Vent Solenoid

[Brown_Muscle]

Hey all, does anyone know if the vent solenoid(S) come on with key on/engine running. Or if my MCU controls it? Going to being to get rid of my smog shit and I want to know what to do with them...I do have the connection on the new carb for the vent.

[86VickyLX]

mcu controls that.

[Brown_Muscle]

So should I just disconnect the solenoids and have it running all the time? How do the uncomputerized carb'd cars control it?

[Brown_Muscle]

Anyone know how early Carb systems controlled the charcoal canister without a computer? Can i do it with my car? I dont want fuel leaking out and my car setting on fire

[P72Crazy]

On the 2150 motorcraft carb there is a lever on the accelerator pump that keeps the vent valve open (in the air horn) to the charcoal canister when the engine is off. The valve closes when the engine is operating. This system is all about the fuel bowl boiling fuel vapor out and causing issues with drivability and engine performance. Also you can think about it as a vented system. The later model applications are more about collecting fuel off the fuel tank (closed system). You indicated you had a hybrid or Frankenstein application. The 2150 also had a high speed air bleed metering yoke and lift rod. If you have a different air horn than "lower", you could be missing some important functions designed into the 2150 that were not in the 2100. I have a good old book, "How to Tune Your Car" 4th edition (Petersen's). This old book goes through these old carbs in fair detail.

[P72Crazy]

Does your air horn have the bowl tube? This tube feeds two small nozzles in the air horn which enriches the mixture at higher RPM. I'll try to take a picture of mine in the basement.

[Brown_Muscle]

Interesting, I have the bowl tube, the horn and bottom end are original to that carb, so those arn't mixed up. Neither of my 2150's have that extra lever on the accelerator pump though, i think i have the later "closed system. after doing some reading and looking at parts it looks like i need 3 things. correct me if i'm wrong here.

1) A VCV vacuum control valve that opens the passageway to the bowl.
2) a 1 way valve that run in between the bowl and that valve
3)A Vacuum purge valve that opens up the engine vacuum into the system to suck in any vapors from the canister

And of course all the hoses to go with it. This seems to be how the early systems functioned.
The Purge valve is linked to a temperature regulated vacuum switch (i have 2 now i can use from the old VV system) This would allow it to open when the engine was heated up and reached a certain RPM
The other allowed the vent bowl to open into the system, but not feedback into it (1 way valve) sucking any vapors off of it as the engine was running.

[P72Crazy]

Honestly, it all sounds reasonable but I'd concentrate on getting the vapor canister purged and not worry about the fuel bowl. How much vacuum and when to apply it to the carb bowl seems sketchy to me. I think Ford and the EPA opened up a can of worms with all those carb mods. I can remember a 66 Galaxie with a 289 that had a lever and paddle arrangement that opened a tiny hole in the top of the air horn to vent the fuel bowl (yes vented to atmosphere). What little fumes/vapor comes off the carb would be tiny compared to what comes off a full tank of fuel on a hot day! If the fuel level in the bowl is being tightly controlled by the needle and seat I see no need to open it up to the atmosphere or vacuum sources. I'd be more afraid of getting fuel vapor in my other vacuum controlled devices than having a tiny "fart" escaping to the under hood airflow.

[GM_Guy]

On my Generals, the charcol canister vent is Tee'd into the PCV valve line.

Alex.

[Brown_Muscle]

Oh yes it will be purged, my intake has a nipple just for this and that's what I'll be hooking it in to. It's right next the PCV port on the intake (yeah not on the carb, although i have one of those now). I'm not too worried about the bowl, but since I see how it works in earlier model I'm going to go for it.

I'm worried about what temp and RPM's are simply because if it's open at idle, it could bog, and possibly stall if it gets too rich, same with temp, def want to make it warm up first so the chokes off all the way. It's a fairly simple system, and even if it isn't exactly how ford engineered it, it's close.

If it interferes with drivability, then I'll go a different route.