is one brand superior to the other ?

Jim

I don't know if Webers are superiour to Solex
But from what I understood...
Webers have the advantage of having lost of choices for venturis, jets, etc. which you can get seperately to set them up to your specific needs
And you can access all these parts easier with the carbs in the car
That is why they are more popular

Solexes are basically meant to be OEM carbs, so there are few tuning parts available for them. Parts period are getting hard to find in the US. Solex was bought some time ago (by Mikuni, I think). Weber is the grand-daddy, and made OEM and aftermarket carbs, so there are lots of tuning parts available. Dell Orto is roughly similar to Weber, though tuning parts are getting harder to source, as Dell Ortos have been out of production for quite some time.

In terms of performance, like for like, the Solex PII-40 and the 40IDF are pretty close. The Solex is VERY sensitive to float height, where the Weber is more forgiving in this respect.

The point is somewhat moot if you're in the market for carbs. You'll find 100 sets of used IDFs for every set of used Solex PII-40s out there, unless you happen to know a lot of 356/912 people, since the Solex came OEM on those engines (well, SOME of the 356s). IDF parts can also be picked up at nearly any Bug shop, where Solex parts can only be sourced from one or two shops online.

I have the dual weber idf 40, so Weber is better....

If a Weber is 40MM at the butterfly it is less at the top. The Solex is 40MM at the butterfly and larger than that at the top. = better flow at high RPM as in racing. Be careful ! the early Solex had a split shaft connected between the bores. The later ones had a solid shaft...better.

Actually, Al, you have that reversed. The early Solexes used a solid shaft, and the only way to correct imbalanced airflow through each throat was to bend the shaft. The later carbs had a split shaft with a screw adjuster, so you can balance them on the car by just twiddling a screwdriver. That said, the adjustment mechanism on the split shaft carbs tended to break after 10-20 years, which was never a problem with the solid shaft models. However, by that time, you usually needed to rebush the throttle shaft holes in the carb bodies, anyway, which means removing the shafts.

The split shaft carbs didn't appear until the 912 was out. 1968, I think.

Oh, and both Solexes and Webers are smaller above the throttle plate, as that's where the venturi is, which is by definition smaller than the throttle. The Webers have easily replacable venturis in many sizes, up to about 36mm for a 40mm IDF. The Solex PII-40s that the 912 used had a 32mm venturi, which was pretty big for a 1600. The Type IV 1.7 usually uses a 28mm venturi, where the 2.0 uses a 32mm venturi.

I just love acquiring these tidbits of knowledge. Great info, truely. Thanks James.