routing diagram.

Third Image of distributor is hard to tell, but looks to be missing vacuum advance pod, therefor it is a lean burn device.
Yup, it’s a bit of a mess, but can be sorted out, and avaluated.

There looks to be some hacking of the lean burn system, and any cracked or disconnected vacuum lines will cause faulty info to be sent to computer, and big drivability problems. To be able to understand and successfully properly sort out this mess one needs to have a factory service manual. I wouldn’t be surprised if all the sensors and related solenoids are in place, but not connected to computer correctly or are leaking or have bad electrical connection.
This will cause a hard starting problem and the colder it gets the worse it will become. A cold engine has to have a properly operating choke for easy cold starts.
Before any more starting attempts, fully charge battery, take it to a parts store along with alternator and voltage regulator, have them all tested, and proceed from there.

Trying to start engine with low battery will cause starter problems, and shorten battery life. Battery has to maintain full charge or it will lose its reserve storage capacity.
When new they worked fairly well if not monkeyed with, when aged, as you can see, the components degrade, and get hacked up by those that know not what they think they know. As I explained previously the lean burn on our Cordoba worked fine during the six years & 86k miles we had it.

Would a conversion to conventional vacuum advance distributor, non-lean burn carburetor, and GM HEI be more reliable today; Hell Yes because it is simple, and works flawlessly for years with no maintenance needed. Before ripping all that LB stuff out make sure your state EPA / auto inspection does not require all factory original pollution controls to be in place and working for your truck.

You could probably resurrect your lean burn system with FSM in hand, a mile or two of new vacuum hose, some wire, some cleaning, and a lot of luck. Once operational you will notice right away just how slow the computer reacts to tune engine as you drive; hey it is ancient technology. Back in the day LB was the cat’s ass compared to the 1973 & 1974 model year drivability problems of the day; that batch of iron leaving Detroit in those years was imposable to get to run right within newly enacted EPA rules.

Any or all of the sensors can be left in place to plug a hole if need be, but will not be connected to anything. You under hood wiring harness will look like any 1973 & up pre lean burn electronic ignition slant six configuration with the exception of GM HEI conversion if desired. You can also use orange box as well if you have one on hand to save a few bucks on GM parts.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Alright helps a lot! Emissions aren't an issue. I'll take the electrical parts in, and deal with switching over distributor, and find a carb. Then I'll remove that canister and all unneeded vacume lines. Cut sensors and fix auto choke. Gotta look at exhaust manifold, got an extra outlet to bad can't make it an "e cut"

Woah, slow down. WJAJR, isn't 100% right on what he says.

THe lean burn system often didn't work right when new and parts are hard to find these days. Usually by now someone has already hacked up the system making repairs expensive and difficult. I have yet to own, encounter, or hear about a vehicle still equipped with a lean burn system that operated properly. Maybe WJAJR had one that worked back in the day when it was new, but nowadays these systems are more trouble than they are worth.

My point is that regardless of how the lean burn system functioned when new, at this late date it is almost guaranteed to be faulty and expensive and difficult to troubleshoot and repair. If you are dead set on keeping the lean burn you MUST get and USE the factory service manual for your exact vehicle. I still recommend you swap out the lean burn system.

The canister you posted a picture of if the charcoal canister which is a very useful thing to have. Yes, you could consider it to be an emissions item since what it does is trap the gasoline that evaporates out of the float bowl when the car is shut off. However, it then stores those vapors and reintroduces them back into the carburetor when the engine next starts. It saves you gas and makes starting the engine easier. It has no adverse effects on performance and really is a beneficial item to have.

Just because a carburetor has a solenoid mounted on the side DOESA NOT mean that you have a computer controlled carburetor. The idle stop solenoid WJAJR is referring to was used for several purposes, none of which were directly related to the lean burn system. Usually the idle stop solenoid was used on AC equipped vehicles to raise the idle a bit when the AC was engaged and the engine was idling. Some years also used the idle stop solenoid to hold the throttle open a bit on deceleration to prevent choking the motor.

