Idle Issues/EGR valve

[elwhitey]

I celebrated PHX's new found rain a couple of weeks back and now my '74 Jimmy has been wanting to stall once it gets out of the garage. I have tightened down the carb, changed the PCV, air filter, plug wires, and have now gotten to the EGR valve. I have not been able to find any diagrams showing where the vaccum line goes to on it. Does it just hang out? My experience tells me no but I am not seeing anything to indicate otherwise. I gootta trip to Mexico hinging on this.

 

[detailer03]

The vac. line from the EGR does go some where. I believe it goes to the intake or carb. You have a vac leak, that is why it stalls.

One way to find it, go get a can of carb cleaner and spray it around the base of the carb, etc. The rpms will change. That is where the vac leak is.

 

[1985_K5_Silverado]

Look at the around the base of the carb for a vacuum hose fitting that doesn't have a hose on it (which would be a gargantuan vacuum leak); this is likely where the EGR valve's vac hose hooks up. I'm trying to think if a '74 would have one of those little diagrams underhood, showing where all the vacuum lines go.

 

[diesel4me]

early or later 350?

The older 350's had the EGR valve vacuum hose connected to a ported vacuum switch located in the thermostat outlet,so it wont activate the EGR valve until the engine is warmed up..the vacuum source for this switch usually came from a port on the carb itself, some had letters cast into the carb near the port to identify the various things they connected to ( A,B,C,D,etc..)..I think the EGR used the "D" port,or it may even have "EGR" on it..its a ported vacuum source,not manifold vaccuum..