Hans3 Posted February 23, 2023 Share Posted February 23, 2023 Having trouble sourcing a fitting to connect the flexible rubber supply hose to the fuel pump (1947). I'm not sure what an original (male/male?) fitting looks like but the threads should be 1/2-20. The question is whether one end is supposed to be an AN fitting or are both straight-cut threads? If it's an AN then it corresponds to a 5AN size, which is proving tough to find. Hose pic attached for reference; thank you much. Link to comment Share on other sites More sharing options...
FireballV8 Posted February 24, 2023 Share Posted February 24, 2023 Usually the end you are showing goes to the flare fitting on the steel line, then the other end of the hose with the male thread would go to the fuel pump or use a 45 or 90 degree angle fitting at the fuel pump. What does the other end of the hose look like? 1 Link to comment Share on other sites More sharing options...
Bloo Posted February 24, 2023 Share Posted February 24, 2023 This^^ Also, you'll need to show us the inside of the fitting. It's not AN. It's either threaded sleeve or double flare. A look inside that fitting will sort out which. My guess is double flare. Link to comment Share on other sites More sharing options...
Hans3 Posted February 25, 2023 Author Share Posted February 25, 2023 It's a pump supply hose obtained from CARS. I believe the left fitting connects to the supply line flare. My fuel pump is missing the OEM threaded inlet fitting, so I'm not sure what it looks like. 1 Link to comment Share on other sites More sharing options...
Frank DuVal Posted March 2, 2023 Share Posted March 2, 2023 It looks like the left fitting is inverted flare and the right one is normal 45° flare. But, not sure. Take another picture at a lightly different angle? The fuel pump is probably a 1/8" NPT. Take a picture of that hole too if possible. 1 1 Link to comment Share on other sites More sharing options...
Bloo Posted March 2, 2023 Share Posted March 2, 2023 (edited) Nothing about this looks normal to me. I must be missing something. Is there a double flare fitting on the end of the fuel line coming from the tank? Or maybe a threaded sleeve fitting? The left looks like it connects to a double flare. The right looks like threaded sleeve, but that doesn't make any sense unless there is another piece of steel tubing before you get to the fuel pump. I think some Buicks may have had something like that, where they crossed from the frame with the rubber line further back, then went back to steel tubing again to go forward to the fuel pump. You wouldn't normally use a female threaded sleeve fitting (like I believe I see on the right) to go to a brass fitting to connect to a fuel pump. I don't think the brass fitting to do that exists. Maybe a plumbing fitting for single flare copper tubing might do it, but I am skeptical. I think the shape is different, and I have never encountered anything like that on a steel and rubber fuel line setup. You might be able to horsehash it with a real short piece of steel tubing, using either one double flare and one threaded sleeve nut, or just two threaded sleeve nuts, but I have a hard time believing Buick or anyone else did that at the factory. Pontiac did the opposite, with male threaded sleeve hose end connecting to the fuel pump, but in that case the hose end fitting just resembles a piece of straight tubing that you can put a threaded sleeve nut on. It doesn't look anything like the end of your hose. In that setup, a female threaded sleeve to pipe thread adapter screws into the pump. Like @Frank DuVal, I'd like to see another angle. I'd also like to see the end of the fuel line and also the spot where this all fits in the car. For reference, a double flare: And a threaded sleeve: Edited March 2, 2023 by Bloo (see edit history) 1 Link to comment Share on other sites More sharing options...
Hans3 Posted March 2, 2023 Author Share Posted March 2, 2023 Thanks for the replies. Attached is a photo from a BAT auction 1946 car with the setup I believe my '47 is supposed to have. My new rubber hose is straight from Cars and applicable to multiple years'. I suspect, but will need to verify, that the tubing from this hose to the pump is 5/16 imperial brake tubing. This photo obscures the fitting connection at the pump, unfortunately. Note the fuel supply tube retaining clip on the crankcase blowby tube. Link to comment Share on other sites More sharing options...
