Solex's are easy to adjust when compared to other Porsche induction systems. But they are much harder to adjust than American two barrel carburetors. It takes a certain feel.
Before attempting to adjust the carbs, the following must be correct:
Note: Red type denotes components most commonly used in adjusting carbs
1 - Retaining screw
2 - Passage where high speed mixture enters air stream
3 - Needle & seat (after market shown, original has a spring loaded ball end)
4 - Fuel inlet banjo bolt (hollow bolt)
5 - Cover
7 - Injection nozzle (squirter)
8 - Body
9 - Idle jet
10 - Float level adjustment screw & lock nut
11 - Accelerator pump level
12 - Accelerator pump quantity adjustment nut & lock nut
13 - Accelerator actuation lever
14 - Accelerator pump control rod
15 - Main jet carrier (main jet screws into inner end)
16 - Mixture screw adjustment
17 - Idle stop screw & spring
18 - Throttle shaft
19/20 - Throttle lever
21 - Pump jet
22 - Diffuser (aux venturi)
23 - Air correction jet
Tools Needed to Adjust the Carbs
Adustments Prior to Installation of the Carbs
While the carburetors are out of the car, fill them with fuel by pouring it into the "pipe" in the center of the carb. This accomplishes two things: (1) you will be able to start the car more easily after the carbs have installed and (2) you can adjust the injection quantity while the carbs are on your workbench.
|Another Cheap Measuring Vial
Buy a plastic nose dropper from a local drug store and discard the rubber bulb. Glue shut the small end with super glue or a hot clothes iron. Pierce the side of the vial near the big end and attach about 6" of small wire as a handle. From a local swimming pool supply company or Home Depot buy a small (2") bottle of red or yellow chlorine or pH testing chemical. When turned completely upside down 1 drop of either chemical equals 0.1 cc. Mark your new vial accordingly.
Submitted by Tony Ryan
Place the vial in the throttle bore under the squirter to catch the gas as it comes out of the accelerator pump nozzle. Check manual for correct amount of fuel per stroke -- sometimes it's more accurate to use a number of strokes and divide by the number of strokes. When stroking the throtle, open the throttle smartly and hold open until squirting has stopped before attempting another stroke.
The injection quantity can be varied by adjusting the length of the stroke using the nuts on the accelerator pump adjustment threaded pull rod (#12).
Note: Many believe that the factory settings are too high for todays gas, and can cause a flat spot upon acceleration. You may want to experiment with using a somewhat lower volume.
One more thing to do before you install the carbs. Go ahead and make the initial adjustment of the mixture screws (#16). Turn until fully seated, then turn 1 1/2 turns back out.
Preparing to Install and Adjust the Carbs
These instructions start with the engine thoroughly cleaned and manifolds installed with new gaskets. The linkage should be clean and high temperature grease added to the ball sockets. An 8mm open end wrench can be used as a ball joint separator. New gaskets are used between the manifolds and spacers and between the spacers and the carburetors (use only genuine Porsche or equal gaskets. A new gasket should go between the carburetor and the air cleaner.
Next the linkage should be hooked up, except for the short ball jointed pull rods. Find the idle stop screws and turn them out until the throttle plates rest against the throttle bores. Now turn the screws in until they just touch the throttle arm, and then turn 1/2 turn more. Now adjust the pull rods so that they can be snapped on without disturbing the throttle setting. This should give the carbs side to side balance. Now snap on the pull rods.
Oil the throttle shafts and accelerator pump linkage (and redo everyb 3000 miles) and check for smooth operation. Next, have someone get inside the car and floor the gas pedal while you are looking into the carbs. This is to make sure that the throttle plates open all the way to vertical (but be sure they don't go past vertical).
You can now hook up the fuel lines. If the original braided fuel hose in the line to the carbs is old and ragged, and you don't want to buy the complete set-up from Porsche, you can remove the entire assembly from the car, cut about 1/2" from the metal lines, and install regular neoprene fuel hose and "European" type hose clamps. Don't forget the filters. The German VW Type 3 fuel hose is safer than the stock hose. Be sure to check the metal lines for wear if they rub on sheet metal, etc.
Adjusting the Carbs
Adjust the fuel level by means of the float level adjustment screw (#10) immediately above the accelerator pump block. Loosen lock nut and turn in to lower fuel level, turn out to raise the fuel level. You should take your time with this as the bowl is large and it takes a while for it to stabilize. When turning in the screw, do so slowly, as you may bend the elevator if you go too fast. Lock the adjusting screw when finished. After setting the fuel level, don't forget to remove the jet from the tool and install it back into its carrier. Do both carburetors.
Alternative Method that does not require use of the Porsche special tool.
There is a small bolt located at the top middle of the fuel bowl, on the side of the carb facing the engine. Carefully remove this bolt (good idea to put a rag underneath as it's easy to drop and easy to lose). If no fuel drips out, then you turn out the float level adjustment screw (#10) slowly to increase the level of fuel in the bowl. At some point a bit of fuel will drip out of the hole. At that point, turn the float level adjustment back in just to the point where fuel no longer drips out.
If the engine doesn't respond when you turn one of the mixture screws in and out, it means that the cylinder is not getting ignition, or it is not getting mixture. If the ignition and compression check out, then an idle passage is plugged. Remove the mixture screw and spring and blow comopressed air into the mixture screw hole to clear the obstruction. (Caution: DO NOT blow into the top vent.) If this doesn't work, then the idle passage may need to be "boiled out" or the passage checked with a duct gauge.
Adjust the other barrel of the carburetor to an equal vacuum using the small screw below the fuel bowl and between the throttle bores.
Solid Shaft Carbs
You must hold the throttle lever and by means of a 5MM open end wrench on the forward end of the shaft and twist shaft in appropriate direction to create equal vacuum. Be sure the throttle is open a small amount when twisting shaft so as not to jam the throttle plates in the bores. Do both carbs.
Sometimes as you turn the screw out, it speeds up the engine enough to advance the timing, which adds 300-400 RPM. When you turn the idles screws back a hair to correct this, the weights in the distributor flop back, which slows the engine. This may mean that you need a distributor rebuild. It's best to get your initial adjustment around 1000 RPM and hope the distributor doesn't intercede.
Be sure to check the side to side balance each time you adjust the idle screws. remove the right pull rod.
This is part of our module on how to tune up your 356. Components include: