Completely restored Weber 40 IDTP carburetor set, serial numbers 3573 and 3446. “SOLD”

This set of carburetors started life as a genuine set of Italian-built Webers that were delivered to Porsche for fitment in the new car production of 1969 through 1971 911 T Models. Both of these carburetor bodies are sporting the Genuine Porsche parts emblem stamped into the front of the main carburetor housing.

The Weber 40 IDTP 3C is the last iteration of the Weber carburetor to be used on the Porsche 911 models. These carburetors were the result of the previous 5 years of the Weber IDA type carburetor. A number of features changed with this carburetor:

• New design throttle levers that allow for more accurate idle speed adjustments
• Updated the old throttle shaft coupling from a stamped steel coupling to a solid machined steel coupling
• The accelerator pump linkage changed to an adjustable linkage instead of a fixed link
• A new style pump cam was introduced, eliminating the delay in fuel delivery with slow throttle movements
• The inlet exhaust check valve for the accelerator pump circuit was changed to a 0.00 size to work with the adjustable linkage.
• The mixture control circuit changed along with a revised progression port sizing.

To see more information on the different types of Weber carburetors used on Porsche models, you can watch our video on the subject here.

The Carburetor Restoration Process

We have been working with and restoring Porsche carburetors for the last 30-plus years. Over that time, we have refined our process of repairing these 50-plus-year-old parts.

The process starts with a complete disassembly. This includes removing all the studs, throttle shafts, and throttle plates. The lead plugs that seal the progression port passageways are also removed to allow for the cleaning of the passageways.

First Steps After Disassembly

Once the carburetor is, disassembled, parts are sorted into different categories. The steel parts are washed and inspected for wear and damage. The items that are reusable are sent to be re-plated to an original zinc finish. Zinc alloy parts like the auxiliary boosters and fuel pump distribution blocks and cleaned. Then vapor blasted, and media tumbled. The brass parts are also cleaned, vapor blasted, and media tumbled. Lastly, the aluminum throttle body housing and top plates are washed and vapor blasted, then media tumbled.

Once all the different parts have been cleaned and inspected, the process of bringing these carburetors back to life begins.

Machining the Weber 40 IDTP Carburetor bodies and top plates

Now that the carburetor bodies are clean, it’s time for the machine work to begin. Years of use coupled with numerous mechanics of varying skill levels can take their toll on the bodies. The top plate gasket surfaces are machined along with the base gasket flanges. The progression port passageways are scrubbed with a small bottle brush to ensure that the passageways are free of restriction.

The top plate housing is also machined on both the plate-to-body surface and the air filter to the housing surface. The holes for the breather pipes are tapped to accept a new threaded breather pipe, and new pipes are made.

After all the machine work has been completed, the housings are cleaned again to remove any debris from the machining process. New lead plugs are installed into the carburetor bodies, and the passageways are pressurized to check for leaks.

Carburetor Coating after Repair

Most of the early carburetors made by Weber did not have any finish applied to the outside of the housings. This leaves the housing susceptible to the elements. The Weber 40 IDTP was delivered with a green Alodine, or Chemfilm coating, applied. This coating was designed to protect the cast aluminum body from corrosion. Today with the EPA laws and many states going after plate and anodizing shops, it is hard to find a shop to re-create this finish. More often, the shops that are still applying these coatings only want to deal with new parts.

There are also limitations regarding how much protection a Cemfilm finish adds to the cast aluminum. In the last few years, we have taken to applying a Cerakote finish to all the carburetor bodies that we do. To keep with the original look, carburetors built between 1966 through 1968 have a clear finish applied. For carburetor bodies from 1969 and on, we apply a green finish.

The baked Ceramic coating provides superior corrosion resistance while maintaining the original look. Although we want the finished product to look good, we also want it to last another 50-plus years.

Carburetor Reassembly and Testing

With the machining and coating process completed, carburetors are reassembled on the bench. New and reconditioned parts are installed. When it comes to the brass components, more often, almost all are replaced at re-assembly. New throttle shaft bushings are installed and sized to fit the shaft. Throttle plates are always replaced as they tend to always wear out. The carburetor’s calibration package is installed and matched to its intended use.

After all the bench settings have been completed, the carburetors are moved to our test engine. Carburetors are installed onto an actual Porsche 2.0L engine. The engine is then started, and the carburetors are tuned. This process allows us to confirm the functionality of the restored set while also making it easier for the end user. Once the run test has been completed, the carburetors are removed and drained of all fuel. Then packaged in sealed plastic bags for transport.

What Parts and Calibration Package was Installed in this Set

Calibration Package Installed

Main Jet	Air corrector	Emulsion Tube	Choke Size	Idle Jet	Accelerator Pump Discharge Volume
125	180	F26	30 mm	.50	.50 cc

List of new Parts installed into this set

Image Gallery

Terms of Sale “SOLD”

This set of Carburetors is offered at $8000.00. This includes Ground shipping within the USA, base gaskets, and velocity stack gaskets. We will ship worldwide, but please email us at contact@klassikats.com for a shipping quote before purchasing. The carburetor set comes with a 12-month warranty against defects in workmanship or materials. For more information or if you have questions, please feel free to email us or call us at 928-910-4423. These Carburetors have been Sold.

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