Official Dual Carburetor How To Thread

[AlteWagen]

Solex 40/44 EIS (Kadron) exploded view

Float level setting:

If using factory thin paper gasket use one thin copper washer under needle valve

If using aftermarket thick cardboard gasket use BOTH thick and thin copper washer supplied in rebuild kit.

A few other notes on getting these to run right.

If you cant get the idle mixture to respond make sure you have the correct Solex EIS/EDIS idle mixture screw.

The two on the left are EIS/EDIS mixture screws, the one on the right is a regular PICT type screw which come in universal rebuild kits. Notice the extended shoulder on the EIS/EDIS which is not present on the screw on the right which tapers immediately after the threads end. The EID/EDIS screw is NLA new, used screws are your only option.

Problems with the emulsion tubes are also common on these carbs. If any water was in the carbs it usually plugs up the tube with "white shit" which requires the removal of the jet/tube to be cleaned properly.

Cracked tubes are also common which causes the tubes to drop off the jet and block the main circuit.

Cracks on the bottom of the tube will allow the small plug at the base to fall out causing other tuning problems.

These parts are NLA and usually require a core carb for parts or replacement.

In some cases you can repair the tubes using solder if spares are not available.

Thanks to VintageSpeed (vwtaiwan) for pics of the tubes.

http://www.thesamba.com/vw/forum/viewtopic.php?t=364481

Accelerator pump circuit.

Another common problem area with these carbs is the pump circuit.

-jet tip location
-check ball frozen or missing
-bowl check valve

The tip of the jet is very close to the venturi where the vacuum draws fuel from the circuit causing the "kad drip" making tuning difficult. To fix this remove jet by turning and lifting at the same time (its pressed in not threaded), anneal, and bend to re position tip above venturi opening.

Stock

Modified

Make sure the check ball is under the pump jet, most of the time its missing. There seem to be two sizes of check balls, early carbs use 2.35mm while replacements in the Radke kits for late model measure 3.15mm. YOU CANNOT USE THE LATE ONES IN AN EARLY BODY AS IT WILL BLOCK THE CIRCUIT!

The last area to check is the bowl check valve. Thanks to bobna54oval for the info.

[vaman]

Well, I came to this thread too late. On a 1600 that I use to run, I had no pressure regulator. Back then, I did not even bother to measure fuel pressure. One day, when the car was running really bad, I dropped a valve cover to do a valve job and gas/oil mixture poured out if it. Probably half a quart in all. Carb wash anyone?

On a more recent engine that I built for my son's Ghia, the pressure from a stock pump was indeed 7psi. I installed one of the EMPI regulators. Ten miles later, I get a call saying that the parking lot under his Ghia is awash with fuel. Sure enough, all my fittings were intact, but fuel was pouring out of that center hole of the regulator.

So two questions:
1. If the same needle valve is used in, say, the 34PICT-3 as in Kadrons and PDSITs, why is 5psi ok in one and 2psi needed in the other?

2. What brand is an alternative to the EMPI regulator?

[AlteWagen]

Ive found that the old original solex needle valves are more tolerant to higher pressures while the new valves that come in rebuild kits can only handle 3 or less psi.


As far as regulators I only use Holley on my cars. Kind of a PITA to set up for pressures that low but once done you dont have to worry about it again.

http://www.amazon.com/Holley-12-804-Fuel-Pressure-...lator+blue
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[modok]

If the fuel pump is putting out over 5 PSI then it is not working right, rebuild or replace with one that works right. I recall the pumps putting out about 4 PSI. The fuel pump IS a regulator, you don't need two regulators nor two fuel pumps, but guys do that

One drawback of any engine mounted fuel pump is the tendency to heat the fuel and cause "vapor lock" type problems, if not when running then often flooding the carbs with heat soak after shutoff. The pump has one-way valves so fuel cannot return to the tank, so it overpowers the needle and seat and goes into the carb, which is bad for the environment and your fuel economy, and stinks up your garage. The way around this is a "dump type" regulator that allows to the fuel to return to the tank rather than end up trapped between the pump and carb. Adding such a regulator (or even a return orifice, as used in some 70's cars) to a mechanical pump is possible...... but if a good fuel pump costs over 60$ then frankly it's more practical to use an electric fuel pump such as a carter rotary .........which does solve all three problems at once. Correct pressure, allows fuel back to the tank, and cannot vapor lock.

The fact that pump gas is often now as much as 20% highly volatile stuff toluene/xylene ect.... means that old style fuel pumps that worked fine back when gasoline was made of gasoline may have problems now, even if they are in perfect working order........ oh well, times change

[AlteWagen]

I have not seen any Brosol replacement pumps that put out less than 7psi in the last 5 years. For mechanical pumps I do not use a regulator but as mentioned above add gaskets under the pump to lower pressure. Some like to grind down the rod which does the same thing. I agree there are problems with the pumps from the factory.

