dual kadrons run rich on 1 and 3

[Gezz]

New to the forum, found it very helpful in the past, but seems I have an issue not previously addressed. My 69 douible cab has a 1914 engine with dual Kadron 40's. Running rich on 1 and 3. Adjusted valves, compression OK, and burn on 2 and 4 is perfect. Idles smooth and runs strong but terrible mileage. Any suggestions appreciated. thanks

[aeromech]

How do you know 1 and 3 are rich? By reading the spark plugs? I’m not a fan of Kadrons but did have luck with a pair last summer. So, Kadrons are one carb for two cylinders unlike say Weber 40 IDF’s which are actually two carbs in one. In other words each cylinder is fed by its own carb even though most people don’t think of it that way. I read somewhere that Kadrons don’t atomize the fuel well for each cylinder at idle and this causes 1 and 3 to appear rich but at power they do. Take this for what it’s worth (not much) but that’s what I remember. You might contact Kaddie Shack and ask them or maybe they have a tech article on their website
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[Gezz]

Plugs dead black on 1&3. Tan on 3&4. I am doing mostly local driving. Maybe need to run it down hwy.

[mikedjames]

The VW firing order means that the cylinders each side fire unevely - there is a big gap while the other side fires, then the two cylinders fire in rapid succession.
Depending on the carburettor design, it may be better or worse at metering the fuel with uneven air flow.
You have Kadrons, which are a well-marketed product in the USA and mostly ignored elsewhere, with a reputation for being more tempramental than some other solutions.
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[aeromech]

They say to read the plugs correctly you should do a high speed run, shut off the engine, and coast to stop before reading them
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Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
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Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[aeromech]

I think a better solution would be to use a laser thermometer pointed at each exhaust port
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Gezz]

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69 Double Cab
73 Thing
2015 New Beetle Convertible

[aeromech]

Nice
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[richparker]

I’ve run Kaddies a couple of times, both times I changed them out for idf40s.

If you’re getting poor mileage you most likely need to re-Jet them.

https://www.thesamba.com/vw/forum/search.php?searc...=titleonly
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[Gezz]

I spoke with Jeff at Kaddie Shack yesterday, great guy and very helpful. He agrees that my plug analysis is flawed as I do mostly local driving less than 45 mph and stopped in traffic. (Price to pay for living on the beach). I will try a slightly smaller idle jet, I am currently running 145 main and 55 idle with a 30 Venturi.
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73 Thing
2015 New Beetle Convertible

[Gezz]

and thanks for the replies.
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Beachside Mechanic
69 Double Cab
73 Thing
2015 New Beetle Convertible

[Bulli Klinik]

With your style of driving, you might consider backing off the accelerator pump as well. Constantly on and off the gas is giving a healthy dose of fuel every time you push the pedal. Adjust it so you have just enough so that it doesn't stumble and transitions smoothly.
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[aeromech]

Here’s a video from Kaddie Shack



Link

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Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Gezz]

thanks for the link, they do not post recommendations on jetting, only the process for changing the venturi and jets. I spoke with Jeff and understand that there can be many combinations. Not ready to send my carbs off to him, still tweaking them myself. I am in LA this week but when I return will go back over everything, compression, timing, and reconfirm all is on point and then reset the carbs.
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Beachside Mechanic
69 Double Cab
73 Thing
2015 New Beetle Convertible