CARBURATOR

[RaduI]

Nu s-a simtit nimeni atins; prin iarna, cand a aparut Lucian pe forum, am zis ca sunt ptr. o restaurare 100% la a lui... facem teorie domne, nu dam cu paru' ! (acum, ca o paranteza, am vazut split-uri pe internet cu motoare de 2000 cmc .... !. Aia au mers pe ideea originalitatii la exterior si accesorii, dar motorul .... unde naiba sa mai gaseasca piese originale?)

Si ptr. ca veni vorba de Hoffmann, unde am comandat, si voi mai comanda, piesele alora sunt Made in Bresil ! Asa ca, ia mai lasati-ma cu originalitatea si calitatea !

[bogdan]

O parte din piesele pe care le-am cumparat erau intradevar din brazilia dar tot pe forumul asta am citit ca VW brazilia a implinit 50 ani.Diferenta de calitate am remarcat de ex. la garniturile pt. motor.In alta ordine de idei depinde de ce vrei de la MASINA ,daca vrei o masina care sa tina pasul cu tehnologia OK eu unul sunt foarte multumit de dinam in vreme ce mai toti au trecut pe alternator. Modificarile facute pe masina mea sunt lampi de semnalizare fata de Raba pastreza forma de si sunt mai mici dar nu am avut incotro pentru ca nu mai am decat o lampa completa dar o sa fac rost si de a doua ,ceas+sonda presiune ulei Dacia si voltmetru la fel.

[RaduI]

Pai vezi ca pana la coada venisi la vorba mea ? Si iti suna mai bine Raba ? O implini VW Brazilia 50 ani, si Dacia Pitesti implineste 40, si ce daca ? Si la ei fac piesele tot diversi furnizori, ca peste tot. Citeam undeva, pe un site frantuzesc parca, era vorba despre pivotii ptr. tipul meu; sfatuiau aia sa ne ferim ca de dracu de piese braziliene ca au calitate proasta, dar de unde sa iau altii, ca nemtzesti n-am vazut ? Si daca or fi, probabil ca costa dublu...

Hai sa revenim la chestii serioase: Cum ai montat sonda de presiune ? Si voltmetrul e rotund, cum aveau la Dacia 1100 ?

[RaduI]

Si la dinam am renuntat ptr. ca era pe 6v initial, mi l-a rebobinat cineva pe 12, si dupa o vreme s-a bulit releul-stabilizator. Timp de 2 ani cat m-am jucat cu dinamul asta, am schimbat 3 baterii !!! Buba la dinamuri e ca baga tensiune de incarcare numai peste o anumita turatie a motorului, spre deosebire de alternator.

[bogdan]

Sonda de presiune am montato printr-o reductie unde era si mono contactul de la ulei deasupra radiatorului de ulei. Atit ceasul de presiune cat si voltmetrul sunt cele rotunde de Dacia 1300 care se gasesc in comertul socialist,am avut noroc ca am gasit un suport cromat de ceasuri care eu zic ca se incadreaza bine cu tot bordul .Voltmetrul L-am pus pt. ca aveam probleme cu dinamul cand mergeam pe camp se strangea praf in el si nu mai incarca esuficient sa-l scuturi de praf si merge.

[RaduI]

Ai pe cineva care stie sa faca reductia aia ca lumea ? Parca acolo e un filet conic..

[bogdan]

Nu este filet conic din cate stiu asta se foloseste numai la gaze ,da cunosc pe cineva ar fi o problema trebuie sa stiu monocontactul ce diametru are la filet si daca ai spatiu acolo sa-l montezi.

[RaduI]

A, corect, uitasem ca tu ai Variant ... Da, spatiu am, nu stiu diametrul, sa ma uit sa vad daca nu o fi la fel ca la Variant .

Filetul conic se foloseste unde apar fluide sub presiune, la fel e si la conductele instalatiei de frana

[Nautilus]

eu unul sunt foarte multumit de dinam in vreme ce mai toti au trecut pe alternator.

