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oprn
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PostPosted: Sun Jun 24, 2018 5:17 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Good afternoon all!


I just want to share a little trick that helped me in balancing a pair of Weber carbs.

The background to this is they are on a Manx copy and are a tight fit under the body. Anything I do to these carbs entails that they have to come off the engine to be worked on. This includes jet changes as well as just simply servicing the air cleaners. Every time the carbs come off the linkage has to be re-set up and balanced. Now to balance them you need to use a snail - correct? But - the air cleaners have to come off which means the carbs have to be removed which means you have to rebalance the carbs...

Get the picture? Doesn't work!

So - enter the biker's trick - the bottle and tube method with fluid in both and lines hooked up to the intake on each side. Fluid all buggers off into one bottle, ok which side is the lazy one? Adjust it a bit, hook it up and the fluid buggers off again - needs more. Try again now the fluid takes off for the other bottle - dang too far. And back and forth it goes. Just can't get it close enough to have time to tinker before the fluid changes sides.


Brain wave hits! Use the heat gun on the exhaust dummy! Yes! One side at 290*F and the other is 570*F. I know which side is lazy now! Turn the idle stops a bit and wait - better? Worse? Tweak. Pretty soon we have them within 50* of each other.


Now hook up the bottles - much better, the fluid is now changing sides slow enough to be able to adjust without it going all to one side before you can reach for the screw driver. A few more minutes and it is good, both bottles equal and staying.


Now hook up the down links and run it up to a fast idle. Watch which bottle drops, adjust that link length etc. Try it again... adjust - soon it's all good.

Not sure if anyone can follow that but it sure helped me to rough the linkage in and get it close enough to final adjust by the bottle method.

Oh and by the way when I was finished the exhaust pipe temps were within 5*F of each other. Interesting don't you think?
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PostPosted: Tue Jun 26, 2018 2:17 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Anyone know of a good place to have some dual dell 45s massaged and tested?
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PostPosted: Mon Jul 02, 2018 5:10 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

I have been using this thread for some time and it has been a big help, thanks for all the information.

I just cleaned and rebuilt my Weber 44 IDF's and forgot to write down how far the Air Bypass screw and jam nut was backed out. What is the typical setting?

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F11 emulsion tubes
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PostPosted: Wed Jul 04, 2018 8:20 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Great info from John.

If the idle jet is sized properly the idle mixture screws will be out more to get the proper idle mixture, and the mixture will also be correct on progression.

If the idle jet is too big, your idle mixture screws will be in too far (barely cracked) at idle, and while it will have the proper idle mixture it will be very rich on progression.

If the idle jet is too small, the idle screws will be way out at idle (proper idle mixture), but will be way lean on progression.

Weber is not stupid. When the idle jet is sized properly the idle mixture screws will be in a specific range, and will work properly on progression.
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PostPosted: Wed Jul 04, 2018 8:26 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

oprn wrote:
Good afternoon all!


I just want to share a little trick that helped me in balancing a pair of Weber carbs.

The background to this is they are on a Manx copy and are a tight fit under the body. Anything I do to these carbs entails that they have to come off the engine to be worked on. This includes jet changes as well as just simply servicing the air cleaners. Every time the carbs come off the linkage has to be re-set up and balanced. Now to balance them you need to use a snail - correct? But - the air cleaners have to come off which means the carbs have to be removed which means you have to rebalance the carbs...

Get the picture? Doesn't work!

So - enter the biker's trick - the bottle and tube method with fluid in both and lines hooked up to the intake on each side. Fluid all buggers off into one bottle, ok which side is the lazy one? Adjust it a bit, hook it up and the fluid buggers off again - needs more. Try again now the fluid takes off for the other bottle - dang too far. And back and forth it goes. Just can't get it close enough to have time to tinker before the fluid changes sides.


Brain wave hits! Use the heat gun on the exhaust dummy! Yes! One side at 290*F and the other is 570*F. I know which side is lazy now! Turn the idle stops a bit and wait - better? Worse? Tweak. Pretty soon we have them within 50* of each other.


Now hook up the bottles - much better, the fluid is now changing sides slow enough to be able to adjust without it going all to one side before you can reach for the screw driver. A few more minutes and it is good, both bottles equal and staying.


Now hook up the down links and run it up to a fast idle. Watch which bottle drops, adjust that link length etc. Try it again... adjust - soon it's all good.

Not sure if anyone can follow that but it sure helped me to rough the linkage in and get it close enough to final adjust by the bottle method.

Oh and by the way when I was finished the exhaust pipe temps were within 5*F of each other. Interesting don't you think?
Where the photos or video? Cool
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PostPosted: Wed Jul 11, 2018 3:56 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

I will be doing another jet change in the near future and try to get a few pictures then. As for a video... not sure if I am tech-y enough to do that...
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PostPosted: Wed Jul 11, 2018 5:12 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Here's a Youtube video of what oprn made. Pretty easy to use if you have a vac port on each carb throat.
https://www.youtube.com/watch?v=Y_WDF6glD5k
Good Luck.
APPLEGREENVW wrote:
oprn wrote:
Good afternoon all!


