Hello lads! I’m brand new to posting on the site but I’ve come here in the past to look at old threads to help troubleshoot. Anyways, I’ve got it in my head to four barrel swap my bone stock 1987 318. So I bought an old 340 intake off a 1970 dart I think, because I heard it would bolt on and work better than the stock 2 barrel system. Now I know port mismatch would be a slight issue but I’m not going for a race car here. Anyways after I had cleaned up the intake I realized my current two barrel intake had a lot more sensors and stuff like that. So now I’m confused as to how I’m gonna get it to work. I assume some are for emissions and stuff? Which I’m completely fine on doing away with. Would I need to change my ignition system or anything? I’m not very knowledgeable on engines just yet but any help or advice would be very much appreciated. Thanks!
Need advice for 340 intake swap
- Thread starter brophy
- Start date
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Professor Fate
Push the button, Max...
Is this in a truck or a passenger car?
Does the engine (the air cleaner in particular) look like this?
If it does, you're in for a lot more work than a simple manifold swap. That's a second generation (post Lean-Burn, but similar) engine control system, which utilizes feedback signals from the carburetor for fuel management and a locked distributor that relies on the computer for an advance signal (note the vacuum advance can on the air cleaner mounted engine controller).
You will need to change out the ignition and do a fair bit of rewiring in order to eliminate the rudimentary computer system and get the engine controls and some of the instrument panel warning lights and/or gauges to function, as well as deleting some of the pollution controls which will be inoperative once the computer is eliminated. And honestly, I forget if this iteration of computer controlled the charging system or not; so you may also need to wire in an electronic voltage regulator circuit with no computer.
If you're talking about a truck, much of this may not apply (depending on the model/ weight rating), and may lend itself to this swap a little more easily.
Does the engine (the air cleaner in particular) look like this?
If it does, you're in for a lot more work than a simple manifold swap. That's a second generation (post Lean-Burn, but similar) engine control system, which utilizes feedback signals from the carburetor for fuel management and a locked distributor that relies on the computer for an advance signal (note the vacuum advance can on the air cleaner mounted engine controller).
You will need to change out the ignition and do a fair bit of rewiring in order to eliminate the rudimentary computer system and get the engine controls and some of the instrument panel warning lights and/or gauges to function, as well as deleting some of the pollution controls which will be inoperative once the computer is eliminated. And honestly, I forget if this iteration of computer controlled the charging system or not; so you may also need to wire in an electronic voltage regulator circuit with no computer.
If you're talking about a truck, much of this may not apply (depending on the model/ weight rating), and may lend itself to this swap a little more easily.
Do you have emission testing? If so that would be a problem. Here in NY 20 year old vehicles aren't tested for emissions. Sometimes things might not be able to be done to our cars.
It’s in a D100. Looking at my air cleaner I see nothing hooked up to it like that. I’ll try and provide a picture of the engine bay when I get off work later. But I know I don’t have anything like that on the cleaner. Just the extra sensors and stuff that hook up to the intake manifold, but I have no idea where they lead or anything like that…
No I don’t thankfully, I think it was stopped in 2019 or around that time.
The port mismatch is much ado about nothing. Ma Mopar herself build millions of 318 engines right from the factory with big port intake manifolds atop "mismatched" small port heads, so they must notta thought too much of it.
Ya, we'll need some photos so we can see what your up against as far as sensors and such. I usually end up with a whole pile of important looking parts and just a few lines and wires.
Alright great because many people have told me that it will totally kill performance. But if I’m currently running the 2 barrel intake, a 4 barrel has to be better regardless of port size mismatching right?
Alright will do!
Yup, it won't hurt a thing.
Dartswinger70
Well-Known Member
I imagine you could nix all that sensor stuff and just wire up an ignition system and a 4 barrel etc. You could c9onvert the whole thing like converting from points to electronic ignition etc.
If your truck is auto you'll probably need a Lokar cable for the tranny.
Doesn't an 87 model have an ECM and TBI?
If he's converting to a 4bbl, he'll get rid of the ECM and the TBI.
Take the air cleaner off and lets get a lookie loo at what's under there
MOPAROFFICIAL
If it has tits, it's a liabilititty.
Is there a vac advance on the distributor?
If so, its not lean burn.
Also, the air cleaner would have a box on it with wires and vac line.
Looks like you have a egr setup.
If so, its not lean burn.
Also, the air cleaner would have a box on it with wires and vac line.
Looks like you have a egr setup.
No, I thought he'd bolt the carb on top of the TBI.
B3422w5
Well-Known Member
I wouldn’t even bother. If it don’t stink, don’t stir it. I doubt on a bone stock 318 it’s going to make a significant difference by itself
Ah. that's right. Mopar was a pioneer with the Lean Burn system.
MOPAROFFICIAL
If it has tits, it's a liabilititty.
Ingenious, that way he'll have a backup system of one fails ;)
Nope you ain't dumb. That's a carburetor.
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