Emissions Partially Hooked Back Up

[Kilgore]

Been on a little journey to get some emissions hooked back up. Finally got a gas filter and the computer. I'm hoping now that these will take care of the excess tank pressure that seems to be building up in the gas tank. The computer is necessary to get the VSV to open up according to speed/throttle. Whenever I stop driving after a longer drive, I can hear a whistling noise coming from the tank. I hooked up the gas filter to number 3 on the VSV. Normally this would be routed to a union that takes the PCV and has a little side spout for this. I saw that there is room for more, to take connection 8 which would normally route to the vacuum surge tank>air bypass valve. This seems like the most common way people hook the charcoal canister back up.

 

[Pighead]

Whenever I stop driving after a longer drive, I can hear a whistling noise coming from the tank.

Mine does that too, has been for years. Sometimes, just sitting in the sun will make it whistle. There's a rubber pressure-relief type flapper in the fuel cap that makes the whistle I think. I like the idea of some pressure in the fuel tank, might make the fuel pump's life easier.
I don't know if I would trust that VSV and computer to do anything right unless I rebuilt them. There's a good discussion about charcoal canisters; Prototyping a Serviceable Charcoal Canister for the 40-Series - https://forum.ih8mud.com/threads/prototyping-a-serviceable-charcoal-canister-for-the-40-series.1380259/

 

[Kilgore]

True, there was a guy on the forum who was taking apart the computer and testing them. Its phase one where I am assembling all the parts and running them. Eventually I want to go back to the 76 carb. What I have read is that these 2Fs run best on the factory carb and in fact the 76 carb has the most CFM of any carb. I have the man a fre cam and headers.

 

[Pighead]

True, there was a guy on the forum who was taking apart the computer and testing them.

That might be @Engineer8000 . There are probably testing procedures for that VSV and computer in the emissions manual. I did not care for those parts and removed them. My charcoal canister vents to air in the engine bay. I get no gas smell so I guess it works. Coulda run the outlet hose to the air cleaner or something but fewer hoses is better for me.
I hear that the Aisin carb works best on these engines, I've never run anything but the original carb so have nothing to compare it to. The '76 carb may flow more air, but it has the vacuum secondary and other complications. I prefer the manual secondary and simplicity of the '74 carb. I did not care for the fuel cut-off solenoid or the vacuum-operated throttle positioner so I removed them too. I don't think I could have done that on the '76 carb. I got a cam and headers too

 

[Engineer8000]

Yes, I test/repair the emissions computers. I don't mess with the VSVs because there is really no repairing them unless you find a working unit and cannibalize. Many of the VSVs I have tested have at lease one bad valve.