Si eu.. odata, cand am ramas cu bateria moarta, dupa 200m de remorcare, dinamul a dat destul curent ca sa actioneze o data electromotorul... deci merge cat de cat :bounce:

. ca aveam probleme cu dinamul cand mergeam pe camp se strangea praf in el si nu mai incarca esuficient sa-l scuturi de praf si merge.

Vezi ca dinamul are si 2 capacele mici si dreptunghiulare de plastic.. si e bine ca ele sa fie acolo unde trebuie - il apara de prea mult praf si apa.

Eu am alta problema la "batranica" mea - consumul, ca inghite cate 11 l/100 km in oras. Cred ca motorul a fost modificat la 1600cc(trebuie sa dau jos capacul de culbutori si sa ma uit la numarul de pe chiulasa, sa fiu sigur), si are un Solex 34 PICT-3, reglat de subsemnatul dupa carte, pe amestec minim. Oare daca-i asamblez un 28PCI din ce am eu, castig ceva? au mai fost "experti" care-mi spuneau sa dau jos cauciucurile de 205 de spate si sa pun mai inguste, ca o sa castig "macar un litru"(!) la consum....

~Nautilus

[alexserb2000]

daca vrei sa vezi ce capacitate ai nu te uiti la chiulasa ca e posibil sa fie de 1300 alezate la 1500-1600....te uiti in capul pistonului si vezi ce scrie...mai ales daca ai luat masina cu motorul gata facut.....astea sunt chestii ascunse care nu se pot vedea decit dupa ce desfaci...cel mult daca nu poti vedea ce scrie in capul la piston masori macar diametrul interior al camasii cu sublerul. Nu o sa obtii un rez de zecime de mm dar vei avea o idee de ce motor ai :ok:

[RaduI]

O parere de "expert" : muta-te din Bucuresti, si ai sa ai consum mai mic in oras...! Pai cand faci 8 km in 40 min., cum fac eu pana la servici, ce vrei domne ??? Ca el consuma si la stopurile multe, si se adauga la cat "papa" in aia 8 km... ar trebui sa masuram consumul / ora, nu /km ...

Dar daca pui un jiclor principal de 125 ? Cat il ai acum ?

[bogdan]

Capacele de care vorbesti nu mai sunt de mult la dinam,da nu face probleme decat cand mergi prin praf dala naspa.

[niq_ro]

incearca sa le faci din textolid subtire si apoi.. scoch la greu, cum am gasit eu la dinamul meu pe 6V ;)

[MikeRG]

Sau daca e sa fii bricoleur si tipicar, niste cleme metalice elastice prinse ca niste gheare in extremitatitile orificiului dreptunghiular al dinamului si cu suruburi pe textolitul respectiv, aproape de sistemul original. Ce ziceti? Ca sa nu mai dam 7 euroi pe un rahat de capac nou. La fel de bine cred ca se poate face ceva mult mai simplu si dintr-un plastic mai rigid, gen damigeana, vorbesc serios! :colors:

[Nautilus]

Dar daca pui un jiclor principal de 125 ? Cat il ai acum ?

Cum fac sa masor un jiclor?

~Nautilus

[victori]

nu prea ai cum, de obicei scrie pe ele ce diametru au

[Nautilus]

nu prea ai cum, de obicei scrie pe ele ce diametru au

Si daca nu scrie? incerc cu un ac, pe care l-am masurat mai inainte cu micrometrul... dar e posibil ca acul sa largeasca jiclorul

~Nautilus

[victori]

nu incerca sa bagi nimic in el ca il decalibrezi

[RaduI]

Da, pe toate pe care le-am vazut scria pe ele, pe capatul pe unde pui surubelnita

[notchman]

