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    02/19/03*

                              ---- Weber Progressive Carbs "32/36 DFAV" order

Every now and then some one ask us what the stock jetting for the Weber Progressive is. What jetting comes in the carb when set up for the VW air cooled motor. 

Over the years it changes from one thing to another. So to find out what Jetting Weber is installed at present we checked out one of Webers latest 32/36 DFAV deluxe carb kits and this is what we found.

Primary -----Main = #137 -------- Secondary -----Main = #140
Primary -----Air Corr. = #165 --- Secondary ------Air Corr. = #160 
Primary -----Idle = #60 ----------- Secondary -----Idle = #50

Now don't be alarmed if your new carb has slightly different jetting installed as this should be taken for a starting point only. Yes they will run right out of the box on "All TYPE 1 DUAL PORT ENGINES." but they can normally be made to run a lot better if jetted for your particular motor.

The "INSTALLATION INSTRUCTIONS " that come with the kit states "Using (1) Weber 32/36 DFEV Carburetor "and to no surprise our Kit came with a "32/36 DFAV" carb.  So Lets not get picky about the jetting that was shipped in your carb, because as we said it's only a starting point.

We have found most big problems after installing the progressive carb are due to air leaks or dirt in the carb. But don't forget to check the intake runners for extra instruction sheets, packing material and epoxy from when the runners were glued in.

In years past it was quite common to find the manifold runners a little to long. This can still happen if the crank case has been cut or cleaned up where the cylinders set and / or if the cylinder heads have been cut for added compression. So make sure that when the dual port castings are bolted down that the intake manifold is still a little loose between the end castings.

Dirt in the Carb !! — But my carb is brand new. ?? — How could there be dirt in it. ?? 
This is how it happens. Dirt will build up over time on the inside of the fuel lines ect.. Then when you pull the old line off and even wiggling new fuel line on the fuel pump ect. some small flakes of dirt, fuel line rubber ect. goes in the carb and problems begin. Normally the $1.98 tune up will cure these problems.
The $1.98 tune up is where you rev. the motor up pretty high and slap your hand over the top of the carb. This creates a large vacuum all through the carb and sucks the dirt right out. (Some times very seldom it sucks the dirt in someplace pretty tight but it's always worth trying before a tear down.)

Several things you need to know that we will not cover here is how to take a spark plug reading and what jet affects a particular RPM range. Check your Library or auto parts store for books on Holly and Weber progressive carbs.

We start with checking the float setting as it is critical to tuning the carb. The top & bottom surface of the float should be parallel to the gasket surface of the float bowl. We check the bottom surface of the float by holding the top of the carb upside down at about 45 degrees ( this keeps the weight of the float from compressing the small spring in the float needle ) The gasket surface to the bottom surface of the float should be about 1 1/2" or 38.5mm.

Before you start buying jets lets check out the low speed settings as they will effect your motor from idle to over 3000 rpm.

Back out the idle speed screw ( it's the one on the linkage on the left side of the carb.) Then screw it in until it just starts to move the small primary butterfly ( be sure the choke is full open and place your finger on the butterfly to tell when it first starts to move ) Then turn it in ONE FULL TURN 

Next will set the idle richness screw ( that's the one below the choke on the front of the carb that's impossible to get to.) It controls the amount of pre-mixed air and fuel, Screw it all the way in until it lightly bottoms out and then back it out 2 turns.

Now start the motor and let it warm up without changing either screw setting. Once the motor is warmed up screw the idle richness screw (the hard one to get to) in or out until you find the highest rpm.

Next after letting the motor cool you must check how many turns out the screw is. If the Idle jet size is correct you will be out 1 3/4 to 2 1/4 turns. If you are less then 1 3/4 turns out install a smaller idle jet and if it's more then 2 1/4 turns out you will need a larger idle jet.

If you had to change the idle jet (the one on the left of the choke element) then go back and adjust idle mixture screw again until you end up with it out about 2 turns for the highest rpm. 

We personally back out the mixture screw another ½ turn after doing all the above to richen up the low speed slightly.

After the low speed is adjusted you can start taking spark plug readings to get the main and air corrections spot on.

With the correct size main jet installed the fuel will start dripping from the venture at about 3500 rpm. If fuel starts dripping much higher then 3500 then increase the main jet size. And if it starts below 3500 rpm install a smaller main jet. Use a mirror to check this as it's not wise to look down the carb bore when the motor is running.

Low end throttle response can always be helped with little more initial spark advance but this involves shortening the total advance curve of your distributor. Check out "Set. Timing" as to much total advance is sure death to the VW motor.

We have just touched on some basics to get you started. Many books have been written on tuning the Weber and Holley carbs. So see what the experts have to say and don't jet to lean. To rich and you foul spark plugs and to lean you overheat, size pistons, burn holes in pistons and other nasty things 

About 70% of suspected carb problems that come through our front door are traced to none carb. related problems. And no amount of tuning is going make your motor perform if it's not in tip top condition.

The larger the carburetor on a given motor the more exact the jetting must be. And any little problem with a little carb. is going to be a big problem with a big carb.

Although the Dellorto is no longer imported to the USA we strongly recommend reading their " Dellorto Tech Book" and even though it does not cover the progressive carb. It contains a lot of good information you need to consider when tuning any carb. Every thing from Spark Plug reading to fuel pumps is mentioned and although we do not agree 100% with all that is said in the book , we are also sure you will not agree 100% with all the information we give on this Web-site but it at least it should start you off in the right direction. Have fun tuning that carb. and wave as you drive by.
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