1042medic Posted October 2, 2014 Report Share Posted October 2, 2014 There's antifreeze behind it, one of the broken nipples went to the EGR valve, one goes to which eventually ends up in the carbon canister Quote Link to comment
datzenmike Posted October 2, 2014 Report Share Posted October 2, 2014 It's a broken thermo vacuum valve. There is a ported vacuum source on the carb that has vacuum applied only above idle. This vacuum becomes less and less as the throttle is opened to full throttle. The valve is closed until the engine coolant warms up at which point it allows a vacuum signal to the EGR valve and the carbon canister. Exhaust gasses are recirculated only at part throttle (never at idle and not at full throttle) and only when the engine is up to operating temperatures. The vacuum signal to the carbon canister is only that. A signal that tells the canister to open a valve so the saved gas fumes can be drawn into the intake through another hose to be burned. Your engine will run without it but the carbon canister may start to smell of gas fumes. Just keep an eye out for one that is not broken and swap it later. BTW that three bolt thermostat cover was mostly used on the later '79 L20Bs. Possibly your engine may have been swapped. Quote Link to comment
bilzbobaggins Posted October 2, 2014 Report Share Posted October 2, 2014 thermo switch for smog I think Quote Link to comment
1042medic Posted October 2, 2014 Author Report Share Posted October 2, 2014 So my next question...My EGR valve is gone, so where do I send the second nipple/hose that use to go there, do I just cap it? AND Can you guys look at this next pic and tell me if this U-turn this hose is doing legit? The bottom line goes directly to the thermal vac valve (thanks to you guys I know this now) the other one goes to distrib and canister. Quote Link to comment
datzenmike Posted October 2, 2014 Report Share Posted October 2, 2014 There should be two ported vacuum supplies on the carburetor. One supplies vacuum above idle to the distributor vacuum advance to improve part throttle efficiency, mileage and drive ability. The other one is for the EGR as previously described. Someone has joined them but they are not connected and not working anyway. When the carb is put back on I would use that hose to connect up the vacuum advance. You need it. Quote Link to comment
1042medic Posted October 3, 2014 Author Report Share Posted October 3, 2014 Thanks Mike, I appriciate it. Let you know how it goes. Quote Link to comment
datzenmike Posted October 3, 2014 Report Share Posted October 3, 2014 Sorry, of the two vacuum ports on the valve cover side of the carburetor, the one to the front is the distributor vacuum advance. Quote Link to comment
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