How To Put A 28pic or 30pic Carb On An Engine That Is Supposed To Have A 34pic Carb And Not Spend Even Two Dollars- By Chuck Kuecker It's pretty simple. You need a piece of 1/4" aluminum plate and a drill, hacksaw, and files, round and flat. Cut a chunk of plate big enough to cover the bottom of the 34PICT carb. If you take the outline of the flange on the manifold, this is the right shape. Cut the plate to this outline. Next, you need to drill a hole through the middle - 1/2" to start. You will open this hole up with the round file later. You need to make holes for the smaller carb's mounting studs. One of these will be using the original manifols flange hole, the other will be inside the original hole. The small carb should fit on the plate now. Use that round file to open the center hole up until it matches the throat of the smaller carb. The last thing you need to do is remove the front stud from the small carb and get a short screw that threads into the hole there. You are going to bolt the small carb to the plate with this screw. I think you will end up needing a flathead screw, and you will need to countersink the hole at the front from underneath so it is flush with the bottom of the plate. The last step is to make a hole in the front edge of the plate to match the original manifold's hole. This will be pretty close to the mounting hole for the carb, so be careful. This hole needs to be tapped for a stud like the one you just removed from the small carb. Might as well reuse that stud! If you want to 'port' the plate to match the bore of the manifold, you can file a taper into the center hole to do this. The carb mounting screw will be somewhat in the way. The back stud on the small carb might be too short to reach through both the adapter plate and the manifold flange. Use a longer one or a machine bolt to fasten it down. You will need the gaskets for both carbs to seal up the job, or you can carefully apply some silicone gasket maker - try not to let it drip into the engine! Torque everything down, and you are done. The original throttle cable should fit with no changes. Hint - the carb gaskets laid one on top of the other will show you exactly how this gadget should look when done.. After all that typing, I have to say here that I have NOT done this - but this is how I would go about trying! Good luck, if you are brave and try this! Chuck Kuecker Disclaimer: Do this procedure at your own risk.

:)

[notchman]

Cutting out at Idle

Your carburetor is a fuel METERING device. (Many think its only function is to MIX fuel and air, a task largely accomplished in the manifold.) Barring damage due to corrosion or excessive wear of the throttle-shaft bearing, the typical symptom associated with advanced age is for the carb to run TOO RICH rather than too lean.

Since you've not mentioned smoke or other symptoms of rich-running, and since failure to idle is usually the result of improper timing or too lean a mixture -- and since I know you've already checked your timing, plugs and so forth... (you HAVE, haven't you? :-) -- let's take a look at what might produce a lean burn.

Mention 'lean' and the first thing people think of is that the carb must be providing too little fuel -- especially when the problem goes away when you hold the throttle open a bit wider. But the other half of the equation is air. Rather than too LITTLE fuel, you may be getting to MUCH air. Indeed, this is the common cause of this complaint and for a very simple reason.

At idle-speeds the throttle-plate is almost fully closed. This reduces the flow of air thru the carburetor (and activates the low-speed fuel-delivery circuit) but it also lowers the vacuum in the intake manifold, far lower than when the engine is running at maximum rpm. Under those condition it is quite common for the engine to draw in an excess amount of air -- so-called 'vacuum leaks' -- at the gasketed flange under the carb, through leaky hoses, or where the ends of the manifold attach to the cylinder heads.

AND around the shaft of the throttle plate, if the bore is excessively worn.

You can check for such vacuum leaks by squirting a bit of WD-40 on the suspect areas. If they are leaking, the sound of the engine will change when it sucks in some of the WD-40 (which is mostly kerosene). You'll get a bit of white smoke if the leak is very large.

After 27 years of service I would expect your carburetor's throttle-shaft bore to show considerable wear -- and to be sucking excess air at low rpm. This should be the first thing to check. If the throttle-shaft bore is worn, the proper repair is to install a 'bushing-kit', once standard stuff when there was a VW dealer in every town, now so rare most people have never even heard of such kits. (Hold the throttle full open [ie, with the throttle-plate vertical] and see if there is any play where the shaft passes through the casting of the carburetor body.)

