ShopTalk Forums | Aircooled VW Tech & Restoration Help

hey fellow dirt lovers . I was hoping to get a little info on jetting some carbs i just purchased . they are dual zenith 32ndix carbs. i will be instaling them on my Baja Bug . 1600dp ,pertronix ign, 009 dist bosch blue coil & tri-mill exh. im not to sure if this is all the info needed, um, the rest of the engine is stock. any info would be greatly appreciated thanx shawn

I would just stick with whats in them and try it when everything is adjusted correctly. If youve got a flat spot it might be the 009 and if youve got headers that might change things a little.

Take a few plug readings as every motor will be jetted different. If the carb is jetted even close you will have no flat spot with the 009. Zeniths 32 NDIX are not fussy about jetting as they will run pretty good if the jetting is even close. I would suggest runing a single instead of the duals. Vic. "Parts Book" Schematics and VW part numbers. -> http://www.vwhelp.com
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just wondering why do you think i should run only the one zenith? reason being i bought them both comp with manifolds, Gene Berg linkage and all the fuel lines . if this is not going to work on my application then im going to have to find a manifold to fit. thanks for your input -Vic. shawn

Because it better to run a single centermount carb offroad. Less adjustments, less sloshing of fuel in the centermount, no linkage to sync.... and so on.

That is an old wives tale! A single is simpler in concept but is actually harder to get dialed in. Problems to over come abound, fuel seperation, heat etc. Plus you get more power with duals. Zeniths are old, old school but they do work. Not as well as Webbers but they do work. If ya got'em use 'um!

Are you saying its easier to dial in duals than a single??

GDRBO is correct, it is normally easer to tune Duals then a Single.
I suggest the single because 2-32NDIX carbs are a little to large for Low end torque. Remember that a given size motor requires only a certain amount of air at a given RPM. With Duals the same amount of air is divided by 2. The carb knows what to do by sensing the air flow through the ventures. With the duals, so little air will be passing through the ventures at low RPM, the carb will have no idea what to do. Jetting will be very difficultly. Since You have the dual set up already, why not give them a try, but if they don't work or if they are dead off the bottom end, don't blame it on the 009. Let us know how it comes out. When you get done tuning them, you will be the expert. Vic. "Parts Book" Schematics and VW part numbers. -> http://www.vwhelp.com

I'm surprised that none of these experts have given you the physics of how to jet carburetors (maybe they don't want to share, or perhaps they're not experts). Your Zenith's are 32mm, that is the size of the bores. Determine the choke (venturi sizes) which should be stamped on the side of the carbs. Multiply the size of the venturi times 5 (say 28 X 5 = 140) Start with a 140 main jet. Now add 60 to the number you obtain in your first calculation to determine the air corrector size (140 + 60 = 200) start with a 200 air corrector jet - it is that simple. Remember this is a starting point. If your car is crisp when cold and sluggish when hot you are too rich. If you are sluggish when cold and it runs better when hot you are too lean. Good luck. The real advantage of using multiple carbs over a single carb is throttle response. Your carbs are closer to the heads and you are feeding one cylinder per barrel - it takes less time for the fuel to reach the combustion chamber after you crack the throttle.

Call Tom at 818 841 0502 he is The Expert on Zeinth Carbs and Has Aa large selsction of parts for them tell him Steve sent ya

hey guys thanks for all the excellent info.i will post when i get it all put together thnx Shawn