The single shaft Solex 40 PII were first used by Porsche in the 1955 1500cc Carrera
engines installed in the 356. The 40 PII-4, came with the first Super 90 engines in late
1959. It was chosen because of the increased performance parameters of the Super
90. The 28mm venturi size of the Zenith 32NDIX used on the 1600 Super engines was
not large enough to support the extra breathing capacity of the Super 90 engine. In
addition to this need for larger venturis, the Solex has an enrichment device that kicks in
at higher rpm. More fuel is required at the higher rpms and the air correction jet alone
cannot provide enough.
Split Shaft vs Single Shaft
As the name implies, the original Solex 40 PII-4 had one single solid shaft,
in each carburetor holding the two butterflies.
The split shaft consists of two independent shafts, each controlling a single butterfly, in
each carburetor. There are also different idling circuits and jetting. The latter makes for
better overall performance..
Solex originally designed the split shafts for Porsche for the late 912 series, to address
stricter emission control regulations that came into effect during the late 1960’s. The
split shaft Solex, compared to the solid shaft version, has a better transition from idle to
main jet operation. When one looks at the bottom of the carb and opens the butterflies,
you will notice a series of holes called by-pass holes or ports. On split shafts, there are
5 of these compared to the 3 on solid shafts. These additional by-pass ports, along with
the different idling circuit, give the split shaft Solex the smoother transition from idle to
main jet operation.
Split Shaft Weak Point
The split shaft Solex’s two independent shafts are controlled by a central mechanical
device made of pot metal, which synchronized the butterflies so the airflow is equal in
each throat. When these carbs were new, this device worked well. Now, being almost
40 years old, these devices are broken, worn, have rusty screws, and the plastic block
degredates, so ultimately, there is little butterfly control. This mechanical device also
added to the complexity of the carburetors, making them difficult to
rebuild and maintain, plus requiring a certain skill level to tune that
many owner/operators haven’t yet acquired.
We now do split shaft restorations by special order only. The
cost will be based on an hourly rate due to the lack of availabililtly
of these parts and the complexity of their set up.
An alternative
engines installed in the 356. The 40 PII-4, came with the first Super 90 engines in late
1959. It was chosen because of the increased performance parameters of the Super
90. The 28mm venturi size of the Zenith 32NDIX used on the 1600 Super engines was
not large enough to support the extra breathing capacity of the Super 90 engine. In
addition to this need for larger venturis, the Solex has an enrichment device that kicks in
at higher rpm. More fuel is required at the higher rpms and the air correction jet alone
cannot provide enough.
Split Shaft vs Single Shaft
As the name implies, the original Solex 40 PII-4 had one single solid shaft,
in each carburetor holding the two butterflies.
The split shaft consists of two independent shafts, each controlling a single butterfly, in
each carburetor. There are also different idling circuits and jetting. The latter makes for
better overall performance..
Solex originally designed the split shafts for Porsche for the late 912 series, to address
stricter emission control regulations that came into effect during the late 1960’s. The
split shaft Solex, compared to the solid shaft version, has a better transition from idle to
main jet operation. When one looks at the bottom of the carb and opens the butterflies,
you will notice a series of holes called by-pass holes or ports. On split shafts, there are
5 of these compared to the 3 on solid shafts. These additional by-pass ports, along with
the different idling circuit, give the split shaft Solex the smoother transition from idle to
main jet operation.
Split Shaft Weak Point
The split shaft Solex’s two independent shafts are controlled by a central mechanical
device made of pot metal, which synchronized the butterflies so the airflow is equal in
each throat. When these carbs were new, this device worked well. Now, being almost
40 years old, these devices are broken, worn, have rusty screws, and the plastic block
degredates, so ultimately, there is little butterfly control. This mechanical device also
added to the complexity of the carburetors, making them difficult to
rebuild and maintain, plus requiring a certain skill level to tune that
many owner/operators haven’t yet acquired.
We now do split shaft restorations by special order only. The
cost will be based on an hourly rate due to the lack of availabililtly
of these parts and the complexity of their set up.
An alternative
Solex Split Shaft Conversion
We found a way to convert the split shaft to a single shaft
eliminating the mechanical device. In our modified version, the single shaft is
made from chrome-moly steel and supported by four bearing bronze bushings
(originals were brass). Now you can have all the advantages of the split shaft
Solex; extra power and smoother transition, with the relative ease of adjustment
that single shaft Solex are known for. In addition to new shafts, bushings and
butterflies, these conversion carburetors include 8 newly manufactured
accelerator pump parts to provide reliable smooth carburetors..
eliminating the mechanical device. In our modified version, the single shaft is
made from chrome-moly steel and supported by four bearing bronze bushings
(originals were brass). Now you can have all the advantages of the split shaft
Solex; extra power and smoother transition, with the relative ease of adjustment
that single shaft Solex are known for. In addition to new shafts, bushings and
butterflies, these conversion carburetors include 8 newly manufactured
accelerator pump parts to provide reliable smooth carburetors..
Attn: late 912 Owners!!
One of the best features of these split shaft conversions is that we retain the
rest of the split shaft hardware, so your carbs still have their original look.
Especially important for display and concours competition. As you can see
from these pictures, we also are able to offer you the original gold color look for
your period vehicle. Please contact us for details.
One of the best features of these split shaft conversions is that we retain the
rest of the split shaft hardware, so your carbs still have their original look.
Especially important for display and concours competition. As you can see
from these pictures, we also are able to offer you the original gold color look for
your period vehicle. Please contact us for details.
The gold color you see in this photo is available only by special order, |
| 356 Carburetor Rescue, 285 Morgan Road, Sedona, Arizona 86336 Call Jim or Candace at 928 204-0507 for pricing information on our products and services Call John at 619 224-3566 for technical information or installation help on the carburetors If you have problems with this website, contact Candace at cdelaney@356carburetorrescue.com or call 928 204-0507 Thank you for your interest in our products |
