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andk5591
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 Posted: Sat Feb 06, 2010 4:16 pm Post subject: Kad prob - fuel from accel pump at 3/4 to full throttle |
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Dynoing the engine and we have gone through the jetting, but have discovered a really odd thing. At steady full throttle, fuel is dumping in from the accelerator pump nozzles. We played with the pump linkage quite a bit and even went so far as to back the adjustment nut out completely and its makes no difference. On the chassis dyno with the car running pretty quick and it's floored, you can move the lever to any position and it doesn't stop it. When it occurs, the engine also kind of sputters, which one would almost expect.
We also went all through the accel pump linkage adjustment so its not dripping fuel at idle as well. Also went through AJs procedure.
We pulled the accel pump nozzle and it looks like there is a check ball in there. Both carbs do it. Can you clue me in to why this is happening?
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D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
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Last edited by andk5591 on Mon Feb 08, 2010 4:52 am; edited 1 time in total |
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Max Welton
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andk5591
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| Posted: Sun Feb 07, 2010 8:04 am Post subject: |
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A little over 2 lbs. I am having one hell of a time figuring out how the fuel is getting sucked through the pump circuit. We went all through AJs accel pump procedure, then played with a wide range of accle pump adjustments (nut real loose, nut tight with spacer nut). And once again - does it on both carbs....
Thinking this is check ball related, but can't even visualize how it works in this circuit. I know where it is, but what exactly is it supposed to do - the only thing that I can see is that it would prevent the fuel backflowing into the accel pump......
Unrelated question (kind of) As I was just double double (and triple) checking everything yesterday, with the big assed vent, I don't see how you could ever over pressure the fuel bowl in a Kad. I mean obviously too much pressure could overpower the needle valve and your level would be too high and fuel would leak down into the throat.
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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Max Welton
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Racebug57
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| Posted: Sun Feb 07, 2010 11:20 am Post subject: |
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Would it be possible for the accelerator pump diaphragm to be the wrong size?
I have seen some solex diaphragms that have the same bolt pattern with a longer or shorter throw. |
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andk5591
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| Posted: Mon Feb 08, 2010 5:08 am Post subject: |
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Thinking about this some more. Once you pump the fuel, that should be it. The only thing that I can think of is that the nozzles are down in the carb throat too far and the air flow is drawing fuel. Anybody konw what that distance from the top of the airhorn to the nozzel exit?
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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volksterii
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| Posted: Mon Feb 08, 2010 7:03 am Post subject: |
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Kadrons do want no more than 1.5lbs of fuel pressure. I would start by reducing that pressure.
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[email protected]
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| Posted: Mon Feb 08, 2010 7:23 am Post subject: |
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I don't know Kadrons that well, but some carbs open the pump circuit as a "WOT Enrichment" device. Going WOT pushes the checkball open and allows vacuum in the carb throat to pull fuel to prevent anything resembling lean.
On carbs with this feature, it's all the more reason to not be too rich on the mains, because at WOT you'll be even richer.
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57baja
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| Posted: Mon Feb 08, 2010 8:11 pm Post subject: |
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Good point John. That's an interesting thought. Hmmm.
Here are a couple of thoughts, based upon my general understanding of Kadrons, and a lot of years of tinkering with them, rebuilding them, re-bushing them, and fixing other people's cars that were set up wrong. That's not to say I'm anywhere near the expert that AJ is, but I do have a fair understanding of what's going on. PLEASE correct me if I'm wrong on anything:
First of all, starting from the bottom where the fuel is sucked into the pump circuit, I drew arrows to show the path of the fuel. The ball (check valve) is in the tube where the arrow points straight up. It's job is to prevent air (and fuel) from being sucked back into the pump chamber when pump diaphragm is on the "rebound" cycle. It works with gravity, and with the vacuum that is created by the pump diaphragm.
Think for a minute about the fuel level in the bowl. It is somewhere near the top in a normally running carb. Let's say that the float is not floating properly (perhaps the float and dogbone are reversed, the float is sunk, the float is bent, etc...), and the fuel level is higher than it should be. The fuel level could rise to the point where it is close to the top of the bowl, but not spilling out the vent yet, or if it was, perhaps it was not discernible due to the small amount. Now, with the added vacuum created by the air funneling down the venturi, the fuel could possibly get through the whole circuit and creating a p-trap, or a syphon, sucking more fuel as it got started.
The check valve ball, as I understand it, does not prevent fuel from going up, it prevents air (fuel)from going down, although its very weight may somehow regulate the amount of fuel that goes up.
Bear with me, I'm thinking out loud...
If the fuel pressure was too high, contributing to the fuel level being too high, that could cause all of this. I would add some extra gaskets under your fuel pump before going any further to eliminate that as a possibility. I personally think that might solve it. We KNOW what the fuel pressure should be, so why not start there and get that behind us as a possibility?
You have two separate carburetors that are doing the same thing, right? The only thing that both carbs share is fuel supply. I would start there. If one carb was doing it, I'd say you may have a float problem, or possibly another issue. The chances of BOTH of the carbs sharing the same problem is highly unlikely, though, unless they were incorrectly rebuilt by the same guy.
Whatever it ends up being, please post it, as I'm always quite curious about Kadron problems. They are a pretty simple carb, an for simple guys like me they usually work pretty damn good!
