So what's the deal? Which carb is the right one?

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cruiser

cruiser

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MoBros and MoSis':
I'm rebuilding the slant six engine in my October of 1973 build date 1974 Duster 225 auto federal emissions non-a/c car. I have two carbs and am not sure which one is correct for my car. I've heard that both are correct, but I'm not sure and I could use your advice. The first three photos below are of what I believe is the correct carb for my car: a Holley 1945. This carb is the one shown in the fuel section of my FSM. Note the part number and date coding in the second photo - 3830402 dated 1624. The base has "Elkton 6609B" molded in it. I know this is not the original carb for the car due to the date code, but I think it's the correct one for my motor. The second five photos are of another carb that I acquired NOS. It looks different from the first carb, especially with that barrel thing projecting from the top (visible in the fourth photo). Note the part number and date code in the fourth photo. As you can see, the second carb has different vacuum fittings than the first, so it doesn't connect exactly to the existing vacuum hosing in my engine. In fact, the holes in the side of the second carb where the vacuum taps should be are filled in inside. You can see this in the fourth photo. So what gives? What is this second carb? Can I use it in my car? My FSM says nothing about this carb. Is it any better than my Holley 1945? How would I hook it up if the vacuum taps are missing and the holes in the carb body are filled in? The base of the second carb says "Elkton 2 12R 6223B". Any and all ideas welcome. Thanks!

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I'd put a Carter BBS on it and call it a day.
 
The 3870902 Holley carb was used on 75-77 dodge vans with 225 engine and automatic transmission.
3830402 is the correct carb for your 1974 duster with 225 engine.
 
RustyRatRod said:
I'd put a Carter BBS on it and call it a day.
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The "RIGHT" one is a carb that allows your newly rebuilt engine to run well, and provides seamless drivability... unless you are creating a museum piece..

The "original" carb looks to have been 'remanufactured'... if it runs ok then you are lucky and you can feel good that you have an original carb on your car... In fact it might run better than what an "original 1974 holley 1945" would .. as Uncle Dan has pointed out numerous times the early 1945's had problems which were updated and fixed over the production run

My vote is to use a BBS, but if it must be a 1945, use the one that still has the plating on it.. and NEVER send it out to be "Remanufactured"
 
Whichever one makes your engine run the best it can
 
There's not going to be a judge with a clipboard subtracting points because your car doesn't have a correctly-stamped carburetor. If it's a choice between those two carbs, here's 24 votes (both hands, both feet, all ten fingers, and all ten toes) for using the NOS Dodge van item, which will run much better than the 'remanufactured' '74-spec carb. As has been explained many times when you've asked, the first-year 1945 carbs were a half-baked mess with a long list of problems eventually fixed in later production, and 'remanufacturing' ruins even a good carb.
 
slantsixdan said:
There's not going to be a judge with a clipboard subtracting points because your car doesn't have a correctly-stamped carburetor. If it's a choice between those two carbs, here's 24 votes (both hands, both feet, all ten fingers, and all ten toes) for using the NOS Dodge van item, which will run much better than the 'remanufactured' '74-spec carb. As has been explained many times when you've asked, the first-year 1945 carbs were a half-baked mess with a long list of problems eventually fixed in later production, and 'remanufacturing' ruins even a good carb.
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Thanks, Dan. That sounds like great advice. My difficulty in using the 902 carb from the 75-77 model year is that it appears to not be a direct "plug and play" unit. For example, there are several more vacuum ports on the Holley 1945 than on the 902 unit. So I don't know what vacuum ports go where. And as I mentioned, some of the recesses on the 902 appear to be filled in. Very puzzling. Any ideas? Thanks.
 
Same casting used for carbs with/without external bowl vent, with/without cold idle secondary enrichment, and with/without other features. Don't worry about it. Hook up the hoses that your car has to the correct ports on the new carb, and cap the unused ports. Easy.
 
