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Post by claythorpe on Jul 11, 2005 12:19:05 GMT -5
I have a '73 gmc 1/2 ton with a 350 motor. I rently put a new oem carb on it but I am not 100% sure on the vacuum line routing. I put them on where they were when i bought the truck but that doesn't mean they are right. I was wondering where the hose from the EGR valve goes to, right now it is going to the little sensor in the aircleaner. Also I was hoping to find a diagram that shows where they all go just to be sure mine is set up correctly
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Post by 19_Chevelle_69 on Jul 12, 2005 23:42:42 GMT -5
There should be a diagram on the white emissions label under the hood. I can tell you for sure that the EGR valve does NOT get hooked up to the thermal switch in the air cleaner, thats to control the door for the heated air tube from the manifold.
The EGR valve should be hooked up to a ported vac source....one that has vacuum when you open the throttle, but not at idle.
The distributor advance gets hooked up to manifold vacuum, where is has vac at an idle, so does the tranny modulator valve tube (if you have an automatic trans).
Emissions control stuff changed from year to year, model to model, and even changed more than once in the same year. It's nearly impossible to give you an exact routing, there are probably close to 30 different systems used in these years.
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Post by claythorpe on Jul 16, 2005 21:01:53 GMT -5
I have one hose from the thermal sensor in the air cleaner to the little door thing in the neck of the air cleaner and the other hose goes to the egr, so where should that go instead and the egr should be to a port on my carb ? I do have a couple ports on my carb that are just plugged. I looked and there is no label in my truck showing me.
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Post by 19_Chevelle_69 on Jul 17, 2005 9:06:08 GMT -5
The hose should run from the flapper door, to the sensor in the air cleaner, then from there to a port on the thermal vacuum switch on the thermostat housing. This basically makes the door work only when the engine is cold. You can eliminate this system if you like, without too much trouble.
The EGR valve hose should run from the valve to a ported vac source on the carb. This port on the carb will not have vac at an idle, but you'll be able to feel it pull when you snap the throttle open.
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