So here's the situation. I have this remanufactured BBS on my '66 225 Dart. I've put hundreds of miles on it and it seems to run pretty well other than two slight issues:

1. The exhaust always smells very rich despite any adjustments I make to the carb.

2. On hot starts, the throttle must be held wide open to start, even after short drives.

This seems to be a later BBS (I'm guessing from a '69+ truck since it has a choke cable bracket and no vacuum pulloff) I'm beginning to wonder if the bowl vent could be part of the problems. Or if it is missing parts or has just been assembled incorrectly. I've done some searching and can't seem to find another BBS with this setup. (See attachments below) They either have a "cap" that opens and closes with the accelerator pump, or a plastic vent tube on top of the bowl. So my main questions are, is this bowl vent setup correct for this era of BBS? And could an issue with this vent be attributing to my symptoms listed above? any insight would be appreciated!

Also this is my 1st post on the board, so hopefully I've done this right!

I am by no means a BBS expert, but I can make some general comments.

1. Have you owned cars from this era before? If so, have you owned them recently?

I ask this because the normal exhaust of a car from 50-60 years ago will smell rich compared to a modern car, and if you're not used to it, it might seem abnormal.

2. It's not unusual to have to start a hot engine with the pedal on the floor, and many of us had cars that were fine, but needed this throughout their entire lives.

3. Why did you install a reman. carb?
More importantly, did you keep the old one (especially if it could have credibly been the original)?
Remans tend to be crap, and you have no idea what sorts of parts are floating around inside there, or how they've been adjusted.

4. Bowl vent looks fine to me. What do you think is wrong with it, and why do you think it's a concern?

5. Do you have a copy of the factory service manual?
You need one.
If you don't have one, you can download one here.
Most of us also like having an actual, flesh-and-blood physical manual. There's one here for forty bucks, plus shipping, which seems high to me, but you can watch eBay and a cheaper one is bound to show up.

6. First thing if you suspect a reman. carb is running rich or lean, check and adjust the float level.

7. How do your spark plugs look? If they don't look rich, then you're not running rich (or weren't just before you last turned off the engine).

8. If you still have the old carburetor, why not rebuild it?
Others are likely to recommend fancy rebuild kits at twice the price, but I haven't yet had a problem with the old HyGrade Jiffy-Kits.
That being said, it's only an extra $20, so what the hell?
Get a float, too.

9. Good luck!

– Eric

First off: the problem you've noticed is real, not imaginary. You should not have to floor the accelerator to start the engine, except very occasionally under specific circumstances.

The cause of the problem—at least one of the causes—is there is no external bowl vent on your carb. There's meant to be a round metal disk atop the carburetor casting, with a slot through which the accelerator pump stem passes. There are three grooves on the stem. A hairpin clip is installed on one of the grooves—which one corresponds to which hole in the throttle lever contains the link to the accelerator pump lift lever—such that when the throttle closes and lifts up the stem, the disk is lifted up by the hairpin clip to provide the bowl's external vent.

Instead, the "remanufacturer" installed wrong parts—a plastic disk under the carburetor casting—such that there is never the intended atmospheric bowl vent at closed and near-closed throttle. This setup is appropriate only for '70-up California and '71-up 49-state/Canada BBS carburetors with a separate external bowl vent valve and a ducted bowl vent outlet, which your carb doesn't have.

The missing disk is identified here as "Bowl vent valve":
There's a little metal bushing/hat, the bowl vent valve seat/accelerator pump spring retainer, which goes at the top of the accelerator pump spring and protrudes upward through the carb casting, to give the disk (bowl vent valve) a uniform surface to seal on (it would not do so against the uneven top of the carb casting). The bushing, identified here as 24, is Walker part № 22-53; no idea if it's still available, but from your photos it looks like that part is present on your carb, so all you'd need is the disk.
There's no aftermarket coverage of the bowl vent valve disk, but it (with that seat/retainer bushing) was used on gazillions of BBS and BBD carburetors pre-'71, so you ought to be able to scare one up.

Fix this (all the way fixed; this will call for careful adjustment of the accelerator pump stroke and bowl vent opening per the service manual), double-check your float adjustment while the carb is apart (see here), and the problems should get a whole lot better. Yes, this means you'll be opening up your carburetor and will need a rebuild kit for it which contains good gaskets. Parts store kits are no damn good any more, when you can even get them. Go directly to The Carburetor Shop for a worthy kit. It'll cost more than parts store trinkets, and it'll be worth it. Since there's no longer a carb ID tag, you will have to specify a closest-guess carb (№ 4905s) to get a correct kit. Set the float to 7/32", using the correct gauge, per the procedure in the manual.

Do the Fuel line mod and the flooded-hot-start and gassy-smell problems will get better still.

The exhaust from an old car is going to smell dirty, because it is dirty. But there's dirty, and then there's dirty. You'll need to make sure the carburetor is adjusted correctly, and once you've got the obvious problems corrected, drive it and then pull at least some of the spark plugs to check for too-rich running indicated by black carbon on the working ends of the spark plugs. They should be somewhere in the grey/tan region with a correct mixture and no excessive oil consumption. If you're running rich despite correct carb adjustment, the carb might be jetted too rich. Of the uncountably many BBSs I've seen over the years, one sticks out in mind right now: a "remanufactured" item bought in the early '90s, which had had its step-up rod replaced by a piece of wire which looked like it came off the spool of wire used to make staples on the fly in high-volume photocopying machines. It was way too thin, so the carb ran way too rich. Another one that comes to mind was missing the rubber gasket at the bottom of the step-up piston well, so there was no seal to keep the piston sucked down under high-vacuum conditions, so the piston was up oftener than it should have been, which meant the step-up rod was up out of the jet, which meant the carb ran rich.

So, you might have some sleuthing to do. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. Related: Tune-up parts and technique suggestions in this post.

Oh, another thing: you mention this carb has a choke cable bracket and no choke pull-off. That means it is meant to be used with a manual choke control. There should also be a compound choke lever with a very long arm and a cable clamp at the end plus an overchoke-relief spring which allows the choke plate to move open even when the cable is fully pulled, and a smooth, stepless fast-idle cam with a hole, not a slot, for the link from the choke lever. If all of these parts are not present, then the carb is a mishmash of mismatched parts, and there'll be problems.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

You're the man, Dan! This is EXACTLY the info I was looking for. Thanks a ton!

The original carb was missing when I bought the car. My car has factory A/C and an auto trans, so I needed a carb compatible with the accelerator cable/kickdown linkage setup. I had a hard time finding a core to rebuild that wasn't seized solid, missing parts, or wrong for my application. I figured a reman was worth a shot, despite knowing the risks about spotty quality with them. Like I mentioned, this BBS has generally been pretty okay. I've put tons of miles on it and have been daily driving it as it is.

After reading through my factory service manual and other materials on the many BBS variants, I knew my carb had some goofy things going on. Obviously the bowl vent didn't seem right to me at all. And this is indeed a manual choke carb, but it has the stepped fast idle cam for an automatic choke. It looks identical to this carb https://nationalcarburetors.com/Dodge-C ... 1336453897 Same choke lever setup with the spring and bracket. For the time being, I just have my fast idle cam/rod removed and a cable for the choke butterfly. I just operate the butterfly with the cable and use the throttle pedal for my fast idle until it warms up. Not ideal, but I rarely drive in colder weather and it rarely has trouble on cold starts. Will probably try making my own smooth fast idle cam to work with this setup.

I've already done the fuel line mod outlined in the thread you linked. I'm also using the thick carb base gasket and the manifold heat valve in the exhaust is working. So I'm all good there!

Float setting is definitely on my list of things to check, but I hadn't considered the step up piston or metering rod. Are those supposed to be tapered on the ends like in an AFB/Edelbrock? I've got a Hygrade rebuild kit or two I picked up just in case at a swap meet. I'll take another look at the plugs when I get a chance and report back on those as well.

I've got some solid ideas of what to correct and look for now, so I really appreciate the help!

Sounds like you got at least mostly/partly lucky. I would have specced a BBS for a '71 Dart with 198 engine. Throttle hookup is compatible, automatic choke, too, etc, and that subfamily of the BBS is much smaller, so much less chance for a remanufacturer to throw together the wrong parts.
Yup, I agree. You could put the cam and link back on and just remember to step on the gas before you pull the choke knob.
Yup. Stepped, actually.
Gladly!

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.