2 barrel , 4 barrel, whose got the answer?

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palani

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bear with me please: 1983 318 stock, in a b250 van (concversion). because it is a lean burn (that doesnt work any more) it ios being converted to a hei ignition system with vacuum advance ( the gm hei module). the present carb (2 barrel) doesnt have a vacuum port to run the vacuum advance. so the coice is to either replace the 2 barrel (2280 holley or carter bbd), pull manifoold and change to a 4 barrel, or some combination. in a ideal worl i would change to a spreadbore and run either a thermoquad or quadrajet (550 cfm). since i havent started taking anything apart im open right now to considerations. this will be low rpm use (4500), hoping to gain better mileage (arent we all) as well as more power.
to summereize.\, a stockk two barrel on stock two barrel manifold, a four barrel on that 2 barrel manifold, or a 4 barrel with a 4 barrel manifold.
interested in your thoughts if you please. i also appreciate your time in responding, thanks
palani
 
Well these are my thoughts, its a van so I am assuming cruising and hauling, but I have seen a Dodge van or three with a 440 in it in my day so performance I get it. The 318 , try both carburetors see which one performs and record gas mileage etc. 318 is the economy utility V8 so either way you may be surprised. Ill add that with a 318putting on an induction system also needs an ehaust sytem to go with it then after that the bottleneck is the heads. Slapping a 4 barrel on a 2 barrel van and doing nothing else may just result in poor mpg IMO
 
In my opinion, a properly sized four barrel has no downsides unless you're on the throttle all the time. I would get a cheap, low performance four barrel intake and stick a 600cfm carb on top. Call it a day after that.
 
My best mileage ever on my 340 was with a stock manifold and Thermoquad. It also hauled ***….

1735066648828.png
 
palani said:
bear with me please: 1983 318 stock, in a b250 van (concversion). because it is a lean burn (that doesnt work any more) it ios being converted to a hei ignition system with vacuum advance ( the gm hei module). the present carb (2 barrel) doesnt have a vacuum port to run the vacuum advance. so the coice is to either replace the 2 barrel (2280 holley or carter bbd), pull manifoold and change to a 4 barrel, or some combination. in a ideal worl i would change to a spreadbore and run either a thermoquad or quadrajet (550 cfm). since i havent started taking anything apart im open right now to considerations. this will be low rpm use (4500), hoping to gain better mileage (arent we all) as well as more power.
to summereize.\, a stockk two barrel on stock two barrel manifold, a four barrel on that 2 barrel manifold, or a 4 barrel with a 4 barrel manifold.
interested in your thoughts if you please. i also appreciate your time in responding, thanks
palani
Click to expand...
  • I wouldn't use the lean burn carb. A 2bbl is very easy and cheap to get, even new. So the 2bbl is a great option. No changing intakes, and the linkage should work direct.
  • 4bbl is a great choice also. You'll need the carb, intake, gaskets, air cleaner, and work with the linkage. Kickdown linkage is a must on these auto's or you'll burn them up.
  • The best way to hook up HEI, and how I did it on my van is in the video. GET a COIL that will work without the ballast.
 
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AJ/FormS said:
I would just punch a hole in the side of the current 2bbl at the appropriate place, slide in a brass tube, and badabing there is your sparkport.
Click to expand...
This if you just want to get it running and driving.
OR, Put a want ad for a Carter BBD 318 vintage 67-70.
I'm sure some member has leftovers from a 2 to 4 barrel swap.
 
palani said:
bear with me please: 1983 318 stock, in a b250 van (concversion). because it is a lean burn (that doesnt work any more) it ios being converted to a hei ignition system with vacuum advance ( the gm hei module). the present carb (2 barrel) doesnt have a vacuum port to run the vacuum advance. so the coice is to either replace the 2 barrel (2280 holley or carter bbd), pull manifoold and change to a 4 barrel, or some combination. in a ideal worl i would change to a spreadbore and run either a thermoquad or quadrajet (550 cfm). since i havent started taking anything apart im open right now to considerations. this will be low rpm use (4500), hoping to gain better mileage (arent we all) as well as more power.
to summereize.\, a stockk two barrel on stock two barrel manifold, a four barrel on that 2 barrel manifold, or a 4 barrel with a 4 barrel manifold.
interested in your thoughts if you please. i also appreciate your time in responding, thanks
palani
Click to expand...

What I have done in the past with the leanburn swaps is;


Edelbrock 600cfm electric choke
Edelbrock throttle adapter
OEM (or open) air cleaner,
OEM or Edelbrock intake manifold
OEM or a MoPar Performenace vacuum advance distributor
MoPar Chrome ignition box though any would do well dept the orange ignition box from MoPar. Orange box ignitions from Mancini will do very well.

This is the basic package for the double conversion to move away from the leanburn systems that most always fail and the 2 to 4 barrel conversions.