Bloo Posted March 2, 2023 Share Posted March 2, 2023 (edited) That makes more sense. What does the end of the line (on the chassis) that you are going to hook your hose to look like? Is it double flared? Straight? I can't see enough in the pics to tell for sure, but it looks like one end of the hose you have is for a double flare and the other end is for a threaded sleeve. Yes, it is all 5/16" American-type steel brake tubing aka "Bundyflex". I suspect CuNiFer could work, but have not personally tried it with threaded sleeves. The plastic coated brake line that parts stores seem to favor sounds like a bad idea to me, but I haven't tried that with threaded sleeves either. At some point, you will need to get a picture of what happens at the front. You connect from the piece of steel bundyflex tubing to pipe thread at that end. It could have been a threaded sleeve on the tubing or a double flare, I don't know which. I would guess double flare. Either will work. The pipe thread on the fuel pump will be female tapered pipe thread, probably 1/8" NPT. Brass fittings exist to go from either type of tubing end to the pipe thread of the fuel pump. The fittings for double flare are typically easier to get. If you need right angle for threaded sleeve, the 5/16" fitting is discontinued, and is a swap-meet-only sort of item. The straight fitting for threaded sleeve, and also the threaded sleeve nuts, are available at Blackhawk Supply. The equivalent double flare right angle and straight fittings (to connect double flare to NPT) are relatively common auto parts store items. Edited March 2, 2023 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
Frank DuVal Posted March 3, 2023 Share Posted March 3, 2023 Bloo says "double flare" and I say inverted flare. Same thing, different parts of the country? The under car picture shows that rubber hose going between two inverted flare fittings (i.e. typical steel line/ Bundy Flex fittings) or as you said, Imperial Brake Tubing (never heard that before, but there it is on Google!). The hose in that picture is made from rubber fuel line and two "push on hose inverted flare fittings". You can tell by the yellow plastic rings. https://www.google.com/search?q=push+on+hose++inverted+flare+fittings&rlz=1C1VDKB_enUS969US969&ei=ZYsBZJrQFamp5NoPpt222AY&ved=0ahUKEwjalo2Kib_9AhWpFFkFHaauDWsQ4dUDCBA&uact=5&oq=push+on+hose++inverted+flare+fittings&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQA0oECEEYAFAAWABgAGgAcAB4AIABAIgBAJIBAJgBAKABAQ&sclient=gws-wiz-serp So that hose is not a reproduced item, but a made up item to fit. Your hose was supplied as a reproduced item. Your picture does not look like it is inverted flare on both ends. But, might just be the picture. What do the ends of the steel lines in the car now look like? 2 Link to comment Share on other sites More sharing options...
Bloo Posted March 3, 2023 Share Posted March 3, 2023 (edited) 2 hours ago, Frank DuVal said: Bloo says "double flare" and I say inverted flare. Same thing, different parts of the country? Maybe. I've heard "inverted flare" a lot too, but double flare seems to be default around here. Yes, same thing. The "Imperial" terminology has become common because of the Internet I think, mostly when contrasting inch dimension parts against metric. They probably say that in the UK and maybe other countries that were more closely tied to the UK than we were, but now it has spread worldwide. A Swedish friend of mine has also used "Imperial" to refer to inch-based things for as long as I can remember. I tend to shun "Imperial" because even though it isn't technically wrong, it implies that it is an alternative system to metric when in fact it is just everything that isn't metric, and that includes a lot of different systems. I usually say "SAE" when talking about American stuff. Unfortunately that is technically wrong part of the time, but at least it leaves no doubt you are talking about American standards based on inches, US gallons, etc. I don't really know a better way. Edited March 3, 2023 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
Hans3 Posted March 3, 2023 Author Share Posted March 3, 2023 Always liked the sound of imperial. Anyway attached are photos of my supply tube end-fitting that connects to the rubber hose and the fuel pump inlet. Supply line does not appear to have a double flare. Based on above comments regarding the fuel pump inlet threads, I presume the fuel pump will need a 1/4 (?) male NPT to 1/2-20 female adapter? 1 Link to comment Share on other sites More sharing options...
