Unidentified part question

[Whaledriver]

I have only had my 1973 2002 a little over a month. As I get familiar with what has to be corrected and detailed, there are a few items I can't  identify as to their purpose. The car has obviously been de-smogged and being registered as an historical vehicle, it is not required to have the smog devices. Here are a couple of  pics of items that I don't have a clue  as to their purpose. The first pic is on the firewall and has two wires connected at the base but the two ports for a hose are absent of a hose.  The second pic  is below and in front of the carb and being fed by the fuel pump. Viewing other models, I don't see similar routing or device.  Appreciate  any advice.

[worzella]

Desmogged methinks but not declutterred. The first is part of a handful of vacuum switches used in the smog design. Can't recall the web site with the nice picture but search the FAQ for smog diagram and you should see all of these

 

The second I believe is a fuel return check valve also part of the smog setup. I believe one of the three lines runs back to your gas tank. My 75 had this removed with fuel line running straight to carb and gas tank intake stubbed off

[Mike Self]

Yep, Worzella has it correct.  If your smog stuff has already "disappeared" you can remove that vacuum switch with no problem.  And at least on '73s, the entire wiring harness that serves all those emission pieces is completely separate from the car's main wiring harness, so you can unplug it without disturbing the rest of the wiring.  Just make sure you (1) cap any vacuum line nipple that leads into your intake manifold, and (2) don't leave an exposed, dangling hot wire anywhere.

 

cheers

mike

[Mark92131]

4 hours ago, worzella said:

Can't recall the web site with the nice picture but search the FAQ for smog diagram and you should see all of these

 

 

Here's the smog diagram link...

 

http://www.dagsites.com/emissions.htm

 

Mark92131

[Buckeye]

Second picture, fuel return valve. it is not part of somg setup. Keep it.

[FunkyLaneO]

Keep the fuel return valve, ditch the vacuum solenoids. Attach a vacuum line from the base of the carb to the fuel return valve, or tee off the one going to the distributor if you have one.

[Whaledriver]

Thanks to all for the clarification. I'll get rid of the vacuum solenoid on the firewall  and keep the fuel return valve.  Why should I attach a vacuum line from the base of the carb to the fuel return valve as FunkyLane  suggests?

[worzella]

I an guessing (all these other guys are way more experienced than I :)) that without the vac line, the valve won't operate. And as I recall, the point of the valve is such that under certain driving conditions you want to reduce the flow of fuel to the carb and this valve switches over and sends the gas back to the tank instead of pouring it into the carb. 

 

If I made that up, it still sounds pretty good huh  Ha ha 

[jimk]

Leave the vacuum line to the valve alone.  People are making suggestions without knowing how the valve functions or what it's purpose is.  To learn how the valve operates, take one in hand and apply vacuum to the sensing port while applying pressure to the fuel supply line port.

The valve does NOT modulate, it is either OPEN or CLOSED.  Connecting the sensing line to the same line as the distr vacuum advance is wrong and will only bleed off the fuel  pressure (engine running or not) when the throttle is past the economy mode and no vacuum is available at the carb port.

This subject comes up every time someone wants to start stripping stuff from under the hood and don't know what they have their hands on.

The valve sole purpose is to bleed off fuel pressure by venting the fuel supply line to the tank when the engine is shut down and avoid the after shutdown carb boil over.