If you have an idle stop solenoid, LEAVE IT ALONE AND HOOKED UP! Like the charcoal canister, the idle stop solenoid is a very beneficial item to have and serves a good purpose. Disabling it will just make your car perform worse.

To tell if your carburetor is computer controlled you have to look for wires that go into the float bowl through the upper casting in the carb body. The computer controlled a stepper motor inside the carb that metered fuel going through a jet on the floor of the carb. If you have wires disappearing INTO the carb (not just hooking to a device screwed to the side of the carb) then you have a computer controlled carb. FYI- the stepper motors in the carbs are no longer available new, which is one of the reasons why getting the lean burn system working is expensive and difficult.

You DO have a lean burn ignition system because the distributor has two plugs going to it. Only lean burn distributors had two pickups in the distributor.

The hole in the exhaust right after the manifold is a factory bung that may or may not have been a point of air injection depending on the emissions package of the vehicle when it was built. Some were built with that bung plugged from the factory, others had a pipe from the air pump injecting air there. It looks like your air pump is plumbed into that hole. Leave it be. THe AIR pump draws very little power form the engine and help clean up your exhaust.

On slant sixes the O2 sensor (when one was equipped) went into a hole on the backside of the exhaust manifold immediately above and inboard of the rear protruding portion of the heat riser flapper shaft.

I might be looking at it wrong, but it appears you already have a two barrel carburetor on your motor. The throttle return spring bracket bolted to your intake manifold is clearly the two barrel carburetor piece. Please post some pictures of your carburetor so we can help diagnose your choke and other carb-related issues.

Whatever you do, don't just start blindly cutting hoses and wires. Get a factory service manual and identify every hose and wire you are looking at so you know what you are doing. The lean burn wiring is integrated into a couple other systems so just cutting wires might lead to other problems.

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Casually looking for a Clifford hyperpak intake for cheap.

Alright ill slow down a bit, always hoping its easy not too surprised its not. Definetly possible I got a 2bbl on this "new" truck of mine. I'll get a few good pics of carb today. I'll work to look past the canister and extra exaust hole. It is equipped with ac, for now I'm leaving that too. I definetly got a vacume advance distributor, but gonna have to figure out the carb. Might have to buy used, junkyard or.. thought I had old carb off sl6 but not sure I'd recognize it, or it has auto choke anyway. Thanks for the insight learning everyday.

I didn't see any electrical connections going to carb could be wrong but just tons of vacume lines.. I can cut and plug unneeded ones. Think I'm almost ready to actually do some work.

You do, in fact, have a two barrel carburetor and it actually doesn't have too many lines going to it. I say rebuild the carb you have, check for wear around the throttle shaft, get the throttle shaft rebushed if necessary, and be happy that you appear to have a non-lean burn controlled carb. Are you sure you have a vacuum advance can on the side of the distributor? I can't see one in the pictures you posted and I don't see the vacuum hose that is supposed to go down to the distributor. I DO see two plugs coming out of the distributor body which mens it is a lean burn distributor.

I see that you don't have a kickdown linkage. Is this a manual transmission truck?

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Casually looking for a Clifford hyperpak intake for cheap.

Yea it is a 4 speed manual, and yea I'm not sure the distributer in it has any vacume line currently running to it but the extra one I have does have a hook up for one vacume line and an elec. Connection. Yea I'll try to switch it and dump computer check vacume lines and see how it does. I think. And yea rebuilding a carb isn't to hard or expensive, would be good to learn especially being an extra truck. Thanks I'll try getting motivated between rain showers

Well didn't take long for me to be lost again. A lot of vacume lines.. got a vacuum advance distributor installed, not sure timing is where it should be. But where do I get vacuum for timing off carb? I got a line going to emissions canister, at least one from fuel filter( fuel filter has 3 lines assume one in one out and a return). The carb has at least 2-3 other outlets not being used. Guess ill take more pics of exactly what I'm talking about. Do I need to worry about extra distr. Elec connection or two air cleaner(comp) elec. Connections? Think its a carter carb.