Frank DuVal Posted March 6, 2023 Share Posted March 6, 2023 (edited) I thought you meant fittings made by the Eastman Imperial corporation! Never occurred to me you meant Imperial as in SAE NPT Metric. Edited March 6, 2023 by Frank DuVal (see edit history) Link to comment Share on other sites More sharing options...
Frank DuVal Posted March 6, 2023 Share Posted March 6, 2023 (edited) On 3/3/2023 at 3:11 PM, Hans3 said: Supply line does not appear to have a double flare. It sure does! If it was a single flare the sharp edge from the end of the steel tube would be at the end of the tube. Your sharp edge is up inside the tube. This is because it took two operations to make the flare. Single flare is just put 45 degree cone into end of tube. Inverted flare is first make a bubble in the end of the tube (like the bubble flare on newer cars) then put 45 degree cone into the bubble and bend the sharp edge back into the tube. Fuel pump might be 1/8”NPT but could be 1/4”. Remember pipe size (NPT) is the size of the hole through the pipe not OD! Steel tubing is sized on OD. Edited March 6, 2023 by Frank DuVal (see edit history) 2 1 Link to comment Share on other sites More sharing options...
Bloo Posted March 6, 2023 Share Posted March 6, 2023 (edited) On 3/3/2023 at 12:11 PM, Hans3 said: Always liked the sound of imperial. Anyway attached are photos of my supply tube end-fitting that connects to the rubber hose and the fuel pump inlet. Supply line does not appear to have a double flare. Based on above comments regarding the fuel pump inlet threads, I presume the fuel pump will need a 1/4 (?) male NPT to 1/2-20 female adapter? That's a double flare. What model is this? Is that the line coming from the chassis? Assuming it is, connect the double flare end of the rubber hose to that. Use a 5/16" threaded sleeve to connect the other end of the hose to a piece of 5/16 brake tubing. Brake tubing usually comes double flared at both ends, with one nut that looks like the one on old cars, and one that is much longer. The long one fits all the same stuff, it just looks wrong. You don't need it anyway, you need at the most one correct looking nut (maybe none) and the piece of brake tubing will have one. You'll need a tubing bender of course. The only pics I could find online that show the front end of the line on a car that has the line attached to the draft tube were of this 47 Roadmaster. It looks pretty messed with and wrong at the hose end, but you get the idea. So if this is correct it uses a straight fitting at the fuel pump. I would have guessed a 90 degree fitting but apparently not. At the fuel pump end you need to get from the 5/16" brake tubing to 1/8" NPT pipe thread. You have 2 choices. Option 1 is the easiest. Use your one good looking nut and one premade double flare end from your piece of brake tubing. Use a 5/16" double flare (AKA inverted flare) female to 1/8" male NPT brass fitting on the fuel pump. Thread sealer on the pipe threads might be a good idea, but isn't strictly necessary. Don't use tape. The double flare end needs nothing. Option 2 is to cut off the front end of the brake tubing also, and use a second threaded sleeve. In that case you would need a 5/16 female threaded sleeve to 1/8" NPT brass fitting. Blackhawk supply has that, as well as the threaded sleeve nuts. You'll need at least one threaded sleeve nut to connect to second end of the rubber hose. https://blackhawksupply.com/collections/plumbing-brass-fittings-double-compression They also should have the double flare to pipe fitting you need at the fuel pump if you go with option 1, however that is a super common parts store item, and I am fairly sure you can get that locally. I don't know which option Buick used. I suspect the option 1 (double flare). Either will work fine. Edited March 6, 2023 by Bloo (see edit history) 1 Link to comment Share on other sites More sharing options...