A wire tap or splice will probably have to be done to use for the electrical choke connection. The auto parts store has these.

The linkage to the transmission will need to be adjusted. A simple nut, bolt and a pair of washers installed in the linkage will work just fine. The difference between the 2 & 4 barrel linkage is off just a little bit BUT will be disastrous if not addressed and reworked.

Sometimes, the carb to intake may need an adapter plate to ether or both help seal the carb to the intake and or raise it up a smidge to clear the intake. Since you will check if this issue is present before you proceed to the swap, this will be an easy thing to do.

This is an easy to do swap and adjustment on the transmission linkage for a great operating transmission. It is NOT HARD TO DO.

Keeping the two barrel carb you have now is st drilling a hole where it needs to be to add a vacuum port.
 
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Stick with the 2bbl . The throttle pressure for a 2bbl will be easy hook up. 4bbl without parts will be a nightmare. Just a thought for the transition to go smooth
 
Oldmanmopar said:
Stick with the 2bbl . The throttle pressure for a 2bbl will be easy hook up. 4bbl without parts will be a nightmare. Just a thought for the transition to go smooth
Click to expand...
I disagree with the “Nightmare” part. The only item not so quickly orders me from, let’s say Summit racing is the nut, bolt and the pair of washers. A quick trip to the local hardware store is all it takes.
 
I managed to convert a two barrel kickdown linkage to the Holley 4150 on my 318 car back when I was only 18. It's not too hard to do if you have a bit of mechanical knowhow.

The hardest part in my opinion is properly hooking up your throttle cable. You tend to have to clamp it the cable into the bracket on the sleeve, which tends to cause problems. That being said, my 71 Satellite Sebring has been driven like that for the past 6 years and hasn't broken the cable yet.
 
wow, thanks for all the replies! I usually hang out over at vanning.com, was doing a internet search for the carb and came across you folks. glad i found you, feally. so to go a little deeper, i will most likely keep the lean burn in the van but not hooked up. at least not until i get some miles on it with the new system. Thje ignoition chang im doing is going from a double pickup to a single pickup, hence the need for the vacuum advance. The low cost way to do hei on these (and others) is to pickup saiid distributer, using a gm hei to be the “box” the trigger if you will.. Ill put the hei module right uinder and con nected to the dizzy, using it asa a heat sink wwhile minimizing wire length. I went with a high output coil also. I think its alot like what “318will run” suggests. Ive been looking for that carb about 2 months right now. If someone has one that would be super. I can wait for the 4 barrel at a later time. Why the 4 barrel? esp a thermoquad or quadrajet? smaller primaries (than 2 barrell) so if you keep yoiur foot out of it it will be more econ. Back in the day i had a 74 dodge with 318, i got 15 with the ac on..with the ac off , on cruise and with fairing i got 18. which is what started me down this rabbit hole..(getting 10 right now). yes it runs but it is hotwired across, batteryh to coil for starting, once started will run but… need this to be reliable.
so thanks alot, ill trty putting a wanted add up
 
I have a great 4 bbl intake that would be perfect for your application... An offenhauser dual port dual plane intake for a spread bore... I will have to find it and post pictures....
 
yes please! I am looking for the 2 barrel but it would be great to do this all one time. let me kknow pleasew. and just a fyi, im not one to check every hour, more likely perhaps once a day.
palani
 
Oldmanmopar said:
Stick with the 2bbl . The throttle pressure for a 2bbl will be easy hook up. 4bbl without parts will be a nightmare. Just a thought for the transition to go smooth
Click to expand...
I agree. at the minimum, the following parts are needed;

the 4bbl intake. If you have A/C that will need to be addressed.
the gaskets, sealers, etc. and a 4bbl choke
Likely the Valve Covers will need to be removed, so more gaskets.
the 4bbl throttle bracket,
the 4bbl front KD rod, and
the 4bbl throttle cable. PLUS
the 4bbl air-filter housing, with filter. and
a new fabricated hard fuel-line down to the pump.
And maybe some hardware.
and maybe an oil/filter change afterwards.


Some of this stuff can be fudged, but if you do it wrong;
what if the throttle sticks at WOT, then what?
Or if the KD does not function correctly and the trans burns up, then what?

I agree that the LB carb is lean. and they are PITA to get working half-decent, therefore;
I agree with swapping to an older carb.
 