I only use electric pumps for dual carbs on my vehicles. The carter pump mentioned is great but on my bus I still have an old Faucet pump that is 22 years old. I have a carter waiting in the wings to replace it but this thing just keeps on going!

this one works great on Dells and Webers but puts out too much for kduds

http://www.summitracing.com/parts/CRT-P60504/
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[vaman]

I swapped my Kadrons for a pair of 35PDSITs because they have chokes. I had to modify the linkage a lot. Now I find that the throttle plates do not return to their closed position because there are no return springs on these carbs.

Anyone else face this problem and solve it?

[dma1260]

Hey - this is a great thread ! Thanks you for all the info.

I got duel 40/44 ESI Kadron's on my 1700 engine. I have 7,000 miles on them, they were running fine up until about 500 miles ago. I started to get a Popping out of my exhaust when I put the engine under a load (lower RPMs) in 2nd and 3rd gear.

I adjusted valves - timing - and mixture screws. Synched carbs (using Uni-Synch tool) got a great idol going, very smooth. But when I step on the accelerator - I get POP POP POP in the same RPM range. Here is my question:

I pulled my .009 distributor and noticed that the shaft is loose - it has some play in it when I spin it. Also it spins with NO resistance. I have a second distributor that I can drop in - but the shaft on the back up Distributor has NO play in it and can be turned easily by hand - but it does have some resistance,
as I mentioned - it can be easily turned by hand. Is this considered normal ? and if my other Distributor is loose - could that cause a misfire ?

Any and all info is appreciated !

Thanks,

Tony

[AlteWagen]

thought I would add this video on carb sync. Sometimes its easier to understand by seeing it in action.


Link

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[AlteWagen]

Dale posted up these sheets from the Pierce site that should help others with the process.

CARBURETOR SET UP AND
LEAN BEST IDLE ADJUSTMENT

It is important to follow all linkage and lever installation instructions. The number one and two reasons for tuning errors are improper linkage installations and over tightened linkage nut, causing a binding in linkage assembly.

CALIBRATIONS MAY VARY DUE TO REGIONAL FUELS AND STATE OF ENGINE TUNE AND PERFORMANCE. POOR RUNNING QUALITY DOES NOT MEAN A DEFECT IN THE CARBURETOR. AN ADVANTAGE OF THE WEBER CARBURETOR IS ITS EASE OF ADJUSTMENT AND TUNING.

SET UP ADJUSTMENTS

Start set up by confirming carb base line settings. Do not depend on the factory delivered settings. Check them before the carb is installed.

All settings are done with choke disengaged or warmed up so that the choke is fully opened and disengaged. This is done on automatic choke carburetors by first opening the choke butterfly by hand and inserting a wood block or wedge of some kind to hold open while the linkage is cycled (linkage operated through its full movement ) to clear the choke cam. (You will hear a metallic click as the cam is released. You can check the fast Idle screw under the choke assembly to confirm that it is not in contact with the choke fast idle cam.)

Set the Idle stop screw (speed screw see fig 1) by backing out the Idle speed screw until it is not in contact with the throttle stop lever. Cycle the linkage again to be sure that the linkage comes to close without any assistance. (Checking for linkage bind) Now bring screw back into contact with the lever and continue to open or screwing in 1 turn no more than 11/2 turns.

Set the mixture screw (see Fig 1) by first screwing in until the screw stops, bottoms out. DO NOT FORCE OR BIND AS THIS WILL CAUSE DAMAGE TO THE SCREW AND IT’S SEAT IN THE BODY OF CARBURETOR. Back out the screw 2 full turns.

TUNING
BE SURE TO FOLLOW THE NEXT INSTRUCTIONS IN THE PROPER SEQUENCE, DEVIATION WILL CAUSE THE CARBURETOR TO NOT FUNCTION TO ITS IDEAL SPECIFICATIONS AND MAY NOT PROVIDE THE PERFORMANCE AND FUEL ECONOMY AS DESIGNED.

4a. Start the engine, the engine will run very slowly more like a tractor. As long as the engine stays running idle speed is not important at this point.

4b. The first thing to do is not set up the idle speed, but to set the Idle mixture screw to lean best idle setting. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). The engine should pick up speed and begin to smooth out. Back out ½ turn more, or until the screw does nothing or runs worse then turn back to the point where it ran its best. Use your ear, not a scope or tuning instruments at this point. You want to tune the engine by sound. Adjust to best, fastest and smoothest running point.

