Ron Luchene Posted November 4, 2010 Share Posted November 4, 2010 I rebuilt the Carter AFB on my 65' but am frustrated with the choke as the vacuum seems weak. I will be removing the carb tomorrow night to insure there are no blockages. A couple of questions.1. The stove pipe fits into the exhaust manifold. Where is it drawing air from?2. If I switch to an electric choke, does NAPA or anyone carry a kit specific to the AFB? I have read several posts online tonight and while the Edlbrock kit is readily available at Advance Auto and others, it seems a shame to pay $65 - $75 for a kit and throw half of the parts away.Any suggestions are welcome.Ron Link to comment Share on other sites More sharing options...
carbking Posted November 4, 2010 Share Posted November 4, 2010 The vacuum for the choke is supplied by the engine. If the vacuum is weak, either the engine is very tired, or the vacuum passage inside the choke housing is not clean (it is small and makes a couple of 90 degree bends).Electric chokes have been around since the 1930's. They do NOT work well on older cars with automatic transmissions.THE CARBURETOR SHOP / Automatic chokesCarter has sold electric chokes for the AFB beginning about 1974. I don't know if they are still available, as I won't sell them. Too many customers expect them to work!Jon. Link to comment Share on other sites More sharing options...
Ron Luchene Posted November 4, 2010 Author Share Posted November 4, 2010 Jon,I will check the choke housing tonight. I realize where the vacuum comes from but I am curious where it is drawing the air from. Where does the tube inside the exhaust manifold go? I would think it is fresh air since the exhaust gas would do damage over time.Ron Link to comment Share on other sites More sharing options...
RivNut Posted November 4, 2010 Share Posted November 4, 2010 At the top of your carburetor is a brass port on the passenger's side near the rear. A piece of vacuum hose runs from it to the bottom of the choke tube that's inside the passenger side of the exhaust manifold. That creates a clean / fresh air port for the air going to the choke housing.In the attached picture, it's a brass tube that exits the neck of the carburetor. It directly over the "Made in the USA" stamp on the body of the carb.Just make sure the hose has plenty of clearance as it goes around and over the exhaust manifold.Ed Link to comment Share on other sites More sharing options...
Ron Luchene Posted November 5, 2010 Author Share Posted November 5, 2010 Ed,Thanks for the explanation. The plot thickens a bit. On my car the port you are referring too is equipped with a rubber cap. I can't wait to get under the car to see what the bottom side of the exhaust manifold looks like. In addition, I guess I am drawing fresh air at this point since nothing is connected to the bottom of the exhaust manifold. More to follow...Thanks - Ron Link to comment Share on other sites More sharing options...
RivNut Posted November 5, 2010 Share Posted November 5, 2010 The tube from the carb's air horn ensures that the air moving through the choke's hot air tube is clean and that in turn keeps debris out of the hot air tube so it will function properly. There's no vacuum at the brass port so the rubber cap isn't really necessary. Hopefully you find that the hot air tube is clean and that there's enough of it remaining at the bottom that you can reattach a hose to it.Ed Link to comment Share on other sites More sharing options...
Ron Luchene Posted November 5, 2010 Author Share Posted November 5, 2010 I checked the manifold and the hot air tube is in good shape. It looks like I will need to insert some copper tubing or something to tie the hose to. Not sure why the choke hot air is coming from the rear port on the hot air tube as it seems it would make more sense for the choke to be connected to the hot air tub as it exits out the forward side of the exhaust manifold and the rear port connected to the brass port on the carburetor.Also, the exhaust manifold valve thermostat is rusted and stuck wide open. I assume that a working thermostat would allow the choke to open quicker but is it critical that I replace this valve? Link to comment Share on other sites More sharing options...
RivNut Posted November 6, 2010 Share Posted November 6, 2010 Using the top of the manifold for the hot air means that the hot air doesn't have to travel as far to get to the carb and a steel tube can be used. If it were coming from the bottom, you'd have a steel tube that would have to clear the manifold and in its longer journey, the air in the tube would have a tendency to cool.You're correct, with a non-functioning flapper, the air will take longer to heat up because the exhaust gasses can flow past the hot air tube much quicker and wouldn't have the tendency to heat the tube as much.Ed Link to comment Share on other sites More sharing options...