Re-bushing a carb isn't difficult -- nowadays they use metal-filled epoxies to hold the new bushings in place. But if you've never done the job and can't find a bushing kit, you're facing quite a task. For a quick fix, build an external 'seal' around the leaky bore using RTV. When the rubber compound cures, you can still move the throttle (albeit stiffly) but the RTV will greatly reduce -- and often stop -- air being sucked in around the throttle- shaft bore (be sure to do both sides).

The other areas where an air leak might occur are easier to repair, the answer being the proper installation of a new gasket, replacement of a hose and so forth.

But as to age effecting your carb, other than internal corrosion or ovaling out the throttle-shaft bore, carbs are relatively 'ageless'. When metering gasoline, wear of a brass orifice is a function of pressure and flow-rate. On a carb, both are quite low. I think you'd need to run about 25,000 gallons of gasoline thru the main-jet before you'd begin to notice erosion of the orifice... and any erosion would tend to ENRICHEN the mixture rather than cause it to run lean (the low-speed circuit draws its fuel thru the main-jet). But the truth is, when running at highway speeds, a good percentage of the fuel burned does not flow thru the main jet but is discharged directly into the carburetor's throat from the spray-bars in the high-power circuit... and from the accelerator-pump outlet. Erosion in these areas would have no effect on low-speed operation.

In any case, the main-jet, pilot-jet (ie, low-speed jet) and emulsion tube are replaceable. IF you suspect erosion, replace them. The cost of a set of jets is a pittance compared to a new carb. But the odds are, they don't need to be replaced.

Contaminants such as dust and rust could cause blockage of the smaller passages in the low-speed circuit and might give rise to a lean idle (usually, they block the circuit completely -- it does not run at all) but the cause of such problems is clearly evident on inspection (ie, rust in the float-bowl [which you can drain & inspect without dismounting or dismantling the carb], rust in the fuel-pump filter, or dust around the upper orifice of the emulsion tube) and responds to proper maintenance -- repair of the fuel tank in the case of rust and of the air-filter with regard to dust. I know you've just cleaned your carb but if the problem had to do with rust or dust, and if you have not dealt with the root problem, you are back to where you were a few weeks ago -- you must clean the carb again. But this time, also take care of the root problem.

The Solex carburetor is more robust than most realize. (And more resistant to blockage. By design, the mesh of the fuel-pump filter is smaller than any of the jets & orifices [pull it out, see for yourself].) But like any carb, your Solex requires its fair share of maintenance. And carbs do wear out, like any other part of your vehicle. But when repairs were needed, Solex carbs were meant to be overhauled, not thrown away.

As to a 30-PICT-3, I think this would be a poor choice for a 1200cc engine. The 28-PCI (ie, manual choke) or -PICT (electric choke) would be a better choice, followed by any of the other 'round-bowl' carbs. The 30-PICT-3 (I think this was the first of the 'square-bowl' carbs) incorporates a special 'low-emission' low-speed circuit. For this new low-speed circuit to function properly there must be a certain minumim rate-of-flow thru the carburetor. At idle, the flow-rate provided by a 1200cc engine is probably too low to insure stable operation of the low-speed circuit found on these 'low- emission' carbs. (The 'square-bowl' carbs were used on the 1500 & 1600cc engines.)

To sum up, your symptoms are most likely being caused by an excess of air rather than a lack of fuel. Before spending any money on repairs, make sure you have accurately diagnosed the root problem. With rare exception, age alone is not grounds for condemning a part, especially one designed to be repaired.

[notchman]

Carburetted Fuel System Specs (Beetle and pre-72 Bus)

1961 - 1963

Type: 28 PICT

Venturi: 22.5 mm

Main Jet: 122.5 mm

Air Correction Jet: 130Y,145Y (Ghia)

Pilot Jet: 55

Pilot Jet Air Bleed: 2.0 mm

Accelerator Pump Jet: 0.050 mm

Power Fuel Jet: 1.0 mm

Float Needle Valve Diameter: 1.5mm

Float Weight: 5.7 grams

Accelerator Pump Feed: 1.1 - 1.4cc/stroke

Fuel Pump

Delivery Pressure (max): 2.8 psi

Delivery Capacity (min): 400cc/min @ 3400 rpm

Air Cleaner

Type: Oil Bath

Oil Capacity: 0.53 pints (0.25 liters)

