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Old 03-03-2024, 01:56 PM   #6
willem445
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Re: Vacuum / Emissions Question

I thought I understood what was going on with my diagram more than I did, I'm still a little confused. Hoping for some clarification.

It's apparent to me that someone modified the vacuum / emissions stuff on this truck. Below is the current state of the vacuum lines:


Here is a picture of my engine with things labeled:


Here are a couple diagrams I found online (unfortunately my truck did not have a diagram anywhere)







From what I can tell, there is no EGR valve or EFE valve. I don't see an EGR block of plate so I feel like this truck didn't have one. So I'm not sure if those two TVS's are actually EFE & EGR but I labeled them as such anyways.

I'm planning on replacing the stock air cleaner with an open air cleaner, thus removing all of the air cleaner related vacuum. This is what I had in mind after deleting things:



Couple questions based on that:

1. It's unclear based on the diagram I can find whether the vacuum advance port from the carb should go through a delay valve & EGR to the distributor, or if if should go directly from carb to distributor. Is going directly to distributor fine?
2. Based on my modified schematic, is the EGR TVS doing anything? It seems since it's not connected to anything that actually supplies vacuum, it's just doing nothing. Is that right? Should I delete that circuit completely? What would the rear choke diaphragm connect to?
3. I'm planning on deleting the EFE TVS circuit altogether. See any problems with that?
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1980 Chevy K20 Farm Truck
1977 Chevy K20
1986 Chevy K30 3+3 Dually
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