Petcock question

[David Fallon]

Hi all;

My KZ fuel petcock seems to have a one way valve built into the vacuum 
side of the metal plate.  I have it disassembled, and when I pull a 
vacuum through the metal tube that the engine vacuum connects too, it 
flows great.  When I try to blow through that same tube, it is no flow. 
  I see this is why the fuel never shuts off.  Is there supposed to be a 
small restriction to help even out the flow?

Thanks

David Fallon
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