1967 K19 Mixture Control Valve / Diverter Valve Diagnostics

[Tim S.]

Do any of you have a "flow chart" if you will for the aforementioned A.I.R. piece? I am working on a new to me L79 / K19 car, and want to make sure all is correct. In short, is there way to test the part? (i.e. vacuum pump, pressure test, etc.)

In advance thank you,
Tim

[Peter M.]

Tim,
There is a technical service bulletin for diagnosing the air injector reactor system, a copy can be found in the back of the 67 technical information and judging guide. (page 305-311 of the 7th revision)
It is pretty straitforward, my mixture control valve was toast.
Kind regards

[Douglas L.]

Hey Tim - to test the pump, start the car and cover the end of the hose that goes from the air cleaner to the pump. It you feel a suction of air at the end of the hose, the pump is working. To test the mixture control valve(motor turned off), hook a small piece of hose to the incoming supply side of the valve and blow on the hose. If you can blow air thru the valve, the valve is most likely not working. If you cannot blow air through it, hook a Mighty Vac to the vacuum hose hookup on the valve. Then, blow into the the incoming air supply hose to the valve and sqeeze the the Mighty Vac handle. The Mighty Vac should create a vacuum and open the valve and release air through the valve. You should hear a short "hiss" of rushing air. The valve will close again once the vacuum pulse created has ended. This process duplicates the way the carb creates a vacuum when you let off the accelerator after revving the motor. Many times, the rpm of the motor will hang up for a couple of seconds and be slow returning to regular idle due to the "shot" of air into the base of the carb leaning out the fuel mixture. If the idle does hang up like this, the mixture control valve is working.

[Tim S.]

Thank you Peter and Douglass for your input. It seems as though according to the flow chart included in the judging manual, I have a mixture control valve that is on the way out. Also, I have an AIR tube check valve that is leaking. I spoke with Bill Hodel yesterday, and he has NOS example of both check valves, along with the mixture control valve (and priced fairly I might add). Bill also confirmed how the mixture control valve was to be tested. Those items are on the way. Douglass, the air pump seems to be very strong.

I'll follow up with an update

[Tim S.]

The popping I had from the exhaust was reduced considerably with the replacement check valves, mixture control valve, and fresh plug wires. Finding a happy place with the timing pretty much eliminated it.