This is the Secondary (large, 36mm OD) throttle plate for Weber DGV-series carburetors. The Secondary throttle shaft is driven by the primary throttle shaft (the primary is the one that the throttle cable pulls on).
The DGV family of progressive carburetors use a smaller primary throttle coupled indirectly to a larger secondary throttle. This arrangement produced good idle, off-idle, and part-throttle characteristics by running exclusively on the smaller primary throttle. The larger secondary only begins to open when the primary throttle is more than about 50% open.
Fits the secondary throttle shaft of Weber 32/36 DGV, DGAV, DGEV, DFV, DFAV, and DFEV carburetors. Does not fit 38 DGAS/DGES.
