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Discussion Starter · #1 ·
Hello. I'm brand new to the forum so I apologize if I've posted in the wrong thread. I am the proud owner of a 1986 chevy c20 Silverado 3/4 ton long bed with the ever so Eco friendly 454. The truck is carb'd, factory no cats and no computer of any kind. It has two smog pumps, one on top of the motor and one on the bottom left that push air into the manifolds. I really would like to remove these pumps as I'm sure they rob quite a few horses and clutter up the engine. So my question would be will this be a smart removal or would this cause and issue with gas mileage or something worse?
 

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I don't think removing the smog equipment from your truck will cause any issues,
one easy way to tell would be to remove the belt that drives the A.I.R. pump (air injection reactor), forgive me if I'm
wrong but I believe your truck has multiple belts, and I think the A.I.R. pump has it's own that drives it and nothing else.
I am also assuming that the other pump you are talking about is the egr valve which sits on the intake manifold, in
front of the carb I think.
You can remove the vacuum line that supplies the egr valve (it may go directly to the egr or to a solenoid that controls it)
and plug it off at the carb.
This should effectively disable it all, so if you drive around for a few days and don't have any issues I would think you
can go ahead and remove all the crap(as long as you are SURE that you won't have any issues passing inspection).
With this stuff gone you may even see gasp! double digit fuel mileage from your 454( I have a 92 chevy with the 454 and I think I am
the only one at the gas station who is happy to fill up and be in the double digits.

Joe
 

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Discussion Starter · #3 ·
Lol 454 passes everything but a gas station. The top pump runs alone. The lower pump runs along with the alternator. I'm sure I can get a smaller belt to bypass it. And here in Texas my truck is safety only and doesn't go through any emissions testing due to year and no cats. Thanks for the input. I'm definitely going to try it. Double digits sounds amazing. Even if it's only ten mpg haha
 

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That's weird,
I have never seen one of these trucks with two smog pumps.

I wonder why heck there is two?

Joe
 

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Discussion Starter · #5 ·
It is pretty weird I'll post some pics when I get home
 

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Discussion Starter · #6 ·
Gold C20 said:
It is pretty weird I'll post some pics when I get home
And also I'm no mechanic the other pump could serve another purpose and I am mistaken.
 

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image.jpg
image.jpg
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image.jpg
 

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Thanks for the pics,
I searched online and sure enough, I found other owners of 86 454s talking about having two smog
pumps.
I don't know if 86 was the only year they had two, or just a coincidence but everything I read talked about an '86.
My 92 has only one A.I.R. (smog) pump, I also had a 90 454 and it had only one. Of course these engines both have
throttle body fuel injection, so maybe that made them run a little cleaner and negated the need for two pumps.
I know that, in 87 all the half ton chevy trucks switched two throttle body injection and I think the c20 and c30s two,
so 86 could be the only year that has two pumps.
Jeez, they had a lot of [email protected] under the hood back then.

Joe
 

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You shouldn't have a problem removing them, I removed all the emissions stuff off my 83, 84, and both 79's with out a problem. But I would recommend new headers and an intake. They really help those older engines out, for both power and MPG.
 

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Discussion Starter · #10 ·
Thanks daly and joe. This is the very last year of the carb'd 454. Yes it is a super cluttered engine compartment. I'm envious of the 350's because you can pretty much sit in there. And yes I would swap manifolds ( I got some picked out already). This truck has so many vacuum lines it's crazy. Even if I take the breather off the intake manifold is barely visible due to all the rubber lines. It has a Rochester quadrajet with about 8 vacuum lines that run in and out of it! I'm slowly trying to figure out which ones I don't need anymore. Daly are you suggesting a new intake manifold or air breather?
 
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