Hans3 Posted March 7, 2023 Author Share Posted March 7, 2023 Thanks for the informative replies; I stand corrected on the flare type and NPT fitting size. This is for a '47 Super. Only thing I'm not clear on is why a threaded sleeve is needed to connect the 5/16 steel brake line (that goes to pump via 1/8 NPT) to the new flexible rubber hose. Don't the brake line and flex hose fitting both have 1/2-20 thread? Also out of curiosity why is (oil resistant) pipe tape a no-no for the pump connection? Will fuel break it down? 1 Link to comment Share on other sites More sharing options...
EmTee Posted March 7, 2023 Share Posted March 7, 2023 1 hour ago, Hans3 said: Also out of curiosity why is (oil resistant) pipe tape a no-no for the pump connection? Will fuel break it down? The issue with the tape is that pieces ("threads") could break free as the fitting is tightened. Once inside the fuel line, it could potentially cause trouble. If there's a filter between the pump and carburetor then maybe nothing bad happens, otherwise it could foul the needle valve and cause the bowl to flood with fuel. 1 Link to comment Share on other sites More sharing options...
Bloo Posted March 7, 2023 Share Posted March 7, 2023 8 hours ago, Hans3 said: Only thing I'm not clear on is why a threaded sleeve is needed to connect the 5/16 steel brake line (that goes to pump via 1/8 NPT) to the new flexible rubber hose. Because the hose appears to have a threaded sleeve connection on one side. If that's not true, and there is really a flare seat in there, then you wouldn't. Or you could get a different hose. Or you could make your own hose with a couple of double flare 5/16" hose barbs. If you used 30R9 hose and fuel injection clamps, it would probably be the best solution from a technical viewpoint, but would be obviously wrong if you plan to do judged shows. 8 hours ago, Hans3 said: Also out of curiosity why is (oil resistant) pipe tape a no-no for the pump connection? Will fuel break it down? Because bits of it break off and cause all sorts of havoc. The most common place for it to get stuck is in the float valve. It has caused a lot of car fires over the years. It's really a bad idea anywhere on a car, not just the gas line. Technically you don't need sealer on tapered pipe thread (NPT) anyway, and on the other fittings the threads don't do the sealing. If thread sealer is wanted, plenty of other thread sealers do exist that aren't in tape form. Link to comment Share on other sites More sharing options...
Hans3 Posted March 8, 2023 Author Share Posted March 8, 2023 To work properly don't these (typically brass) threaded sleeves work only with tubing that's equally soft? Or can the brass still crush mild steel? Link to comment Share on other sites More sharing options...
Bloo Posted March 8, 2023 Share Posted March 8, 2023 (edited) I don't think the manufacturer currently recommends using them with steel. They are all over old cars used with steel, and it works fine. The first time it is assembled, you might have to make it fairly tight. Properly installed, the sleeve bites into the tubing and becomes part of it. You should be able to take the tube and nut loose from the female fitting as many times as you want, but the nut remains attached to the tube. If there's any doubt, take it apart and look. Steel brake tubing ("Bundyflex") has layers of copper rolled into the steel during manufacture to facilitate bending. It is a bit more malleable than pure steel would be. Maybe that's a factor. This replacement steel line was made in the mid 2010s usingbrake tubing from NAPA and threaded sleeves from Blackhawk. I did take it back off after the initial crush to inspect. Edited March 8, 2023 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
EmTee Posted March 8, 2023 Share Posted March 8, 2023 (edited) Just a thought... If the tubing still wants to pull out of the threaded sleeve after tightening the fitting, I might try clamping the tubing in my double flaring tool with the threaded sleeve on top of the bar and about 1/16" of tubing sticking out of the tapered end of the sleeve. Then use the flare arbor (2nd step of the double-flare process) to just ever so slightly spread the end of the tube so it can't pull out and give the threaded sleeve something to bite into. Edited March 9, 2023 by EmTee typo (see edit history) 1 Link to comment Share on other sites More sharing options...
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