4c. Now that the mixture screw is at its best running location, you can adjust the Idle speed the screw. The screw will be sensitive and should only take ¼ to ½ turns to achieve the idle speed you like. Check and set idle to your driving preference. Put the car in gear and apply slight load, (AC on) and set the Idle as you like it. Don’t set it too high, as this will cause causes excessive clutch and brake wear. The Idle only needs to be 7 to 900 RPM with light load or AC on.

5. Recheck timing and vacuum hook ups. Recheck mixture screw to lean best idle again. If all is still best and smoothest idle then confirm and note the final settings. To confirm settings with the engine running. Start by screwing in the mixture screw and count the number of turns it takes to bottom out and note if the engine dies. If Idle Mixture screws are with in ½ turn of base line setting then all is well and have fun. Also check the speed screw and note how many total turns from initial contact. You may have opened (turned in) the speed screw. Your final setting should be under 2 full turns. Reset the screws (back in) to the best final settings (Per your notes) and go on a test drive and have fun. If the settings are other than described then you may want to recalibrate the Idle circuit (low speed circuit) to your engines needs. This is done by following the rule of thumb BELOW.

Simple Rules for low speed calibration

If the mixture screw is more than 2 1/2 turns out turns then the Idle jet is too lean (too Small). When the mixture screw is less than 11/2 then the Idle jet is too rich (too large). These assumptions are based on the fact that the speed screw setting is not opened more than 11/2 turns. If the speed screw has to be opened 2 or more turns then this is also an indication of a lean condition usually requiring greater change. At times it may appear to be showing signs of richness or flooding it is really a lean condition. See pictures and notes in the tech 2 article supplied in the kit instructions, view and please understand the need to keep throttle plate as near to closed as possible so as not to prematurely expose the transition holes. This is what causes the visible rich condition, and confirms the need to increase the jet size.

EXAMPLE: With the speed screw set at no more than (1 1/2) turns in after contact with the stop lever; and the best idle occurring with the mixture screw set at 3 turns from bottom, indicates the need for a larger Idle jet. Achieving the best idle at under 2 turns indicates the need for a smaller idle jet.



The secret to understanding the critical nature of the carburetor set up and the advantages of a WEBER over other carburetors is the Idle circuit. Referred to as the low speed circuit by Weber, this circuit is responsible for 80% of the driving operation. This is the reason that the Weber should give a fuel economy improvement over most factory carbs along with significant performance gains. In the worst case you should not see a significant fuel economy loss over stock, while improving HP & Drivability.


IDF / DCOE / IDA / 38 DGAS Adjustments
Addendum to lean Best Idle adjustments Notes and adjustments for IDF and DCOE Carburetors


All adjustment procedures are the same as the progressive carbs. It is important to understand the dynamic differences of the two carb styles Progressive and Synchronous carbs Or better described as individual runner carbs.
The progressive idles through barrel and one mixture screw hole, then transitions to a secondary barrel with an additional Idle / low speed jet. The Individual Runner carbs IDF and DCOE have individual Idle jets and mixture screws for each barrel. They also have an additional air bleed screw and lock nut. This is not used for Idle adjustment or Idle quality. The settings for this screw should be closed.
The Main adjustments Speed and Mixture Screw for the individual runner carbs have different values than the Progressive. They tend to be ½ of those used on the progressive

Standard IDF & DCOE Settings

Speed screw ¼ to ½ turn in after contact with lever. Mixture Screw 1 turn out from seated

Follow the same basic procedures as used with the progressive carbs with the exception that there is no choke system and no need to clear the choke cam.

It is important to be very sure there is no throttle shaft bind or over tightened levers. This is the number one reason for most adjustment and tuning problems.

The rules of thumb still hold true the base line settings are only the starting point. The example would be If your mixture screw is out more than one turn like 11/2 turns then your idle jet is too lean go up one half size on the Idle jet not main jet. If you mixture screw is not out one full turn something like only 1/2 turn out from seat then your Idle jet is too rich. This is all based on the important fact that your speed screws are not open more than ½ turn if they are then that is also an indication that you have a lean Idle circuit. You are cheating by opening the throttle plates and exposing additional progression holes in the transition.

These carbs are also commonly used in pairs, this makes the synchronization important please be sure when ever balancing twin carbs to bring the high carb down to the low carb, then bring them both up to proper idle speed demands.
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['72Westy-Betsy]

Hello,

I'm looking to replace the needles and seats in my Dellorto FRD 34 B carbs. I have a few questions that I could really use answers to.

This link:

http://www.cbperformance.com/searchresults.asp?cat=131

takes me to a great exploded view of the carb, it only seems to show one needle and float in the carb, is that all there is? Also is the"seat" the housing that the needle valve sits in? There is nothing called a "seat" in the part diagram...