I just want to share a little trick that helped me in balancing a pair of Weber carbs.

The background to this is they are on a Manx copy and are a tight fit under the body. Anything I do to these carbs entails that they have to come off the engine to be worked on. This includes jet changes as well as just simply servicing the air cleaners. Every time the carbs come off the linkage has to be re-set up and balanced. Now to balance them you need to use a snail - correct? But - the air cleaners have to come off which means the carbs have to be removed which means you have to rebalance the carbs...

Get the picture? Doesn't work!

So - enter the biker's trick - the bottle and tube method with fluid in both and lines hooked up to the intake on each side. Fluid all buggers off into one bottle, ok which side is the lazy one? Adjust it a bit, hook it up and the fluid buggers off again - needs more. Try again now the fluid takes off for the other bottle - dang too far. And back and forth it goes. Just can't get it close enough to have time to tinker before the fluid changes sides.


Brain wave hits! Use the heat gun on the exhaust dummy! Yes! One side at 290*F and the other is 570*F. I know which side is lazy now! Turn the idle stops a bit and wait - better? Worse? Tweak. Pretty soon we have them within 50* of each other.


Now hook up the bottles - much better, the fluid is now changing sides slow enough to be able to adjust without it going all to one side before you can reach for the screw driver. A few more minutes and it is good, both bottles equal and staying.


Now hook up the down links and run it up to a fast idle. Watch which bottle drops, adjust that link length etc. Try it again... adjust - soon it's all good.

Not sure if anyone can follow that but it sure helped me to rough the linkage in and get it close enough to final adjust by the bottle method.

Oh and by the way when I was finished the exhaust pipe temps were within 5*F of each other. Interesting don't you think?
Where the photos or video? Cool

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PostPosted: Wed Jul 11, 2018 8:07 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Interesting method, though the guy is using it to adjust the idle screws, yet he synced the movement of the throttles before.
Is the vacuum port on a Weber iCT usable with this setup?
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PostPosted: Thu Jul 12, 2018 4:45 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

The bottles in the video link are set up the same way and I use water in them with 4 drops of food coloring for visibility.

Yes my carbs have a vacuum test port on each barrel below the throttle plate just for this purpose. I put the little yellow tubes on them with ball plugs thinking they would leak air but found it not necessary because you have to loosen the fittings with a wrench to get a reading anyway. The larger fitting on the right barrel just above is for vacuum advance and is only on that one barrel. The other side does not have one.


All Webers may not have these but it would be simple enough to drill and tap them if the bosses are there or even drill and tap the manifold just below the carbs.

Image may have been reduced in size. Click image to view fullscreen.
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PostPosted: Sun Jul 15, 2018 6:08 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

I will see if pictures clarify how I do this.

Jets changed, carbs back on, one carb down link unhooked. This is where I tie in the bottles. One on the right, one on the left. I used the two rear cylinders.

Image may have been reduced in size. Click image to view fullscreen.
Now-

Connect the bottle - yup all the fliud goes one way fast.

Image may have been reduced in size. Click image to view fullscreen.


The quick way to get a starting point is to ignore the bottles at this point and get out the heat gun. Again just checking the back two cylinders,left first. 555*F

Image may have been reduced in size. Click image to view fullscreen.

now the right. 198*F

Image may have been reduced in size. Click image to view fullscreen.


The lazy one is obvious so open it up with the idle speed screw, go back and forth on the idle speed screws until the idle speed is on target and the temps are close. Don't rush it takes a bit of time for the temperatures to change after each adjustment.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.


Voila! The fluid in the bottles is now close and moving slowly enough to give me time to adjust things.

Image may have been reduced in size. Click image to view fullscreen.


A wee touch at a time and watch for movement in the right direction and pretty soon its right on!

Image may have been reduced in size. Click image to view fullscreen.


Now hook up the down link, throttle it up with the throttle center pull bar until the carbs are off the idle stops and watch the level. Lengthen or shorten a rod until the bottles stay in the center when throttled up and you're done!

Make sense?

Works for me! You old timers feel free to chip in if I missed something or can improve on this way of doing it.
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PostPosted: Tue Jul 17, 2018 4:40 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Thanks for the photos. I saw this kit available from CB. Will this work on 40,44 IDF's intakes?


http://www.cbperformance.com/product-p/2040.htm
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PostPosted: Fri Jul 20, 2018 4:41 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

That is the right idea but they do not say what carbs it fits. With a 50 mm inside bore I suspect they fit 48 mm carbs. You will have to contact them to see if they have the correct size for your carbs.
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PostPosted: Fri Jul 20, 2018 6:06 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

APPLEGREENVW wrote:
Thanks for the photos. I saw this kit available from CB. Will this work on 40,44 IDF's intakes?

http://www.cbperformance.com/product-p/2040.htm


Isn't that more an adapter to measure the MAP if you're running crank trigger ignition for instance?
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PostPosted: Fri Jul 20, 2018 10:46 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

I think people are saving money by just tapping ea manifold runner and adding a small barb or pipe/epoxy.
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PostPosted: Sat Jul 21, 2018 7:02 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

According to the add it is for a vacuum take off to run the advance pot on the distributor. Not the ideal way to do that in my view. It should work fine for carb balancing ports though.