Ron Luchene Posted November 6, 2010 Author Share Posted November 6, 2010 Success!!! There was debri in the vacuum port for the Choke housing. I cleaned it out and installed the stove pipe and line from the carb down to the other port on the exhaust manifold. I let the car warm up for a few minutes and the choke opened about 50%. Took the car on a 10 mile drive and checked the choke again. Wide open!Thanks for your help guys! Link to comment Share on other sites More sharing options...
Jim Cannon Posted November 7, 2010 Share Posted November 7, 2010 Using the top of the manifold for the hot air means that the hot air doesn't have to travel as far to get to the carb and a steel tube can be used. If it were coming from the bottom, you'd have a steel tube that would have to clear the manifold and in its longer journey, the air in the tube would have a tendency to cool. The steel tube on my '63 has some kind of woven insulation tube slipped on it (see photo). This helps keep the air going to the choke hot on it's way up there, and helps protect other things from the hot steel tube (like vacuum hoses, spark plug wires, and mechanic's fingers). If you do not have this insulation, the Buick parts vendors sell one that you can slip over your tube (from the manifold end, when it is off of the car).On my '63, a second steel pipe runs down to the lower port. It comes part way up toward the carb and then the rubber hose connects to it and goes the rest of the way up to the brass port on the carb horn that Ed mentioned. I do not know about later years. See second photo (of a '63). They did not use rubber hose next to the exhaust manifold. Link to comment Share on other sites More sharing options...
RivNut Posted November 7, 2010 Share Posted November 7, 2010 Jim,It's great that you have a car that you can date the history of from day one. I think I've got a piece of pipe lying around that looks like the one that comes out of the bottom of the manifold; I've always wondered what it was for. :cool:Ed Link to comment Share on other sites More sharing options...
Ron Luchene Posted November 7, 2010 Author Share Posted November 7, 2010 I made one from brass tubing and without the photo for reference, I chose to wrap it around the exhaust manifold and then to the rear of the block. I connected the rubber hose there and then to the brass port at the top of the carb. I bought a Choke Stove Pipe repair kit from the local auto parts store for the tube to the choke. I had some woven insulation left over from the original stove pipe to the choke and used that to cover the line from the lower hole up to where the rubber hose attached. It looks good even though the lower line isn't routed in the same fashion as yours. I'm happy with the end result as I had just about settled on an electric choke and given up on the original design. Link to comment Share on other sites More sharing options...
Guest Rob J Posted November 18, 2011 Share Posted November 18, 2011 I know this is an old thread, but in case anybody needs the info, Cars, Inc. has a choke stove pipe kit to replace that often rusted and broken pipe that connects from the bottom of the passenger exhaust manifold up to the choke of the carb. It comes with new insulation wrapping as well. For the fresh air pipe that runs from the rear of the carb to the exhaust manifold, I just used a piece of brake line pipe, cut and bent to the length needed, as there are no fittings needed on this pipe. A small piece of rubber vac hose (approx 3-4 inches) connects to the rear brass fitting of the carb, then to the steel pipe, then the steel pipe simply inserts into a stainless steel nipple on the manifold. Often times, you'll have to remove the old rusted pipe still left in that fitting. Link to comment Share on other sites More sharing options...
DV8 Posted October 21, 2016 Share Posted October 21, 2016 I'm finally going to get my choke stove pipe system back to the way it should be. This thread has answered all of my questions except this one: How does the choke stove tube and the fresh air tube attach to the nipples on the manifold? Do the metal pipes just slip on? Is there a short piece of vacuum hose that connects them as such the fresh air tube to the carb? Been searching far and wide for a photo of the proper connection but can't find anything on the web or the service manual. Link to comment Share on other sites More sharing options...
