Tap into Kadron H40/44 for vacuum dizzy

Tom Bishop · Post by **Tom Bishop** » Thu Oct 12, 2006 6:55 pm

Hello

I am running a type 1 1600 fitted with a single Kadron H40/44 carb (bought as a kit from cip1) and 009 dizzy. I believe from Internet research the dizzy is the main cause for a flat spot @ 2000rpm. From what I have read you need the standard vacuum dizzy, but you need to tap into the carb for this.

Anybody know where to tap into this carb to fit the standard vacuum dizzy.

BTW.
I got da moor in with this flat spot and went out and bought a new 34pict carb. Fitted the original dizzy,inlet and carb. It idled and revved well, but on the road if you accelerated hard, it would pick up revs and then just about die. In the end I found that the needle and seat was wrong. not faulty but totally wrong for this carb. The fuel could only get 1cm deep in the bowl.

Cheers

Post by **Tony Z** » Thu Oct 12, 2006 8:15 pm

I have read about that too, even though my 009 doesnt have that spot....

What you want for the vaccuum is a spot anywhere after the butterflies. It is measuring the air pressure in the manifold, so a small spacer put under the carb with the hose fitting in it would do perfect.

Tom Bishop · Post by **Tom Bishop** » Fri Oct 13, 2006 8:10 am

I thought this was the place that I should tap in, some where in the manifold, but then read it should be between the bottom butterfly and the choke. They recon the vacuum here is exactly the opposite to the manifolds, and this is what the dizzy wants. (if you open your throttle the vacuum drops in the carb, but rises in the manifold and if the throttle closes the vacuum in the carb rises and the manifold drops.)

I assume this is the place to tap into (or do I have it wrong?) but where. I dont just want to drill a hole to find out I have gone into a duct.

Does anybody have diagrams of this carb? Can't find any on the net.

Cheers

Post by **Tony Z** » Fri Oct 13, 2006 8:37 am

vacuum drops in the carb, but rises in the manifold and if the throttle closes the vacuum in the carb rises and the manifold drops

does this statement make sense to you???
Look for a diagram of a weber IDF, no choke plates and the carb fitting in the mounting base....

I think what you are referring to is the pressure thru the venturi... the air speeds up thru the venturi, then expands and causes a low pressure over the venturi only, pulling fuel out of the main jet thru this press diff. At low speeds this speed is not available and neither is the press diff.

Here is proof...
when cruising at low power, high engine speed, you want the ignition advanced to roughly 46deg BTDC. Run the engine at idle with the vaccuum dizzy installed. Attach a timing light. Suck (with your mouth) on the dizzy vac tube and watch the revs advance.
At low power, high revs, the press in the manifold is near to vaccuum (same a sucking at idle) and this is when you want the timing to advance. At full throttle, the manifold pressure is near to atmospheric and this is when you dont want any vac adv - like holding the vac in the air.....

Post by **calooker** » Fri Oct 13, 2006 10:54 am

The single Kadron H40/44 carb setup is relatively new on the market, so you are not going to find much info on it. The twin Kadron H40/44 carb setup is more common and a lot more info is available on them. A lot has been written and said about the twin Kadron setup, and even the experts tend to disagree on the correct setup for the vac. pickup. Plumbing the carb for a vac. signal is a lot more complex than what was mentioned before, as it needs the signal coming in @ the correct revs and also dropping off at the right rev range to get the correct curve, so watch what you drill before you F-up the carb. http://www.lowbudget.com even have a specific dizzy for Kadrons, so it is complex. The 009 is well known for it's flat spot, even when run with a standard carb, did you try and run the single Kadron with the std. dizzy, it will work a little better than the 009, as it has both a mechanical and vac. advance you will just not have the initial advance of the ignition under load when you floor it, as the vac. signal can pick up the loading of the motor and advance accordingly, the 009 will only advance as the revs pickup. There is a dude in the US AJ Sims (http://www.lowbudget.com) that is the expert regarding kadrons and has a site dedicated to the Kadrons, maybe he can give you some advice but he doesn't recommend the use of the 009. You can modify the carb to avoid the dreaded 009 flat spot, you need to plug a hole in the butterfly and change jet sizes. I can't remember all the fine details but I have them at home and can pass them on if you're interested, I have done it before and it works, it is also reversable if you're not happy.
http://www.lowbugget.com/main_page.html
http://www.lowbugget.com/help_section.html

Tom Bishop · Post by **Tom Bishop** » Mon Oct 16, 2006 9:27 am

Hi Calooker. Please pass on any info you have. It is all greatly appreciated.

Thanks

vader · Post by **vader** » Mon Oct 16, 2006 10:29 am

This is a very interesting thread please keep us all updated... Doesn't Eddie Brown or his buddies in the States run Kadron carbs? I seem to remember one of them saying something like that.... but hay I could have had my O2 mix wrong that day...

