Follow this procedure before you bolt any VW carburetor onto your engine, whether they are new or used! It will put you in the position to be able to tune your carbs without other factors getting in the way and creating a fuel system troubleshooting nightmare. If you haven’t set up your carbs yourself, you NEED to. Most people don’t realize that carbs as they are supplied from the factory are assembled, but NOT set up.
The Weber 48 IDA has been used for decades by VW enthusiasts whose goal it is to squeeze every ounce of performance out of their engine. Problem is, production of these coveted Webers was halted many years ago. These excellent VW carburetors in decent condition have become rather scarce! Typically VW performance engine fanatics have to resort to scrounging the swap meets to find a pair of 48′s and even then, they may not be lucky enough to find a pair but have to acquire them one at a time. But if you are lucky enough to acquire a set in usable condition, and you are willing put the time, money and energy into rebuilding and tuning them, you WILL be rewarded. The Weber IDA’s sheer size will likely result in gasps of awe and astonishment from those that have never seen them before!
Aircooled Volkswagen enthusiasts have quite a few carburetor options. Performance increases that can be gained by going with aftermarket carburetion are a common consideration, but without a little guidance, you can end up with nightmares associated with poor carburetor selection or poor tuning. In the aircooled VW hobby world, it is easy to get confused by the volume of available, and often times conflicting information. There are a number of aspects to consider when upgrading your fuel system and selecting the best set of VW carburetors for your engine and driving needs.
After springing for a set of carburetors, some people bolt them on, and are “pleased” with the results. Others are upset by a backfiring, or smoke belching monster. In either case, spending the time to properly jet a set of dual (or single) carburetors is a worthwhile task, since receiving “perfect out-of-the-box” carburetors is one of the biggest myths in the VW industry!
Proper jetting varies depending on engine size, elevation, cam overlap, etc. Jetting is so specific to an individual engine that two identical engine combos with the SAME carbs can even require different jets! The moral of the story is: With your engine combo, carb information and driving elevation, we can advise and get you CLOSE, but to know that your carbs are jetted optimally, you will need to spend the time necessary to dial it in. It IS worth doing for drivability, engine life, and mpg
This article contains the step by step, detailed procedure for synchronizing dual carburetors on an aircooled VW engine. But before you actually tackle the syncronization, remove the air cleaners, and make sure there are no vacuum leaks (spray starting fluid around the carburetor bases and intake manifolds while the engine is idling). Make sure the engine’s ignition timing, valve adjustments, and other items are all correct also. You do this to ensure that you are adjusting the carburetors to a TUNED engine, not one that has problems.
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