1964 and 1965

Type: 28 PICT-1

Venturi: 22.5 mm

Main Jet: 122.5 mm

Air Correction Jet: 130Y,145Y (Ghia)

Pilot Jet: 55

Pilot Jet Air Bleed: 2.0 mm

Accelerator Pump Jet: 0.050 mm

Power Fuel Jet: 1.0 mm

Float Needle Valve Diameter: 1.5mm

Float Weight: 5.7 grams

Accelerator Pump Feed: 1.1 - 1.4cc/stroke

Fuel Pump

Delivery Pressure (max): 4 psi

Delivery Capacity (min): 400cc/min @ 3800 rpm

Air Cleaner

Type: Oil Bath

Oil Capacity: 0.53 pints (0.25 liters)

1966 and 1967

Type: 30 PICT-1

Venturi: 24 mm

Main Jet: O 125

Air Correction Jet: 125Z,135Z (1967; Ghia)

170Z (1966; Ghia)

Pilot Jet: g 55

Pilot Jet Air Bleed: 150

Accelerator Pump Jet: 50

Power Fuel Jet: n/a

Float Needle Valve Diameter: 1.5mm

Float Weight: 5.7 grams

Accelerator Pump Feed: 1.3 - 1.6cc/stroke

Fuel Pump

Delivery Pressure (max): 4 psi

Delivery Capacity (min): 400cc/min @ 3800 rpm

Air Cleaner

Type: Oil Bath

Oil Capacity: 0.53 pints (0.25 liters; 1300 engine)

0.8 pints (0.4 liters; 1500 engine)

1968 and 1969

Type: 30 PICT-2

Venturi: 24 mm

Main Jet: O 125

Air Correction Jet: 125Z, 135Z (Ghia)

Pilot Jet: 55

Pilot Jet Air Bleed: 130

Accelerator Pump Jet: 50

Power Fuel Jet: 60

Float Needle Valve Diameter: 1.5mm

Float Weight: 8.7 grams

Accelerator Pump Feed: 1.3 - 1.6cc/stroke

Fuel Pump

Delivery Pressure (max): 4 psi

Delivery Capacity (min): 400cc/min @ 3800 rpm

Air Cleaner

Type: Oil Bath

Oil Capacity: 0.8 pints (0.4 liters)

1970

Type: 30 PICT-3

Venturi: 24 mm

Main Jet: X 112

Air Correction Jet: 125Z

Pilot Jet: 65

Pilot Jet Air Bleed: 135

Accelerator Pump Jet: 42.5

Power Fuel Jet: 100

Float Needle Valve Diameter: 1.5mm

Float Weight: 8.5 grams

Accelerator Pump Feed: 1.2 - 1.35cc/stroke

Fuel Pump

Delivery Pressure (max): 4 psi

Delivery Capacity (min): 350cc/min @ 3800 rpm

Air Cleaner

Type: Oil Bath

Oil Capacity: 0.8 pints (0.4 liters)

1971 - 1974

Type: 34 PICT-3

Venturi: 26 mm

Main Jet: X 127.5

Air Correction Jet: 75Z, 80Z (Ghia)

Pilot Jet: 55

Pilot Jet Air Bleed: 147.5

Accelerator Pump Jet: 50

Power Fuel Jet: 60

Float Needle Valve Diameter: 1.5mm

Float Weight: 8.5 grams

Accelerator Pump Feed: 1.3 - 1.6cc/stroke

Fuel Pump

Delivery Pressure (max): 3-5 psi

Delivery Capacity (min): 400cc/min @ 4000 rpm

Air Cleaner

Type: Oil Bath

Oil Capacity: 0.8 pints (0.4 liters)

1974 (California)

Type: 34 PICT-4

Venturi: 26 mm

Main Jet: x 127.5

Air Correction Jet: 75Z(M), 70Z(A)