Back then many trucks and Vans had more lenient emissions specs than cars
 
volaredon said:
Back then many trucks and Vans had more lenient emissions specs than cars
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Thanks for the reply, Don. Here's where I'm at. In the first photo below, there is a filled in hole that looks like a dimple between the two screw holes on the left side of the carb. On my Holley 1945, there is a metal nipple in this spot, with a rubber vacuum hose attached to the nipple which supplies vacuum to the heated air snorkel door. But since this nipple doesn't exist on the 902 carb, where am I supposed to plug in the vacuum supply for the air door? On the right side of the carb (second photo) the lowermost of the three holes is where the charcoal canister line plugs in. But this carb has no nipple there. So would I somehow have to extract the nipple from my existing Holley 1945 carb and insert (screw? push?) this nipple into the new carb so that I could have the charcoal canister correctly hooked up?

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townsend said:
The 3870902 Holley carb was used on 75-77 dodge vans with 225 engine and automatic transmission.
3830402 is the correct carb for your 1974 duster with 225 engine.
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Thanks, townsend. Is this carb (3870902) also a Holley carb? If so, do you know the Holley model number? Thank you!
 
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cruiser said:
there is a filled in hole that looks like a dimple between the two screw holes on the left side of the carb. On my Holley 1945, there is a metal nipple in this spot, with a rubber vacuum hose attached to the nipple which supplies vacuum to the heated air snorkel door. But since this nipple doesn't exist on the 902 carb, where am I supposed to plug in the vacuum supply for the air door?
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That hose wants to see manifold vacuum. So you can tee it into the choke pull-off hose, or you can connect it to the vacuum tap on the rearmost intake manifold runner.

cruiser said:
On the right side of the carb (second photo) the lowermost of the three holes is where the charcoal canister line plugs in. But this carb has no nipple there.
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Just as well; do like this and you'll wind up better off—the stock '74 setup using the throttle plate as a halfassed purge valve was a cheap, nasty, halfassed way of doing it.

cruiser said:
So would I somehow have to extract the nipple from my existing Holley 1945 carb and insert (screw? push?) this nipple into the new carb
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Wouldn't work; unless the nipple was originally installed on this carb and has gone missing, the hole isn't drilled.
 
A little more info on the Holley 1945 from 1974.
Two 1945 carbs were used on 225 engines in 1974 without Calif. emission pkg. and with auto transmission.
3751424 - Holley R-6724A and 3830402 - Holley R-6938A.
Chrysler superseded the 3751424 to the 3830402 in mid 1974 model year.
 
slantsixdan said:
Same casting used for carbs with/without external bowl vent, with/without cold idle secondary enrichment, and with/without other features. Don't worry about it. Hook up the hoses that your car has to the correct ports on the new carb, and cap the unused ports. Easy.
Click to expand...
So what would be the harm if I simply capped the charcoal canister nipple where the canister-to-carb line goes? If I end up using the 902 carb (the NOS one that doesn't have an attachment for the vapor return system) that would effectively isolate the charcoal canister from the engine and eliminate a lot of underhood plumbing. What's the harm in this? Would a lot of gasoline accumulate in the canister?
 
cruiser said:
So what would be the harm if I simply capped the charcoal canister nipple where the canister-to-carb line goes? If I end up using the 902 carb (the NOS one that doesn't have an attachment for the vapor return system) that would effectively isolate the charcoal canister from the engine and eliminate a lot of underhood plumbing. What's the harm in this? Would a lot of gasoline accumulate in the canister?
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Go read the article I linked for you to learn why your idea is not a good one.
 
Cruiser, with all respect, I wouldn't worry about what is right. I'd just make it it run good. Those mid 70's cars were terrible. Make it run like a 60's- early 70's car and enjoy the fact that you made it run properly.
Also, I haven't read any of your previous posts. I hope I'm in proper context.
 
townsend said:
The 3870902 Holley carb was used on 75-77 dodge vans with 225 engine and automatic transmission.
3830402 is the correct carb for your 1974 duster with 225 engine.
Click to expand...
Thanks, townsend. Do you have the model number of the 3870902 Holley 1945 carb?
 
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