Sunday, December 21, 2008
Early electromagnetic cutoff valves
That's right, I said early electromagnetic cutoff valves. Jason Weigel recently identified a stash of these valves (the large round device at the right in the photo above) that were used on the VW 1500's Solex 32 PHN carburetor in the first few months of production. They are among the rarest of early engine parts for a 1500.
The 1500 seems to have been the first VW model to come standard with an electromagnetic cutoff valve (a.k.a. pilot jet) fitted to the carb. The 32 PHN carb had one from the beginning of production in 1961. VW buses first got a cutoff valve on the 28 PICT in 1963, and the Type 1 followed suit in 1966 with the introduction of the 30 PICT-1 carb. Since they were first seen on the VW 1500, what's unusual is that this particular valve has a Type 1 part number: 111 129 413. It's possible that it was first made available for VW models other than the 1500 as a dealer retrofit to address problems with post ignition, or it may have had a use on industrial engines.
The design of the valve went through a number of revisions in the first few years of production, and this large diameter version of the valve is very rare. It's unclear from VW's documentation exactly when this design was discontinued. The November 1961 edition of the VW 1500 owner's manual shows this valve, but the August 1961 VW 1500 Workshop Manual shows both this one and a more commonly seen cylindrical version with a small black plastic cap. While similar in function, the large round valve had the added advantage (or disadvantage) of having a convenient on-off switch. For whatever reason, by the end of the 1962 model year the cylindrical version had become the standard (as seen here in VW's Look Listen Do it Better training guide for the 32 PHN carb from August 1962).
Both of these early versions of the valve could be partially disassembled. Later iterations could not be.
There seems to be no clear record of exactly when the large round valve was originally used, but it would be a nice addition to any 1962 VW 1500 engine restoration, especially for cars built in the last few months of 1961. As you can see here, Jason's early 32 PHN carb has all the 1961 bells and whistles.
[Update: Looking in VW Progressive Refinements I found that the electromagnetic cutoff valve was first made available as a service part in July 1957. It was first featured as a standard part on the VW 1500 on its introduction in 1961, and Type 2 models got the valve with the optional 1500 engine (M 216) beginning in January 1963.]
[Photos from Jason, The Samba, and my literature collection]