1965rivgs Posted October 22, 2016 Share Posted October 22, 2016 The metal pipes just slip into the thru-tube in the manifold. Tom Link to comment Share on other sites More sharing options...
Chasander Posted October 22, 2016 Share Posted October 22, 2016 I am going to remove my passenger side exhaust manifold and try and clean out the "stove pipe". Looks like pipe material has broken off in it blocking the way to insert new pipe. Has anyone tried to lightly drill/ream out old pipe material without damaging the "stove". Inline tube sells a 2 pc. kit for a 63 that fits a Rochester. why would this be different than a Carter? I'm looking for some insight from forum if I'm going in wrong direction. Maybe I should be looking for a different manifold. I have a "Stove" but really don't know what it goes to. Wonder if its replace able? Thanks Chuck Link to comment Share on other sites More sharing options...
telriv Posted October 22, 2016 Share Posted October 22, 2016 Ron & Chasander, If you go to "search" & type in I want an "original" carb-1964 riviera All your questions will be answered. I still can't believe there have almost been 3600 views & NO ONE has sent any pics!!!!! Tom T. Link to comment Share on other sites More sharing options...
Rivman Posted October 22, 2016 Share Posted October 22, 2016 5 hours ago, Chasander said: Has anyone tried to lightly drill/ream out old pipe material without damaging the "stove". Thanks Chuck I was able to get to it with it on the car on my LX '65, with a 90* drill. I used a drill bit slightly smaller than the inside diameter of the pipe, got a straight start into it, and when it got part way through the old rusted pipe inside the tube let go and spun out. With it on the car it did drop down into the manifold pipe but I didn't think it would or could cause any harm. Link to comment Share on other sites More sharing options...
1965rivgs Posted October 22, 2016 Share Posted October 22, 2016 When drilling out the thru tube one must be careful not to go too deep. The fresh and hot air pipes do not insert into the thru pipe very far. There is a flat metal insert in the thru tube which looks like a twisted dipstick. This is designed to "twirl" the air flow thru the tube to maximize heat transfer by slowing the flow of air and keeping the air in the tube for a maximum mount of time. If one goes too deep with the drill bit, one will start getting into this insert. Tom Mooney Link to comment Share on other sites More sharing options...
PWB Posted October 22, 2016 Share Posted October 22, 2016 Curious - just when did automobile carbs start robbing heat from manifolds? Hmmmm Link to comment Share on other sites More sharing options...
telriv Posted October 23, 2016 Share Posted October 23, 2016 When they 1st. came out with auto chokes in the 30's. Link to comment Share on other sites More sharing options...
DV8 Posted December 31, 2016 Share Posted December 31, 2016 I just got around to pulling apart my choke housing, cleaning everything and replacing a few small parts. At first I wasn't getting any vacuum at the stove pipe inlet. I poked a wire brush deep down the hole well into the carb and managed to free up quite a bit of gunk. At that point not only was I still not getting vacuum, it was slightly blowing positive air. The vacuum gage was wiggling just around zero. I'm able to get a good vacuum level everywhere else on the carb where there should be vacuum but how is it even possible that I'm getting positive air at the stove pipe inlet? Link to comment Share on other sites More sharing options...
telriv Posted December 31, 2016 Share Posted December 31, 2016 The plate under the carb. is rotted out or missing. What you are getting is exhaust. That's why things are gummed up inside the vacuum ports. Link to comment Share on other sites More sharing options...
DV8 Posted January 1, 2017 Share Posted January 1, 2017 So just removing the carb, giving the underside channels a good once over with a wire brush and some carb cleaner and replacing the plates should correct it? Anything else anyone can think of? Link to comment Share on other sites More sharing options...
alini Posted January 1, 2017 Share Posted January 1, 2017 That is the basic repair, some of us have plugged the holes in the intake so the exhaust gases dont flow through the channel. Replacing the plate fixes the problem but in a few years it will get eaten away again. 1 Link to comment Share on other sites More sharing options...