Pretty far reach with the what if’s.
The list of specific 4bbl items can be used if he wants but it’s not a need.
Looking and having the correct parts is a plus but not needed.
 
palani said:
bear with me please: 1983 318 stock, in a b250 van (concversion). because it is a lean burn (that doesnt work any more) it ios being converted to a hei ignition system with vacuum advance ( the gm hei module). the present carb (2 barrel) doesnt have a vacuum port to run the vacuum advance. so the coice is to either replace the 2 barrel (2280 holley or carter bbd), pull manifoold and change to a 4 barrel, or some combination. in a ideal worl i would change to a spreadbore and run either a thermoquad or quadrajet (550 cfm). since i havent started taking anything apart im open right now to considerations. this will be low rpm use (4500), hoping to gain better mileage (arent we all) as well as more power.
to summereize.\, a stockk two barrel on stock two barrel manifold, a four barrel on that 2 barrel manifold, or a 4 barrel with a 4 barrel manifold.
interested in your thoughts if you please. i also appreciate your time in responding, thanks
palani
Click to expand...

my thoughts are to KISS on the whole thing. you already have the pigtail/whip for the electronic ignition, why not just get a stock electronic ignition distributor (non lean burn edition) and snap that puppy in. then just plop on a carter BBD and be done with it. it's basically factory, you'll need to modify practically nothing. all of that stuff is cheap and widely available.

going from a 2bbl to a 4bbl will net you more power but likely at the expense of fuel mileage. and the power may not be where it is most useful or useable for your application. i'll agree a dual plane with a small square bore or a spread bore tuned in nicely is a hard combo to beat, but you're gonna have to work to get those mpg numbers. also, i wouldn't put a 4bbl on a 2bbl manifold; except for rare instances it's just a solution to a problem that nobody really has.
 
My only rebuttal to the prior comment is in reference to the mpg difference between a two barrel and four barrel. A performance oriented carburetor will definitely be set to run rich out of the box, but a standard four barrel for street use is calibrated for good mileage and overall performance.

I've yet to have a negative opinion with the use of a four barrel. In fact, I saw an increase of 4 mpg from a cam and four barrel swap in a car I messed with back in 2017. I used a 486cfm Rochester for that car. It gave a small boost in performance and a significant boost in mileage. I still drive that car today, though it's unfortunately a Chevrolet...

In all, I would probably do everything that junkyardhero just said to do if it were I who was in your case. A good two barrel will be happy. The only negative is that the Carter BBD tends to leak from the throttle shaft. You'll have to be picky about your carburetor choice if you use one of those.
 
Here is my 318 2bbl taking on and beating the same van with a 4bbl and headers. A lot of how they run is how they are tuned.
 
junkyardhero said:
going from a 2bbl to a 4bbl will net you more power but likely at the expense of fuel mileage.
Click to expand...

As long as the go pedal isn’t pressed hard or often…… LOL

I seriously disagree! Big time. Here’s why;

A 600 cfm 4bbl carb is what I used in my ‘79-360/904/2.76 drivetrain in my Magnum w/235/60/15’s which returned 20 mpg. The mods to the car were as followed.
A OEM ‘‘72 trap door air cleaner w/K&N filter.
600 cfm Federal-Mougal (Edelbrock) electric choke emissions carb
OEM spreadbore 4bbl. intake
MP chrome box
(I later added a MSD6 - good for more mileage at slow speeds/rpms)
Junkyard distributor from a truck
Dual exhaust off of the exhaust manifolds @ 2-1/4 w/an H pipe.
Due to the laws of the time, a visual inspection was done yearly (N.Y.) which required the car to have catalytic converter(s), so twin high flow cars were used after the H pipe into Dynomax turbo mufflers exiting at the bumper.

As 318WR said, tunning the set up is key to how it runs, so, the car was subject to constant tuning between the distributor timing and jetting of the carb. Also pay attention to the pump shot amount. Use only as much as the engine needs. Jet it on the lean side. (Lean for winter. It’ll richer up slightly for the summer. Air molecule expansion, and contraction due to the temperatures.)

The laws at the time said the car must be running for the test on dyno rollers while have a tail pipe sniffer attached. The car passed for a late 80’s F.I. standard. There was zero lack of power, drivability and was used on an easy dozen trips from Long Island New York to Snellville Georgia, Richmond & Lynchburg Virgina.

Routinely, 20mpg was the average.

YRMV, the gear ratio and tire size are a big play in the mileage search.

Could I have done better? Probably so if I decide to use headers, some, deletion of the A/C, mechanical fan, better intake manifold, etc. I decided to use the KISS method for this daily driver as it was my only car. I seen no sense in dumping extra money into it with minor advances in power and mileage. I was using it daily as my only car so messing with it further did ‘t really seem worthy to me.

