The flat accelerator pump was not used on the 346s. My guess would be either someone inadvertantly (or otherwise) switched a tag; or someone "married" the bowl cover and pump from a later carb to the 346s.

Jon.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop