Smog pump rebuild on 1969 L35

[hihorse]

Looking to put the smog back on my 396 engine. Has anyone rebuilt these smog pumps? Read in a thread  about de-vaning them so they do not pump air, is this something that has to be done professionally?

[PURESS]

http://www.z28camaro.com/       Jerry has smog pumps or could rebuild for you

[Stingr69]

Rebuilding must be done by a pro.

De-vaning a pump can be done by anyone with a socket wrench to pull the back off and a screwdriver to break the vanes. They are a carbon-like material and snap rather easily. The pump will be trashed but it will not pump air anymore.

I don't trash the pump vanes.  I just put holes in the underside of the rubber hoses that go to the check valves (screwed on to the trees). Nobody sees the holes and rubber hoses are very cheap & easy to replace, unlike the pump vanes. I remove the extension tubes from inside the manifolds and insert the screws (points up) to block the tree openings and the whole thing looks stock but is non-functional. Just another way to do it. FWIW.

-Mark.

[hihorse]

Thanks for replying. Leaning towards devaning because HP would not be lost to drive the smog pump.

[JohnZ]

The A.I.R. pump absorbs less than 1/10th of a horsepower. What you gain by de-vaning the pump is elimination of the pump failure mode, which is seizure of the vanes to the surface of the pump housing; no vanes, no failure mode.

[hihorse]

HP loss is not much!  Why would the vains sieze against the housing? due to bad bearings?

[JohnZ]

HP loss is not much!  Why would the vains sieze against the housing? due to bad bearings?

The rotor that carries the vanes is off-center in the housing, and the housing is machined as an eccentric (like a power steering pump); the edges of the vanes ride on the surface of the housing and move radially in their slots in the rotor with each revolution, and eventually wear and gall (no lubrication), then they seize and the pump stops.

[Jerry@CHP]

Here is what's posted from our web site, www.z28camaro.com.  We recommend non fuctional for all systems.

Jerry

We can build your NOS smog system either functional or non-functional. There is no extra charge doing it either way. There are several advantages letting us build your system non-functional and we'll explain why:

#1. Gutting the smog pump and building it non-functional is the better way to go because there are no back firing issues when letting off the gas. Any time you let off the gas while driving your car you will experience back firing and popping. This was due to the smog pump and diverter valve pushing air through the system. There are documented cases of this backing firing destroying the exhaust system muffler. When gutting the drum in the pump assembly, your system will run quietly and look like it's functioning fine.

#2. Smog tube plating, as we know, original smog tubes were plated in a black zinc finish. When running a functioning system, the 1200 degree exhaust temperatures exit through the tubes. Within a years time, the heat will take it's toll on the black zinc plating destroying most of the factory finish. If we build the system non-functional, the tubes are plugged not allowing exhaust flow into the tubes preserving the plated finish.

#3. Exhaust flow, by letting us build your system non-functional, the exhaust port tube extensions are not needed. This will allow the exhaust to exit the cylinder head port without flow disruption increasing the horsepower in your engine.

So as you can see, there are several advantages to letting us build your system non-functional. All systems on our own personal cars are non-functional too. And remember, Camaro Hi-Performance is your best choice for that NOS smog system you need for that Z/28, 327, 350, 396 or 454!

[Pex68]

Jerry did mine, non functional, and it looks brand spanking new.  I also got all the gut's back in a little zip-lock baggie.  Highly recommended.