Yes you could drill and tap the intake or the carbs for that matter.
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PostPosted: Fri Oct 05, 2018 3:46 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

I want everyone to help me.
I have seen several Kadron so far.
I also saw the outer venturi.
A small hole was drilled in the outer venturi of EMPI purchased this time.

I'd like to know why this hole was opened.

① and ② are connected.
② and ③ are assembled and connected.
③ and ④ were blocked because the venturi had no holes.

I do not know why it is necessary to change the amount of air flowing into the carburetor using the hole of ④.

Why is there no open hole?


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PostPosted: Tue Nov 13, 2018 10:33 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Thought I would add this here as it shows current manufacturing and assembly issues with the HPMX carbs. I also experienced porosity in a set of 34 EPCs a year or so after they were released, I would have thought they had the issue resolved by now.

At least the vendor replaced the faulty part but in typical EMPI fashion it was with another faulty part.


Machinist wrote:
I purchased a set of 44 HPMX carbs for my new 2276 build and have found some problems that I would like to share with the group. First problem was fuel running down the throat of #1 with some leaking around the throttle shaft and some around the throttle plate to the combustion chamber. I tried all the normal fixes such as float level, bad needle and seat, bad float, too much fuel pressure, fuel tank mounted above level of carbs, etc. Finally found the problem. There was porosity in the bore behind the venturi. A couple of the pitts were right at the side of the jet stacks and would allow fuel to leak into the throat. I contacted the seller and they replaced the carb. Next problem was with the replacement they sent me. For some reason I could not adjust #1 idle mixture. The plug was burning very rich and even completely closing the mixture screw had no effect on idle. The mixture screw on #2 was less than perfect but not as bad as #1. Again I tried all the common suggestions but none helped. I knew the problem had to be below the throttle plate as I was only 1/2 turn on throttle stop screw. Finally found it. I removed the spring from the mixture screw and lightly seated it. Poured liquid soap around the seat from inside the throttle bore and blew low air pressure from the vents in carb top. The brass idle mixture seat was leaking around the outside into the bore. Looking closely with magnifying glass shower a gap slightly off center between the brass seat and the aluminum throttle bore. Looking from the outside where the mixture screw threads in it appeared that the seat threaded in as there were slots machined into the brass seat. I know that some of the Italian carbs use a replaceable seats but these would not budge. I didn't want to wait for carbs to be mailed back again so I squirted some loctite around the brass from the inside and after that dried took a toothpick and put a very small bead of JB weld around the jets of both carbs just to be sure. The carbs respond perfectly now and the motor runs better than it ever has! I'll add photos soon.
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PostPosted: Tue Nov 13, 2018 10:42 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

J-ZEAL wrote:
I want everyone to help me.
I have seen several Kadron so far.
I also saw the outer venturi.
A small hole was drilled in the outer venturi of EMPI purchased this time.

I'd like to know why this hole was opened.

① and ② are connected.
② and ③ are assembled and connected.
③ and ④ were blocked because the venturi had no holes.


Sorry didnt see your reply.

I thought #1 was the idle jet air bleed restriction. I have no idea what #4 does or why its needed. You must remember that the Solex EIS was originally used on a Brazilian Jeep in the 70s. Seems some of the vacuum port passages are emission type ports, maybe also emissions related?

I will have to go take a look at some cores to see if they match what they look like.
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PostPosted: Thu Jan 17, 2019 4:26 pm    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

I just tried these Weber IDF 40mmX28mm carbs that came off of a Porsche 912 on my Spare VW Engine it's a 1.8 Liter Type 1. Doesn't seem to run very well with them! (Missing and popping on carbs during the transition.) I think the idle jets are acting up too. What jetting would be good? (I want to stay with the 28mm Ventures because it's going into a Bus or I may put these carbs on 1679cc.)

1800cc (Type1)
Altitude Sea Level to 500'
Cam Webcam grind#118, 245'@.050" .460 valve lift with 1.25 Ratio Rockers
Stock 35.5X32mm Valve Sizes
8.6:1 CR
28mm ventures
210 Main Air?
115 Mains
50 idles
F7 Main Emulsion Tubes on short holders
80 F5 Idle tubes
50 idle jets
Pump Jets? (Seem Small!)

The Dells, drla 36's that ran well on this engine had:
Venturi: 30mm
1.80
Mains: 1.32
Idle: .55

Spare VW Engine:
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PostPosted: Fri Mar 08, 2019 7:49 am    Post subject: Re: Official Dual Carburetor How To Thread Reply with quote

Good morning all. Thought I would bump this outstanding thread with another newbie question.
I recently acquired a set of Spanish Weber 44idf carbs from CL and was wondering if the consensus could advise me. I have a stock 1600dp running a 009 distributor. Can these two carbs be set up on my small motor and be jetted/tuned to function well? Or are they simply too big? Many thanks in advance!
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The extra tubes in this pic comes from the previous owner attempting to run them on an 80 cu.in. Harley!
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