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Wed Apr 30, 2025 9:34 am

Kadron carbs have a place in the V'Dub world but its an area with scant technical info and can be frustrating. I've been dealing with an issue that's spanned across several years (off and on) since my bus sat for a long duration without being ran. I thought I might post this to the Kadron users out there just in case you are experiencing this as well.
Carbs in question: H40/44 EIS on a type 4 bus engine 1.8L (later built out to 2L with long duration cam).
I installed these carbs on the original engine which had unknown mileage because the original Solex carbs were not performing their best and I wanted some added performance without breaking the bank on Webers. After installing the carbs I could not get them dialed no matter what I tried. First I went through the typical routine we all know about with Kadrons, setting idle mixture, setting idle RPM, making sure timing was right, adjusting valves.... you know the story. The routine was spotty at best, often changing from one moment to the next without any reason, making me second guess my work, then back to square one and go at it again.... After countless attempts to get his right I finally bit the bullet and took the bus to a local shop to let them have a go.. The shop tried multiple things like swapping jets, drilling on the top of my idle correction jet for some reason, changing a float, messing with accel pump setting and so on.. Nothing they did seemed to solve the issue. What was the issue you ask? A hesitation at low to mid throttle at almost any speed but most noticeable at 30-50MPH. This hesitation felt almost exactly like a engine about to run out of fuel but a bit less abrupt so it was just enough to notice and be annoyed by. In addition to this constant hesitation, there was popping from one carb and terrible fuel mileage. I finally decided that maybe my issue wasn't carb related but engine related, so I spent filthy sum of money having a 2liter rebuild done with a nice long duration 380/285 cam. The engine has a compression ratio of 7.6:1 dynamic. After the rebuild the mechanic tuned the Kadrons as best he could but mentioned that he was a Weber guy and didnt have much knowledge on the Kadrons. In short this meant the engine was "running" but he suggested I buy new carbs and a new exhaust system to resolve the lack of tuneability. The hesitation was still there even with the newly rebuilt engine. I went back at it again using the same tricks trying desperately to find the culprit, rejetted the carbs for the new engine, put in new 32mm venturis, checked float level, jets, vac leaks, throttle linkage, bushings, on and on..... One thing that was obvious this whole time was the left carb had little to no reaction from the idle mixture screw setting. As most of you know the Kadrons use a balance tube so they tend to feed off one another on the settings, but the idle mixture screw should still cause a RPM change when adjusting it. I broke the carbs down again, cleaned everything and finally found the culprit. After taking out the main jet and turning the carb upside down a little galley port plug (brass) fell out of the carb bowel. At first I had no clue where it came from and did not even think about the fact that it could have come from the main jet galley, but after exhaustive searching online I finally discovered that the idle correction jet on a Kadron has the emulsion tube connected to the base of the jet, and on the bottom of the emulsion tube there is a small brass press in plug.. This plug fell out of the emulsion tube and was rattling around in my main jet galley this entire time. So after much hair pulling and belly aches, I think I found the issue. Of course Kadron correction jets are not made to be swapped and this is an issue all on its own, but with care and attention one can still get them out to replace with a new one. There are multiple posts regarding removal of the emulsion tube and I will leave most the details out because of that. Here is a quick and dirty rundown on replacing the jet. Method one: Use a drywall screw and thread it into the correction jet every so carefully and as straight as possible making sure not to score the carb body itself. Once the screw has been twisted in about half way (1" long screw) you can use a slide hammer or some other method such as a nail puller to pull the pressed in jet form its seat. Its a light press fit so shouldn't be too much pressure to get it moving. The new jet can be installed by light tapping into the seat with a softer material such as a plastic mallet head or maybe a copper punch. Method two: Using a hair dryer or other source of heat, apply the heat to the jet top until you get it at least 180-200deg F. You can read the localized heat with a heat temp gun or just blister your finger tip by touching the jet top! Hey some things are worth fighting for right? Once its nice and hot you can get the jet out with a bit less pressure. Hope this helps you Kadron fans out there.

Wed Apr 30, 2025 11:27 am

Ever heard of paragraphs? I'm not going to attempt to read that ^.

Wed Apr 30, 2025 11:49 am

Easier for ya now?
crowesnest wrote: Kadron carbs have a place in the V'Dub world but its an area with scant technical info and can be frustrating. I've been dealing with an issue that's spanned across several years (off and on) since my bus sat for a long duration without being ran. I thought I might post this to the Kadron users out there just in case you are experiencing this as well.

