GlenSwanson@dk-online.dk (Glen Swanson)  wrote:

The 25bhp (30 DIN) @ 3,300

Solex 26VFJ, until 1948
HUF, to 1950
Solex 26 VFIS, until 1952
Solex PCI, post '52.
Single tailpipe.
Bore and stroke 75mm X64mm (1131)
Compression ratio 5.8:1
Mushroon-shaped air filter until 1949 there after the T-Shaped Filter.
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only the earlier 25  hp bugs used a single tip muffler (and buses of course)
air filters are a mess to figure out, as there were so many used.  My 53
microbus came to me with its original air filter, a strap top one, as shown
in the owners manual.   The best way to figure all the dates out is to get a
complete set of owners manuals, shop manuals, parts list, and book of
progressive changes, all put out by vw at the time.  

btw, I would really love a parts list for 29- parts numbers, the earlier
number system that was changed to the current one sometime in 54.  Also a key
book, showing all the key codes nd combinations.  Any leads?

also-  25hp motors came with a 130 watt generator.  These came with a black
band to protect the gen brushes, like early porcshes.   The voltage regulator
is D shaped. In 54 they switched to 36hp motor, 160 watt generator, with a
round regulator.

any 25hp motor found today will likely not have all the original dressings.
  And the early bits may be in boxes or on later motors.  I found a 130 watt
generator on a engine that came out of a 56 beetle.  (later installation)  

happy hunting for all the bits.