Gas Cap + EEC System

[SeventyOne]

Hey everyone,

I have a question about the EEC system on my K5 and my gas cap.

I think I have everything hooked up correctly:

• PCV hose from carb to PCV valve "T" on valve cover, hose continues to the vapor canister.
• I have a smaller line running from the timed vacuum port on carb to the vapor can
• And the 3rd port/hose on the vapor can goes to the hardline on the frame rail that goes to the gas tank.

All that said I shut off my engine the other day and noticed a sucking/hissing sound coming from the gas cap until what I assume was all the vacuum releasing. I have a locking gas cap unit like this:


Think i got it from Brothers: https://www.brotherstrucks.com/1967-...tinfo/GCP66FL/

Is the sucking sound normal? Do I have the wrong gas cap?