Keeping your foot out of it will net good mileage results.
Sometimes, depending on the 2bbl, the 4bbl can have smaller primaries.
 
junkyardhero said:
my thoughts are to KISS on the whole thing. you already have the pigtail/whip for the electronic ignition, why not just get a stock electronic ignition distributor (non lean burn edition) and snap that puppy in. then just plop on a carter BBD and be done with it. it's basically factory, you'll need to modify practically nothing. all of that stuff is cheap and widely available.

going from a 2bbl to a 4bbl will net you more power but likely at the expense of fuel mileage. and the power may not be where it is most useful or useable for your application. i'll agree a dual plane with a small square bore or a spread bore tuned in nicely is a hard combo to beat, but you're gonna have to work to get those mpg numbers. also, i wouldn't put a 4bbl on a 2bbl manifold; except for rare instances it's just a solution to a problem that nobody really has.
Click to expand...
the problem of going with a mopar stock dizzy is that ballast resistor . by doing what
im doing i get rid of that (the resistor), can open the plug gap to around .045, better more complete burn (higher voltage). so right now i got the dizzy (vac advance) and the hei module, high power coil, etc. just missing the carb. from some of the folks on here ive found rebuilders from 15-35 dollars. like anyone who grew up on the muscle cars, those 4 barrels are soo nice. i do agree that it would be better to just do the 2 barrel . but i wouldnt mind having the manifold and carb on the shelf.(i got a 518 trans in the barn, which is from 87 (i think) has a overdrive). just thinking ahead.
but i did think like what your saying and KISS is much better. and in case anyone is interested, i did get the service manual and went thru the entire lean burn system, only thing that raised any flags was a 1/2 volt drop at the coil. which for some reason wouldnt alloqw the engine to start. wierd. but what it is.
thanks
 
this is great! glad i found you all. so the plan right now is to find a good carter bbd, rebujild it and start changing stuff over. Ill try to keep you all in the loop but i move pretty slow now (74) so bear with me, i do want to track the mileage and doing it this way will allow me to do just that. i still want to find a thermoquad or quadra and a manifold, maybe try that after i get some numbers. wrenching is fun when its not your primary job, i like doing.
for the numbers people, this van has 3.55 rear, some of the widest tires front and back, which works against mei know. supposedly it has only 43000 miles but i think more like 143000. picked it up for 3500, tires blew after 100 miles (cause they were over 20 years old) anyway rebuilt the front suspension, rotoar , calipiers, shocks rear brake shoes, starter, all the vac hoses, et, etc. if i forgot anything you might want to know just ask
thanks you all
 
palani said:
this is great! glad i found you all. so the plan right now is to find a good carter bbd, rebujild it and start changing stuff over. Ill try to keep you all in the loop but i move pretty slow now (74) so bear with me, i do want to track the mileage and doing it this way will allow me to do just that. i still want to find a thermoquad or quadra and a manifold, maybe try that after i get some numbers. wrenching is fun when its not your primary job, i like doing.
for the numbers people, this van has 3.55 rear, some of the widest tires front and back, which works against mei know. supposedly it has only 43000 miles but i think more like 143000. picked it up for 3500, tires blew after 100 miles (cause they were over 20 years old) anyway rebuilt the front suspension, rotoar , calipiers, shocks rear brake shoes, starter, all the vac hoses, et, etc. if i forgot anything you might want to know just ask
thanks you all
Click to expand...

This sounds like a fun project to play with. I hear ya on moving slow. While I am young at 58, persistent back problems are painful and limiting. Also, I’m no Rockefeller either.

3.55’s are tough to get great mileage from but for where I am at, mid Florida, speed limits around the area are normally + or - 10 mph of 45, 45 being the average. So my 3.55’s in my Magnum currently work out pretty good for around here. RPM’s are low due to the average posted speed limits.

And, I agree. I was a heavy mechanic for decades. Had a side biz as the neighborhood Mr. fix-it guy. Always in grease and oil. Everyone’s car runs and works great except mine. Too tired to do anything on it and I never wanted to since I was doing it all the dang time.

You MAY want to contact Dana a member here that rebuilds carbs with a good positive response from members here. IDK his prices but his work is often made a bunch here pretty happy.

He may perhaps have the carb you’re looking for. Ask him. Might have some luck. Who knows?
 
palani said:
the problem of going with a mopar stock dizzy is that ballast resistor . by doing what
im doing i get rid of that (the resistor), can open the plug gap to around .045, better more complete burn (higher voltage). so right now i got the dizzy (vac advance) and the hei module, high power coil, etc. just missing the carb. from some of the folks on here ive found rebuilders from 15-35 dollars. like anyone who grew up on the muscle cars, those 4 barrels are soo nice. i do agree that it would be better to just do the 2 barrel . but i wouldnt mind having the manifold and carb on the shelf.(i got a 518 trans in the barn, which is from 87 (i think) has a overdrive). just thinking ahead.
but i did think like what your saying and KISS is much better. and in case anyone is interested, i did get the service manual and went thru the entire lean burn system, only thing that raised any flags was a 1/2 volt drop at the coil. which for some reason wouldnt alloqw the engine to start. wierd. but what it is.
thanks
Click to expand...
you seem to have made up your mind and i will not try and dissuade you.
 
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