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Carb Modifications VW engines are EXCEPTIONALLY under-carbureted. You have many options, all of which require more exhaust flow. First option is the new dual solex 35mm carburetors, with or without chokes. For stockish engines with a worn out stock carb or for someone who just wants a little bit more performance without the headaches of constant carburetor maintenance, these are the carbs to get. Currently they are only available for dual port engines. Single port engines should use these dual-single bbl carbs. This kit has a steel crossbar (not center-pull and NOT aluminum) linkage. Third option is the center mount 2bbl, which can be a SOB to tune, and requires manifold heat. Jetting this sucker can take a while, but if/when you get it right, it's a fantastic setup. It ONLY works on upright engines (type 1 and 2), since type 3 and 4 engines don't have manifold heat, and a center mount carb WILL ice up and be a nightmare to drive! Dual 2bbl carbs. MORE options - Dellorto DRLA's (the IDF counterpart), and the Weber. Weber makes the IDF as their main carb, and the IDA, which is primarily a race carburetor set. You also have the Weber DCNF, and Solex 40P11 (used on old Porsches). IDFs come in 40, 44, and 48mm sizes. Nice carbs for street cars, but the factory making them has closed down so availability is getting scarce. These are also the carburetor of choice for off road cars! Off road cars should run a center mount (instead of duals), either progressive or IDF. IDAs are race carburetors. Contrary to popular opinion, these CAN work very well on the street! Not much of a progression circuit, so in unmodified form, they are either off or on! (Idle or full throttle). Modifications properly done will make them more "driveable", and once modified they work VERY well. Many guys routinely report 8-12 mpg (yikes!) but in these cases they are jetted all wrong. 25-27 mpg on the highway is correct when they are properly set up, even on large engines. However, IDAs do not have provisions for vacuum advance which we feel is a requirement for a true street carburetor. Solex 40P11 are old carbs, rather rare, and work very well IF they aren't worn. Similar to the IDF and DRLA in appearance and function. DCNFs are getting to be very tough to find parts for, and easily flood if the going gets rough. The cost of the air cleaners, linkage and intake manifolds individually for the DCNF can be very expensive, so we recommend that you DON'T buy a set of DCNFs unless you are getting everything with it! Your best bet on dual carbs for the street now are the Dual Weber IDF, in 40, 44, and 48mm sizes. We offer these with a "setup and adjust" option to minimize your headaches, just bolt them on and go! I run either the stock carb, or any of the dual 2bbl carburetors. I see no point in dual 1bbls, so I skip these. Venturi size (the narrowest part in the carb throat) should be about 3mm smaller than intake valve on stock or mild engines, and about SAME size as the intake valve on high output engines. All 2bbl Dellorto and Weber carbs have changeable venturis, so you can match the carburetor to the engine somewhat by tuning and re-sizing - but don't expect a set of 44 Weber's to work on your stock 1600 cc engine!. Remember, venturis and jets are expensive, so it's best to start with your carbs in the right range. Re-jetting a set of dual 2bbls will cost about $100-150. It ain't cheap and it takes HOURS to dial in… |
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