Two-versions of Weber 40 IDA 3C Carburetor Delivery Valves?

[Auto*Legends]

Each Weber 40 IDA 3C carburetor has three Delivery Valves: Weber part number 64290.005, item 71 in the Weber exploded view drawing. It’s the brass check valve that holds the Pump Jet item 71 (squirter) in place.

I recently removed both carbs for rebuild, but decided to do them one at a time. I disassembled the first carb and subsequently soaked and cleaned everything. I was checking parts for assembly when I noticed that one of the Delivery Valves didn’t have the little check ball inside it. I discussed the finding with a few friends, and consulted with some experts. It was easy to conclude that the part must have been defective, so I ordered a few new ones from the Oil Analysis Company. The Oil Analysis Company is a retailer/distributor of PMO Weber stuff. BTW, I have had great success when dealing with both of these companies.
Anyway, I then decided to disassemble the second carb prior to assembly of the first one and guess what? The center Delivery Valve didn’t have the check ball either. Maybe everyone already knows this, but I have looked and can’t find it documented anywhere.

Thoughts? Comments?

Note, I have also started this thread on the Pelican Technical Forum but thought it might be more appropriate on this forum.

[edmayo]

The end requirement here is that all three nozzles spray fuel when the pump diaphragm is compressed. My guess is that this was someone's fix for something, who knows. You'll need to measure the pump discharge quantity and adjust for the lower end of the tolerance, memory says .4cc's per two squirts,,,but check me on this.