DV8 Posted January 20, 2017 Share Posted January 20, 2017 OK so a lot of progress but still something in question. Here's what I just did: -Removed the carburetor -Cleaned all the gunk out of the exhaust channel in the manifold (There was quite a bit of gunk but very little corrosion) -Cleaned all contact surfaces with sandpaper, steel wool, carb cleaner etc. -New fiber gasket and steel plate -Remounted carb Started right up, choke opened in a few minutes and the engine runs smoother than I've ever heard it based on sound a feel. Here's my on question: After I let it warm up I still wasn't getting a vacuum reading at the choke stove pipe inlet. This time it wasn't blowing exhaust because I now have the steel plate where it should be, which is good but, still not pulling hot air from the stove pipe. Here's my thought: I didn't check it until it was warmed up and the choke was all the way open. Does that little piston valve inside the choke housing block the vacuum to the stove pipe once the choke is open? Therefore the only way to properly test the stove pipe inlet for vacuum is from a completely cold start during the first few minutes of the engine running? Link to comment Share on other sites More sharing options...
telriv Posted January 21, 2017 Share Posted January 21, 2017 When the choke housing was removed from the carb. did you notice a little black round o-ring??? That's the seal between the carb. & the choke housing. A NEW seal comes in the rebuild kit. This seal needs to be tight or you will lose some vacuum. What I usually do when I rebuild one of these AFB's is to take a very thin brass washer, or some thicker brass shim material, cut to the proper size & put a small hole in it & install it in the cavity of the carb. where the seal sits. This TIGHTENS the connection between the choke housing & the carb. for a better seal. Tom T. Link to comment Share on other sites More sharing options...
DV8 Posted January 21, 2017 Share Posted January 21, 2017 (edited) Yes, the small rubber gasket was there and practically crumbled as I pulled it away. I replaced it with the brand new one from the choke rebuild/conversion kit so that seal should be all good. Edited March 30, 2017 by DV8 (see edit history) Link to comment Share on other sites More sharing options...
alini Posted January 21, 2017 Share Posted January 21, 2017 You can remove the choke and pass a thin wire though the passage to make sure its not clogged. As long as you have action in the choke and it opens as the car warms up, I wouldnt sweat the vacuum part, you have heat getting there and thats all you really want Link to comment Share on other sites More sharing options...
carbking Posted January 21, 2017 Share Posted January 21, 2017 The piston does not close off the vacuum. There is not a lot of vacuum at the choke housing inlet, but there should be a little. You may not feel it with your fingers, but if you put a small piece of tissue paper over the inlet, the paper should be held there by the vacuum. Some vacuum is necessary to assure that sufficient heat is pulled into the choke to keep it open. Jon. 1 Link to comment Share on other sites More sharing options...
JZRIV Posted January 21, 2017 Share Posted January 21, 2017 Make sure the gasket on the round cover is in place and sealing also. For whatever reason mine would not seal so I doubled the gasket. When I was troubleshooting and put a vacuum gauge on the inlet end of tube by air horn, I noticed when I pushed in on the round cover I had great vacuum. Once this was solved I was able to get the correct "pull-off" action and choke function. 1 Link to comment Share on other sites More sharing options...
DV8 Posted January 25, 2017 Share Posted January 25, 2017 And one more query so I can get this setup properly: The stove pipe connects to the exhaust manifold at the opening that has the nipple and the clean air supply goes into the end that is about a 1/4" hole or other way around? I still have yet to find a photo of this setup correctly anywhere on the internet so if anyone has one it would help me out a lot. Link to comment Share on other sites More sharing options...
carbking Posted January 25, 2017 Share Posted January 25, 2017 On 1/21/2017 at 10:00 AM, JZRIV said: Make sure the gasket on the round cover is in place and sealing also. For whatever reason mine would not seal so I doubled the gasket. When I was troubleshooting and put a vacuum gauge on the inlet end of tube by air horn, I noticed when I pushed in on the round cover I had great vacuum. Once this was solved I was able to get the correct "pull-off" action and choke function. This occurs because of warpage of the metal choke housing from the cover retaining screws being overtightened. If the carb is disassembled for rebuilding, the housing should be straightened using mild heat, a jig, and pressure. A close examination should reveal that the bosses housing the threads for the retaining screws are no longer plumb, and have created a "high center" between screws. A double gasket is only a temporary fix, which will cause additional warpage. Jon. Link to comment Share on other sites More sharing options...
