Setting the butterflies in the throttle
body - Solex 40PII Carburetors
When you receive your throttle bodies, included is a selection of shims for setting the shafts
and butterflies properly. These shims are 0.1, 0.2, 0.3, and 0.5mm, two of each.  
note, we have now started adding some of these shims to the shaft and synchronizing the
butterflies. You will still have to follow the procedure for adding your end hardware and
checking the airflow after final assembly.

We are including the installation of shaft hardware when supplied with throttle
body restoration.  If it has not been supplied and you are setting up your own
carburetors, please follow these instructions.   A copy will be included with
your throttle bodies.

This procedure requires the use of the end of shaft hardware in your possession. We have
found each set of hardware is a little different from the next, so this can only be done with
your carburetor’s unique parts.  First, mount hardware, with one of the shims, on the end of
the shaft pointing towards the front of the car. Check for binding.   

Open the butterflies slightly to check the clearance, then close tightly. Now loosen the
butterfly screws, keeping the butterflies closed in the bore (they will slide out of place if not
careful). Install a shim on the opposite end under your throttle arm and nut. We like to shoot
for setting the shaft end play at 0.1mm on each end. Check this again with the butterflies
open in the bore, moving the shaft back and forth. You are looking for 0.15 - 0.2mm total
clearance.  Proper end play will prevent the butterflies from gouging the body again.  It might
be necessary to repeat procedure between ends until you get the right combination of
shims.  There should be no binding once all is tightened. If there is any, loosen the hardware
and install a smaller shim, as needed.   Yes, it takes a long time to get it done right, even by
the “experts”!

Then, check to make sure your butterflies are sitting properly in the bore. Tighten the screws
holding the butterflies in place. Hold the carburetor up to the light, looking down the bore.
There should be minimal light leakage around the edge of the butterfly, as they are cut
slightly smaller (about 0.03-0.04mm) than the bore. If you see too large a gap, you will have
to loosen the butterfly screws again, turn the butterfly in the bore slightly left or right, closing
that gap. Tighten screws and check with the light down the bore again. If you get this right,
you won’t need a flow bench to check air volume of each throat. Be patient, its important for
the smooth operation of your carburetor. Try to do your best, it can be frustrating to get
everything aligned properly!

As a final check, to simulate engine temperature, put the carbs in an oven at 200 F, then
check the shaft movement and butterfly fit.  If there is binding, go back and check what is
causing the problem.

If all is well, and you are satisfied with the way the butterflies are sitting in the bore, one at a
time, remove the butterfly screws, and secure them with blue or red locktite. Make sure you
use enough, if they fall out, it will go right into the combustion chamber.  As an extra
precaution in our restorations, the ends of the screws are  peened over. This is done with a
piece of metal  under the shaft screws, then taking a long screwdriver and pounding the
screw end. You will see the end of the brass screw open up just enough to make it difficult for
them to fall (or be taken) out.

Now you can proceed as with any other rebuild. There is a
Solex parts diagrams, and work
shop manual pages available if you need them.

At any point, if you have questions,  call or e-mail Jim or Candace at 928 - 204-0507.