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Carter BBS Carbureetor.
https://mail.slantsix.org/forum/viewtopic.php?t=68284		 Page 1 of 1
Author:  61 Val Jack [ Mon Jul 14, 2025 3:28 am ]
Post subject:  Carter BBS Carbureetor.
Hi there. My first time posting. I have a 61 Valiant V100 that I just bought about a month ago. I have done a lot of work on it and almost all of the work was because someone had hands on it. My current issue is the BBS Carburetor. It seemed to be flooding out after running the engine making it hard to start afterwards. I got a rebuild kit and took the carb apart. First obvious thing was the accelerator pump was missing the leather plunger from the pump. I proceeded to install the new parts, needle and seat was my main objective along with the accelerator pump. I still have gas running into my carburetor, landing on the throttle plate and running out of the throttle shaft and down the throat. (the kit did not have an instruction sheet but I was going by my factory service manual. I later pulled up the service sheet online. It states that the tab on the float has to be 90 degrees with the needle. I will be going back inside today to see if that might be my problem. All my 50 years of working on cars, and being a pretty decent carb guy, I never ran into that being an issue. Just wondering if anyone else ever run into this issue. Thanks
Author:  SlantSixDan [ Mon Jul 14, 2025 1:48 pm ]
Post subject:  Re: Carter BBS Carbureetor.
Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. You will likely need more comprehensive refurbishment on that carburetor than can be done with a parts-store-"quality" minimal gasket kit; get a full, proper kit from www.thecarburetorshop.com .

Tune-up parts and technique suggestions in this post.
Author:  61 Val Jack [ Tue Jul 15, 2025 3:42 am ]
Post subject:  Re: Carter BBS Carbureetor.
Dan, thank you so much for the information and links. I went to this link, Carter BBS operation and repair manual, and got a very good understanding of the idle circuit. There is definitely a few things I want to go back to check. I feel that I have 2 problems. There must be a blockage somewhere in the idle circuit. Also had a problem with the needle valve not seating properly. With both problems, the overflow of fuel into the barrel was actually making it idle well, but dumping fuel into the barrel when the engine would shut off. I have the needle valve sealing as it should now, cutting off the overflow of fuel to the bowl. Now it is idling too lean. So lean that I cannot richen it with the mixture screw. So, there has to be a fuel restriction or blockage in the idle circuit. I will be an expert by the time I am done...LOL. I did order a factory rebuilt unit from ebay at a decent price. So, I do have a backup plan. Thanks again.
Author:  mcnoople [ Tue Jul 15, 2025 5:59 am ]
Post subject:  Re: Carter BBS Carbureetor.
Quote:
I did order a factory rebuilt unit from ebay at a decent price. So, I do have a backup plan. Thanks again.
Sometimes that is the equivalent of cocking the gun and pointing it at your foot. Remans in recent years have become rebuildable cores at best and shiny scrap metal in worst case situations. From time to time people do luck out and get a properly rebuilt and adjusted unit.

