VW Trends - December 1998 - The Weblink
Upgrading Dual IDF Carburetor Linkage
Weblink - Upgrading Dual IDF Carburetor Linkage
Weber carburetors are considered by many to be the finest high performance carburetors available. Webers have been used to fuel just about every type of racing engine imaginable. High-powered race cars, boats, motorcycles and even airplanes have been equipped with Weber carburetors. Weber carburetors have greatly influenced the design and performance of VW racing engines to the point that Weber has become woven into the VW performance vocabulary. You hear the language every time VW owners talk about "Dual Weber Engines, Single IDF's and Dual 44's'. And check out those IDA's!
Unfortunately for those of us involved in VW and Porsche engine tuning, Weber no longer offers IDF carburetors in "right side," and mirror image "left side" sets. Weber manufacturs only right side carburetors. The lack of a matching left side carburetor stands out like a sore thumb during installation on a VW engine because the left side return spring is located on the opposite end of the carburetor shaft when compared to the right side carburetor.
This omission in the Weber product line is obviously driven by pure manufacturing economics, one part number rather than two makes life simple at the factory. But it certainly causes the end user continued difficulty in establishing and maintaining precise carburetor balance. Does it really matter that the return spring on the left side carburetor is on the opposite end of the carburetor main shaft as the spring on the right side carburetor? You bet it does!
The positioning of the return spring on the opposite end of the left side carburetor (away from the driven end) will create uneven tension of the complete throttle linkage system. The continual stress on the left side carburetor shaft will eventually cause the shaft to twist. A further guarantee of a twisted shaft, resulting in misplacement of the throttle plates. And, as you know at this point in the playoffs, exact carburetor balance, or the lack of it, represents the fine line between a crisp-running engine and one that's not exactly running right.
The problem is now quickly put to rest by installing a new linkage arm and return spring on the left side carburetor. The procedure requires removal of the original Weber throttle arm and drilling a small spring location hole in the base of the carburetor. The installation results in a set of matched right side-left side carburetors with equal spring tension and improved throttle action. The parts can be installed on all IDF carburetors that are equipped with a threaded throttle shaft end. Here's how to convert you IDF's to a more manageable rightsid-left side combination.
If it is necessary to remove the carburetor from the vehicle, disconnect all items in order to remove the carburetor, such as throttle linkage and fuel line. This work is going to be done to the left side (driver side) carburetor.