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57baja
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[email protected]
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| Posted: Mon Feb 08, 2010 8:32 pm Post subject: |
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the carbs that do it are set up simply. The arm of the accel pump diaphragm pushes in the checkball at WOT, opening up the circuit to vacuum.
Seeing that picture it is NOT setup for WOT enrichment thru the pump circuit.
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andk5591
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| Posted: Tue Feb 09, 2010 4:36 am Post subject: |
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This is great - thanks all - we have been getting a little(?) bit of snow here and I wont be back at the shop till Thursday. Will double check my fuel pressure and probably drop it a bit and see what happens. Will let you know what we find.
BUT any chance of knowing the correct location and depth of the accel pump nozzle? One possibility that also has been suggested is if it's too low and too far in center it could draw fuel as well. Thanks
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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andk5591
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| Posted: Wed Feb 10, 2010 1:03 pm Post subject: |
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FIXED  I also got an email from AJ with a variety of solutions and tests. Verifed fuel pressure. AJ suggested "dead ending" the gauge amd I assumed that he meant to terminate a pressure gauge at the end of the line - I connected my gauge instead of one of the carbs and was measuring a little over 3lbs. I already brought a stack of fuel pump gaskets and made a couple thick ones (.030" and .060"). Put a 030 in and a heavier bottom gasket and it looked closer to 2lbs (real jumpy though). Put in my 060 instead of one of 030 and it looks like its under 2. BUT still did the same thing with the accel pump spraying fuel at 3/4 to full throttle. Bent one side up probably 1/2" and reangled it to spray where I think it's supposed to. Fixed!! Did the other side. Problem gone.
So - bottom line is that apparently the pressure in the carb throat was great enough to siphon fuel from the accel pump nozzle. Thank you all for your help - As they say on South Park, I learned something today.
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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trainman
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| Posted: Wed Feb 10, 2010 1:33 pm Post subject: Kad prob - fuel from accel pump at 3/4 to full throttle |
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I have been following this thread closely as I have dual Kads on a 1641 in a '69 bug. I have not seen anywhere where there is a float adjustment for these carbs. Dells are sensitive to fuel level and the float must be corrrectly set to maintain the fuel at the correct level in the bowl. But nothing about float level for Kads. Anyone care to comment on that?
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57baja
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| Posted: Wed Feb 10, 2010 7:20 pm Post subject: |
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| andk5591 wrote: |
FIXED I also got an email from AJ with a variety of solutions and tests. Verifed fuel pressure. AJ suggested "dead ending" the gauge amd I assumed that he meant to terminate a pressure gauge at the end of the line - I connected my gauge instead of one of the carbs and was measuring a little over 3lbs. I already brought a stack of fuel pump gaskets and made a couple thick ones (.030" and .060"). Put a 030 in and a heavier bottom gasket and it looked closer to 2lbs (real jumpy though). Put in my 060 instead of one of 030 and it looks like its under 2. BUT still did the same thing with the accel pump spraying fuel at 3/4 to full throttle. Bent one side up probably 1/2" and reangled it to spray where I think it's supposed to. Fixed!! Did the other side. Problem gone.
So - bottom line is that apparently the pressure in the carb throat was great enough to siphon fuel from the accel pump nozzle. Thank you all for your help - As they say on South Park, I learned something today. |
So... For future reference... How exactly did you bend it? Can you shoot a photo, and/or post a measurement?
Thanks dude.
As for float adjustment trainman, they don't really have one like Dells or Webs. There is one way you can "adjust" the float level, and that is by varying the size of the seals under the needle and seat. The good kits (non-Chinese ones) come with two different thicknesses for these seals. I use the thicker ones, and sometimes even double up on them, which brings the needle and seat down and closer to the float, making the float contact it earlier... thus the fuel level stays lower in the bowl. I suppose you could somehow accomplish that same thing by bending the float somehow.
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andk5591
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| Posted: Thu Feb 11, 2010 3:49 am Post subject: |
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I'll try to get a pic, but it was trial and error - the end of the nozzle is above where the throat tapers and its pretty close to the outside of the throat, but angled in toward the center. I think its hitting too close to the center of the butterfly, so I want to move it a little this evening. Trial and error.
To see if your car has the prob, you don't need a chassis dyno, just revving it and holding it fairly wide open, you can see if its doing it. Very curious what happens to my numbers. Was seeing about 70hp and just under 100 lbs at the wheels the other day, but it was waaaay rich at the top end .......I'm thinking that for a mild 1914, I'm not gonna see much more, but can now finish tuning.....
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D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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[email protected]
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| Posted: Thu Feb 11, 2010 8:17 am Post subject: |
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the squirt should hit the GAP between the throttle plate and the carb throat wall.
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andk5591
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| Posted: Thu Feb 11, 2010 8:45 am Post subject: |
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OK John, making sure I understand - it should sprayas close to the outer bore of the carb with out hitting anything - essentially, shoot straight down the carb. Correct?
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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[email protected]
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| Posted: Thu Feb 11, 2010 8:48 am Post subject: |
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well, you don't want it to hit metal, you want it to hit air and have that airflow carry it to the cylinders. That's the most effective way to provide the fuel to the cylinders during throttle opening.
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andk5591
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| Posted: Thu Feb 11, 2010 9:15 am Post subject: |
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Great - that's kind of what I was thinking. Thanks
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D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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