Pilot Jet: 55

Pilot Jet Air Bleed: 147.5

Accelerator Pump Jet: 42.5

Power Fuel Jet: 100

Float Needle Valve Diameter: 1.5mm

Float Weight: 8.5 grams

Accelerator Pump Feed: 1.1 - 1.7cc/stroke

[lucian]

notch,

pentru 28PCI nu ai nimic, deoarece am cautat dar fara succes

[MikeRG]

"Stock Solex Jets

28 PCI... with removable Venture... Venturi =21.5 mm... Main Jet = ........ Air correction jet =........Pilot jet = ....... Idle air jet drilling = ...... Power fuel jet = ___..."

si eu am gasit info incomplet... :)

"34 PICT-3...1971-1974... Venturi = 26 mm... Main Jet = 127.5/130... Air correction jet = 75z /80z...Pilot jet =g50/55... Pilot jet air bleed = 147.5...Acc. pump jet = 42.5... Auxiliary fuel jet... =42.5/47.5... Auxiliary air jet = 90...Accelerator pump feed = 1.3-1.6cc/stroke"

"Jetting a Carburetor

Comments:

I'd like to toss out a little info to all the aspiring young carburetor tuners we have here...

There have been a few questions lately as to the availability of jets, especially mains, for the Solex Kadron. (H40/44EIS)

Solex did us a great favor by standardizing the physical size of most of the jets we find in the ACVW lineup. (Physical size here refers to the outer dimensions and thread pitch of a particular type of jet.) Each type of jet (i.e. main...air corrector...etc.) can be had in a range of sizes that refers to the diameter of the drilling.

For instance...you can take the main jet from a 1955 36hp 28PCI and a 1973 34PICT-3 and interchange them....or you can use them in your Kadrons. A great number of air corrector and pilot jets are also interchangeable. The point that I am trying to make is that your best source for a variety of jets in differing sizes for custom tuning can be obtained cheaply from old discarded Solex carburetors. I have approximately 10lbs. of jets that I have saved over the years...if there is something that you can't find.... let me know!

Now...what if someone gives you a jar full of mixed up Solex jets... how can you tell what is what???? There will be letters and numbers stamped into each jet...(A few years ago I could actually read them!)

The number refers to the size of the drilling in 1/100 of an mm. In other words...a g50 pilot jet has an orifice of 50/100mm or .50mm.

The letter codes that you will most often find are:

G - Main jets

a - Air correction jets

g - Pilot jets

u - Pilot jet air bleeds

Gp - Pump jets

s - Emulsion tubes

Now...What if that same nice person also gave you a good Solex carburetor with no main or air corrector jet installed??? How do you have any idea which size jets to pick from your jar???

This is a good base line for any Solex but we'll stay with the Kadron as an example... You will need to know or measure the diameter (in mm) of the Venturi...sometimes called a choke tube. The Kadron comes with a 28mm choke tube....

Multiply the diameter of the choke tube times 5... 28 x 5 = 140 Start with a 140 main jet.... Now add 60 to the number you obtain in the first calculation to determine the air corrector size... 140 + 60 = 200...start with a 200 air corrector jet...It's that simple!

Have fun,

Tom"

"Jetting the Stock Carburetor for performance motors

Jetting the Stock Carburetor for performance motors can involve a lot more then just setting up a stock carburetor for a stock motor. If you bought the stock carburetor for your stock VW you probably won't need the following information. You might just want to change the main jet size. If you have a slightly modified motor then read on. Stock Main jets where generally on the lean side.

If you plan on racing in a stock class where you must use the standard Solex Carburetor then this information will help you get started in the correct direction.

If you have access to an exhaust analyzer with the air/fuel meter your job will be a little easier. Set your jetting a little rich (11.5-12.1:1) on acceleration and about 12.5:1at high RPM.

If you don't have the analyzer then you need to have a reference point to start with. (We would always end up checking out the car with this method after tuning on the Dyno.)