Post by **calooker** » Mon Oct 16, 2006 10:37 am

Check it out, I used a rivet and it worked. Other interesting stuff on this site.
http://www.aircooledtech.com/34pict3_modification/

hitlers revenge · Post by **hitlers revenge** » Tue Oct 17, 2006 8:59 pm

Hey 4agedub, what are your comments. You must surely have one or two after seeing the pictures of the toys that you play with.

vader · Post by **vader** » Wed Oct 18, 2006 5:27 pm

Hal uit en vuis....

Post by **Tony Z** » Sun Dec 10, 2006 11:12 am

Tom

After our lengthy debate about this I took some photos of my 36DCD. It shows the vac line under the butterflys (on the cylinder head side).

Tom Bishop · Post by **Tom Bishop** » Wed Dec 13, 2006 3:27 pm

Hi Tony

I have some pics of the standard solex carb. 34pict3. How do you host your pics. I can't see this option on my page.

I dont know the 36dcd other than it was fitted to the Cortinas and Recored 20 years ago. The only thing I know is I have read threads that the vacuum on these carbs are not great and you need to drill the hole larger. Is this the place you connect the vacuum advance?

The 34pic 3 has multiple tappings, the one on the side for vac advance, the other from the opisite side of the butterfly. From my understanding the US used a dissy with advance and retard, something to do with emission controls.

As far as the 009 myth goes read this link.
http://www.type2.com/library/electrip/advance.htm
Also, why do car manufacturer bother with Vac advance. If they could leave this off and save 1c they would.

But with all this info that I have gained I still have no idea where to tap into my carb. I believe they were fitted to most Brazilian cars of the time and were tapped for the vacuum advance, standard. If somebody has a carb / pic of this tapping please let me have a look.

Cheers

Post by **calooker** » Wed Dec 13, 2006 4:22 pm

Vac advance ignitions are designed to give you smoother accelaration, better consumption, and in some cases regulate emissions when fitted with a retard setup. A 36 DCD weber vac signal is no good for a aircooled VW, it has vac at idle. Idealy on a aircooled motor you need no signal at idle, should come in at about 1000 rpm and tapper off form about 2800rpm, at higher rpm's again the signal should be almost non existant. The type of inlet manifold, cam and other factors also affects a vac signal at the carb.
http://www.thesamba.com/vw/forum/viewto ... hlight=vac
http://www.thesamba.com/vw/forum/viewto ... hlight=vac

Post by **Tony Z** » Wed Dec 13, 2006 6:21 pm

Hi Tom

Go to http://www.imageshack.us and use their functions to host your pictures.
Once this pic has been hosted it will go to a new page. You will get 4 (I think) links above the picture and 4 below it. Copy the first of the lower links into your message in this forum and it will display your pic.

Post by **Tony Z** » Wed Dec 13, 2006 7:09 pm

I agree with you Tom, vac adv is the way to go. As I mentioned to you when we met, the reason I dont run vac adv now is because I have a problem with mine and if I hammer the car, the ignition switches off. I then park the car for 2 minutes and start up again as if nothing happened.

OK, heres how the vac adv works.... and why....

Vac adv is independant of revs. i.e. it doesnt matter what revs you are at, whether it is 1000 or 8000rpm, if your butterfly is closed slightly, the air pressure inside the manifold will be lower than the air pressure in the atmosphere, thus the dizzy will advance. The vac at idle isnt too great, thats why it doesnt advance much at idle, simply because of the amount of time the air has to flow around the butterfly. But if you rev to 4000 and shut the butterfly, the vac is pretty great, causing the dizzy to advance.

The minute you give full acceleration, the pressure in the mainfold is the same as the atmospheric pressure, so the vac adv doesnt advance any more - it doesnt need to. I'll get to that.

Why do you need vac adv at running speed???
When your car is running, it abviously takes in fuel and air. If you fill the combustion chamber completely (full throttle), the mixture burns pretty quickly. If you are running on the highway, at part throttle there is less air fuel mixture in the chamber, which actually burns at a slower rate than the mixture in a full throotle situation. So to get better milage and better fuel consumption, the adv needs to be advanced further, without risking the chance of detonation under full throttle acceleration.
So the mech adv is set to give full throttle acceleration without detonation, and the vac adv is added to adjust the curve for better effiency when at any position other than full throttle.

Why do some cars have vac retard??? I dont know and dont really care. The only time I can think it would be of advantage is in a super or turbo charged car when under boost... the air fuel mixture is even denser, hense the flame travel and pressure build up is faster, necessatating a later ignition to prevent detonation. Other than that, I dont know.