This link:

http://www.cbperformance.com/ProductDetails.asp?ProductCode=2743

takes you to a rebuild kit for the carb. Is it possible to remove the carb, open the top half of the carb to replace the needle valve and the float, if needed, without having to then reset the air/fuel mixture? Also, will the fuel pump rate be affected by doing this?

If there is a good post that addresses all this please let me know.

Thanks a lot for your posts.

'72Westy-Betsy

[campervan12000]

Hello, I am new to this forum and am trying to pick it up as I go along, be patient, I bought a rail with a running engine and I know the carbs to be Brosols, cos that's whats stamped on them. The distributor is an 050, Any idea of the exact type of carb and the best distributor to run with them? Thanks....

Any advice would much appreciated.
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[AlteWagen]

I personally am not a fan of ANY dual single barrel carbs even the stock carbs that came on type 3s or late type 2s. I would rather run a stock PICT 30 than to spend money on a "stepping stone" type dual carb setup.

Those look to be PDSITs like the ones sold by SCAT and are known to be difficult to tune correctly.

http://scatvw.com/master/carb_kits/solex_carbs.shtml

They have a port to use a SVDA type distributor but not sure if they pull enough vacuum to make it work correctly. All of the current production SVDA distributors are made in china (YES EVEN THE PETRONIX) and have stiff vacuum cans and other issues to work out so beware.


The 050 is an all mechanical advance and was a known as a mileage distributor back in the day but are no longer produced. I personally plot the curve on any used distributor as many are altered or just plain worn out and may damage your engine if not working correctly.

With that setup on a stockish engine it should work OK as long as the carbs are jetted appropriately, synced, and the distributor is working correctly and timing is per spec.

Like mentioned at the beginning of the post if your engine is not healthy the carbs will make it worse.
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[Dan Ruddock]

[mark tucker]

on fishers vid, he should of synchronized all 4 bbls, and set the opening times different,you can't see both sides at the same time, use your finger on one side and look at the other so you can see and feel them both moving/opening at the same time.also oil those moving parts!!!kinda sounded like it might of needed a valve lash adjustment too. but over all it was a good vid for the first timers.also 2 snails are better than one

[advinnie]

After noon all I have a pair of Dell 40 carbs now all four throttle valves are opened the same and all bypass screws are closed. Now three of the barrels have a reading of 6 on my snail gauge but barrel 3 has a higher reading of 7 does this matter?
If so i take it I should open the air bypass screw on its parter barrel number 4 to read 7 as well and then turn the throttle stop screw on the other carb witch both barrels read 6 to increase there rading to 7. Now if I do this the throttle valves/butterflies on this carb will be open more than compared to the other carb does this matter

[Tmagz]

Hey guys! Don't mean to hijack this post but I saw that a lot of knowledgeable, dual carb people, are talking and asking questions on this feed. I couldn't resist asking; Does anyone have any knowledge of dual holleys?

I don't have a lot of money so I get my parts at swap meets. Working on a dual setup for my first motor (1800cc). I noticed that the vw crowd runs a TON on carburation on their cars. How do you run so much carburation on such a small motor and still maintain good pull/idle/throttle response? Thanks guys

[modok]

here is me trying to explain that last week
http://www.thesamba.com/vw/forum/viewtopic.php?t=626072&highlight=120+degrees

[Tmagz]

Thanks, Modok! I liked your posts on that thread, lots of knowledge and funny! I think some of these people do live on venus... I saw that you were talking about creating a formula including cfm. I am currently a mathematics student in college so I may be able to help you play around with that.

Also, I'm getting mixed reviews from people. Do you think that dual holley bugspray 200cfm carburetors (~23.75mm venturies) on an 1800cc vw engine is an appropriate amount of carburation? Max rpm will be about 5500rpm (Don't want to beat the crap out of it) but I do want it to run crisp! Kinda "shut down" the haters out there, you know?

[modok]

The size of the carburetors is OK, however those aren't really intended to be used as "IR carbs". The problems you may run into:
lack of jetting adjustment (no main air bleed and no emulsion tube)
some cylinder running richer than the others if one barrel steals the other's standoff because they don't have separate velocity stacks, and it may go wonky in turns because the float bowls aren't supposed to be side to side. Float bowls are supposed to point forward.

they tried it in the 1970 "the how to hotrod" book and it kind worked. Mark Tucker ran those too and kinda worked. not ideal, but better than a progressive!

[doug80]

I got this set of dual delorto 45 used with the manifolds but after tying to install them the cross bar linkage will not clear the top of the generator, nor is the crossbar long enough to reach the other carb.
Im wondering if i might have the manifolds for weber carbs.. Help