To get this Starting Reference Point, Get a passenger to help you with the spotting and find a stretch of deserted road. You need a starting point to start all runs. With the same passenger in place each time and at a pre-determined starting speed you must start accelerating from the exact same spot traveling at the exact same speed to begin each test run. Depending on your motor select a speed, a little slower then your top speed and take notice at the point along the road you reach this speed. (It can also be helpful to check the time with a stopwatch) Make note of the speed and time and proceed with your jetting. After each run do a repeat run and log the time and speed. We would recommend increasing the main jet size until the speed starts to drop off and then back down two steps smaller.

Main jets can easily be replaced or you can ream out stock jets. Always compare new jets with new jets and reamed jets with reamed jets due to the slight camphor on new jets. Jet drills are not the same, as number drills so don't try to use them. We recommend using the taper reamers. To check the size as you ream, measure the length of the reamer protruding through the jet.

Solex jets are measured in hundredths of a millimeter and come in steps of 2.5 (120, 122.5, 125, 127.5). The larger the number the more fuel the jet will flow. Some jets are measured in flow so don't mix two types of jets. (Weber progressive & Holley Weber for example). Note: VW 120 main jet has a 1.200 mm hole.

Normally you will change jet size by one or two sizes at a time. For example a tuned exhaust would be changed one size at a time, bigger pistons, high lift cam, and higher compression might warrant stepping up several sizes.

If you have a fuel pressure regulator installed, start out with about 3# pressure.

Along with the acceleration runs you should take spark plug readings on the #1 & #3 cylinder.

When taking a plug reading you must run at least 1/4 mile at the desired throttle position. At the end of the 1/4, push in the clutch and simultaneously kill the ignition. Don't change the throttle position until the motor stops completely.

You are looking for a light Tan or Gray coloring on the insulation. Black is rich, white is too lean. Some fuels give slightly different coloring. Instead of gray you might see light brown, but white is always too lean. Remember that a dark or black plug can give poor performance and poor economy but a white or white-blistered plug can burn holes in pistons and size pistons to cylinder walls. So if you error be sure it's on the rich side.

When you get the main jet pretty close start changing the air correction until you have a mid-range slightly rich. Then check the full throttle setting again.

Accelerator pump jets are in the end of the Accelerator pump nozzle, and can make a big difference when the gas pedal is smashed down. You can play around with their size but be sure it is pointing in the right place. You want the squirt between the butterfly and the carburetor body, not hitting the butterfly.

Make sure the throttle is full open when the gas pedal is fully depressed. This might seem very basic but it happens so often, we had to mention it.

Remember as the Venturi size increases the velocity of air through the carburetor decreases. When the velocity of air falls below a certain level the fuel and air cease to be mixed in the correct propositions.

Many times good low end torque will help turn faster lap times then all out horse power.

This is just a start and to be good at carburetor jetting you need to study up on many of the subject we just slightly skimmed over.

TOO RICH > Black sooty plugs / Sluggish performance / Black exhaust smoke / Motor labors at an Idle / Smell of fuel.

Caused by > Too large main jet / Too small air correction jet / Float level too high / Clogged or restrictive air filter / Excessive high fuel pump pressure / Sticking needle and seat.

TOO LEAN > High running temperature / Detonation / White blistered spark plugs / Flat performance / Back firing through the carburetor.

Caused by > Too small main jet / Too large air correction jet / Air Leaks / too little fuel pressure or restricted fuel inlet."

The Evolution of the Beetle

http://beetle.cabriolets.online.fr/tech/evolution.html

Production Changes 1954

1-702 742 (August)

Compression ratio raised to 6,6:1; 28 PCI carburettor, main jet 117.5 and air correction jet 195 (previously 122.5/200).

Production Changes 1958

1 802 775 (January)

Spring for idling screw on 28 PCI carburettor reduced from 13.5mm to 12mm. "

Compilati si voi...

[RaduI]

Gata, ai specificatiile ptr. 28 PCI pe www.r-si-r-doctori-in-broaste.go.ro , la pagina tehnica