Carbs in question: H40/44 EIS on a type 4 bus engine 1.8L (later built out to 2L with long duration cam).
I installed these carbs on the original engine which had unknown mileage because the original Solex carbs were not performing their best and I wanted some added performance without breaking the bank on Webers. After installing the carbs I could not get them dialed no matter what I tried. First I went through the typical routine we all know about with Kadrons, setting idle mixture, setting idle RPM, making sure timing was right, adjusting valves.... you know the story. The routine was spotty at best, often changing from one moment to the next without any reason, making me second guess my work, then back to square one and go at it again.... After countless attempts to get his right I finally bit the bullet and took the bus to a local shop to let them have a go.. The shop tried multiple things like swapping jets, drilling on the top of my idle correction jet for some reason, changing a float, messing with accel pump setting and so on.. Nothing they did seemed to solve the issue. What was the issue you ask? A hesitation at low to mid throttle at almost any speed but most noticeable at 30-50MPH. This hesitation felt almost exactly like a engine about to run out of fuel but a bit less abrupt so it was just enough to notice and be annoyed by. In addition to this constant hesitation, there was popping from one carb and terrible fuel mileage.

I finally decided that maybe my issue wasn't carb related but engine related, so I spent filthy sum of money having a 2liter rebuild done with a nice long duration 380/285 cam. The engine has a compression ratio of 7.6:1 dynamic. After the rebuild the mechanic tuned the Kadrons as best he could but mentioned that he was a Weber guy and didnt have much knowledge on the Kadrons. In short this meant the engine was "running" but he suggested I buy new carbs and a new exhaust system to resolve the lack of tuneability. The hesitation was still there even with the newly rebuilt engine. I went back at it again using the same tricks trying desperately to find the culprit, rejetted the carbs for the new engine, put in new 32mm venturis, checked float level, jets, vac leaks, throttle linkage, bushings, on and on..... One thing that was obvious this whole time was the left carb had little to no reaction from the idle mixture screw setting. As most of you know the Kadrons use a balance tube so they tend to feed off one another on the settings, but the idle mixture screw should still cause a RPM change when adjusting it. I broke the carbs down again, cleaned everything and finally found the culprit. After taking out the main jet and turning the carb upside down a little galley port plug (brass) fell out of the carb bowel. At first I had no clue where it came from and did not even think about the fact that it could have come from the main jet galley, but after exhaustive searching online I finally discovered that the idle correction jet on a Kadron has the emulsion tube connected to the base of the jet, and on the bottom of the emulsion tube there is a small brass press in plug.. This plug fell out of the emulsion tube and was rattling around in my main jet galley this entire time. So after much hair pulling and belly aches, I think I found the issue. Of course Kadron correction jets are not made to be swapped and this is an issue all on its own, but with care and attention one can still get them out to replace with a new one. There are multiple posts regarding removal of the emulsion tube and I will leave most the details out because of that. Here is a quick and dirty rundown on replacing the jet.

Method one: Use a drywall screw and thread it into the correction jet every so carefully and as straight as possible making sure not to score the carb body itself. Once the screw has been twisted in about half way (1" long screw) you can use a slide hammer or some other method such as a nail puller to pull the pressed in jet form its seat. Its a light press fit so shouldn't be too much pressure to get it moving. The new jet can be installed by light tapping into the seat with a softer material such as a plastic mallet head or maybe a copper punch.
Method two: Using a hair dryer or other source of heat, apply the heat to the jet top until you get it at least 180-200deg F. You can read the localized heat with a heat temp gun or just blister your finger tip by touching the jet top! Hey some things are worth fighting for right? Once its nice and hot you can get the jet out with a bit less pressure. Hope this helps you Kadron fans out there.
That shop should have recignized that there was an issue with that carb and suggested to at least replacing it. There can be issies with all carbs no matter the brand. The "get some Webers" comment is most often an indication that the guy with the wrench don´t know what he´s doing, and can probably not tune a set of Webers properly either. That said, Webers can be quite time consuming to get to run right. not my favourite carb, but its more or less what we get these days.
I kinda like Kadron engines, - as long as people don´t overcam them. Here less is often better