If it is lean you might have a vacuum leak somewhere.
Author:  61 Val Jack [ Tue Jul 15, 2025 6:16 am ]
Post subject:  Re: Carter BBS Carbureetor.
Spraying carb cleaner around the throttle shaft seems to be the only leak I can find. It really seems like more fuel is the answer. In the manual link, they talk a lot about the importance of the float bowl vent. I have to tell you that I did nothing in that area and the little cover is just laying there. It looks like it is to be open a little in idle situations. I guess if the bowl is not properly vented, it may not allow fuel to flow properly. I have what I need to make it work and do proper adjustments. I think I will start there. I know that rebuilt units are a crap shoot. At least, I will have more parts if it does not work out. It was advertised as factory rebuild from many years ago and was part of an old parts house buyout. Fingers crossed.
Author:  SlantSixDan [ Tue Jul 15, 2025 10:55 am ]
Post subject:  Re: Carter BBS Carbureetor.
Quote:
dumping fuel into the barrel when the engine would shut off.
Do the Fuel line mod
Quote:
I did order a factory rebuilt unit
These usually don't work well at all.
Author:  61 Val Jack [ Tue Jul 15, 2025 6:35 pm ]
Post subject:  Re: Carter BBS Carbureetor.
I have the dumping fuel issue solved. Going to let good enough alone till the replacement carb gets here. Then, it will be time to start over.
Author:  mcnoople [ Wed Jul 16, 2025 5:52 am ]
Post subject:  Re: Carter BBS Carbureetor.
Quote:
I have the dumping fuel issue solved. Going to let good enough alone till the replacement carb gets here. Then, it will be time to start over.
what did you find?
Author:  61 Val Jack [ Thu Jul 17, 2025 4:10 am ]
Post subject:  Re: Carter BBS Carbureetor.
I believe that float level along with the new needle valve solved the flooding after I shut it off problem. I have been tweeking with float level by turning the needle seat in and out and I found it's happy spot for quitting the flooding. But it idles like crap and spits fuel out the tail pipe at idle. (engine runs great once I get it up out of the idle circuit) I was talking to a friend last evening who has more experience than I when it comes to carbs. He said that for some reason the slant six makes a lot of vacuum, and in some instances, if the throttle has to be open too wide to make it idle, it pulls too much fuel through the slot at the throttle plate. He said to try drilling a hole (start with less than 1/8") in the throttle plate near the fuel feed slot. This will raise the rpm with the plate more closed. Thus sending less air past the slot. After thinking all evening about this, it makes perfect sense. As of right now, I have the idle screw all the way in just to make 600 rpm. I have nothing to loose, and it is easy enough to close the hole if I need to. I will post the results. This carb is a real junker. The 4 long screws have been over tightened for many years and has pulled the back half of it into a big frown. It really will be a miracle if I get much more time out of this unit. At least it does not leak.
Author:  61 Val Jack [ Thu Jul 17, 2025 7:24 am ]
Post subject:  Re: Carter BBS Carbureetor.
Okay, I am finally getting somewhere. I drilled a 3/32" hole in my throttle blade, on the side near the mixture screw. This allowed me to take 3 turns out of the throttle idle screw and made the throttle blade close a little bit. The engine will now idle almost perfectly. Not today, but probably tomorrow, I will go up to 7/64". Only because I feel I can go just a little more to get it perfect. I can now let it idle without burning my eyes, it shuts off well, it is not flooding, and it restarts as it should. Now I got to get that oil changed since so much gas has made it past the rings.
Author:  SlantSixDan [ Thu Jul 17, 2025 3:33 pm ]
Post subject:  Re: Carter BBS Carbureetor.
Oh, boy.

When a car part isn't working correctly, it's because something's wrong with it, not because nobody has yet come along to brutalize it by drilling holes that aren't supposed to be there. It's nice that you've got it idling better, but this will have come at the expense of something else you haven't yet discovered, some other aspect of carburetion.
Author:  61 Val Jack [ Fri Jul 18, 2025 3:44 am ]
Post subject:  Re: Carter BBS Carbureetor.
Drilling the throttle blade has been a trick for many years on engines with large cams. It is done so the car will idle well without dumping an overload of fuel in the engine by having the blade open too far past the fuel slot in the lower part of the barrel. One would think there is a problem somewhere else and this is a compensation for it on a stock cam slant six. Other than dumping fuel when shut off, the engine was running pretty good before I rebuilt the carb. After I did so, the idle went to crap. I got a ton of dirt out of the carb and the needle valve had visible wear. Also the cup was missing off of the accelerator pump. The car ran pretty good considering these problems. It is doubtful I will get to the bottom of the hidden problem. Important part, the hole drilled has no effect on anything once the engine gets in the run circuit. It only effects the idle circuit. I would bet there are thousands of BBS slant sixes out there that has an idle problem, and the people are living with it or got the idle cranked up to compensate for it. The idle circuit is pretty simple, and the only thing I can think of is the fuel passage is worn and letting too much fuel travel into the barrel.
Author:  SlantSixDan [ Fri Jul 18, 2025 10:02 am ]
Post subject:  Re: Carter BBS Carbureetor.
'K, dude, you went from having zero idea how a BBS works to being an expert in secret carburetor tricks in record time. Have fun!
Author:  61 Val Jack [ Sat Jul 19, 2025 3:07 am ]
Post subject:  Re: Carter BBS Carbureetor.
That's sort of true...LOL. I have worked with Edelbrock and Carter AVS, AFB all my adult life. (I'll be 70 soon) Simple as simple gets. Without a doubt, when these units get to be 60+ years old, and has had many hands inside them, Resourcefulness comes into play. The throttle shaft leaks a little and ports and threads wear out. I won't say that I got it running perfect, but it is drivable until I get my hands on the one I got on the way. (Seller just got it sent) I want to thank you for all of the encouragement. This little 61 Valiant is just like the one I had in 1972 as my first car. This car is 10 times better than the one I had back then. The little 170 has so much power, I would never dream of changing it to a V8. If I have the need for more power, I will jump in my 1970 Challenger with the 440. I am sure somewhere down the road I will need more help. This will be my "Go To Place" to find it.
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