RivNut Posted January 26, 2017 Share Posted January 26, 2017 1 hour ago, DV8 said: And one more query so I can get this setup properly: The stove pipe connects to the exhaust manifold at the opening that has the nipple and the clean air supply goes into the end that is about a 1/4" hole or other way around? I still have yet to find a photo of this setup correctly anywhere on the internet so if anyone has one it would help me out a lot. The fresh air supply nipple is on the air horn of the carb; toward the back on the passenger's side of the carb. It connects to the bottom of the hot air tube that runs through the exhaust manifold; it's part metal pipe and part hose. The hot air supply is the metal pipe that wrapped in the mesh. It runs from the top of the tube in the exhaust manifold directly to the choke on the carb. This picture was copied from a post by Super48 from a thread here on the forum back in Aug. of '16 The following picture is representative of the many castings of passenger side exhaust manifolds. You can see the upper and lower ends of the choke tube sticking out of the manifold; the tube runs straight through the port from the rear cylinder. Clamps would hold the metal choke pipes in place but they're not screwed into the tube. The ends of the pipes are tapered and they slip fit into the choke tube. Hope this helps Ed Link to comment Share on other sites More sharing options...
alini Posted January 26, 2017 Share Posted January 26, 2017 Do these help?? 1 Link to comment Share on other sites More sharing options...
DV8 Posted January 26, 2017 Share Posted January 26, 2017 (edited) Yes, Chris. That first photo is exactly what I needed. Thanks! Edited January 26, 2017 by DV8 (see edit history) Link to comment Share on other sites More sharing options...
RivNut Posted January 26, 2017 Share Posted January 26, 2017 8 hours ago, DV8 said: Yes, Steve. That first photo is exactly what I needed. Thanks! You do realize that the picture you reference does not show the fresh air tube running from the car to the bottom of the exhaust manifold. Link to comment Share on other sites More sharing options...
DV8 Posted January 26, 2017 Share Posted January 26, 2017 (edited) Yeah it does. It's a little blue-ish in the photo. I see it. Pretty sure Chris sees it. AmIRight?! Edited January 26, 2017 by DV8 (see edit history) Link to comment Share on other sites More sharing options...
RivNut Posted January 26, 2017 Share Posted January 26, 2017 (edited) 1 hour ago, DV8 said: Yeah it does. It's a little blue-ish in the photo. I see it. Pretty sure Steve sees it. AmIRight?! Nope, that looks like a spark plug wire. The top picture in post #34 shows a black rubber hose connected to a steel tube, that it clamped to the valve cover hold down bolt. That is the fresh air tube. In the second picture in post #35, if you look closely, you'll see a rubber plug on the fresh air nipple on the carb's air horn. Edited January 26, 2017 by RivNut (see edit history) Link to comment Share on other sites More sharing options...
alini Posted January 26, 2017 Share Posted January 26, 2017 There two tubes that go to the exhaust manifold. The fresh air tube ed is referring to connects from the passenger side of the top of the carb and runs almost straight down to the front of the crossover tube. That tube uses filters fresh air from the air cleaner down to the cross over where it is heated by exhaust gasses and then back up from the rear of the carb to the choke housing as routed in the pics I posted. Two different tunes. Many guys don't run the fresh air tube and in my opinion it's not needed because you will have a slight vacuum draw there too which will offset the vacuum at the choke housing. If you have your stove pipe hooked up and the choke works it's up to you if you want to run the fresh air tube. I'm betting you will have to make one since it sounds like you don't have it installed already p.s. My name is Chris Link to comment Share on other sites More sharing options...
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