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Discussion Starter · #1 ·
It failed the 15 and 25 mph test on the Dyno machine. Max HC (ppm) @ 15 mph is 122 and it measured 292 at 15 mph.

At 25mph Max Hc (ppm) is 95 but it measured 224. Does this mean it is burning too rich? Possibly, closed loop? Would leaning out the mixture screw help with this area?

I replaced all the smog componets: new smog pump, a rebuilt carbureator, new oxygen sensor, new air diverter valve that directs outside air either into the exhuast manifolds or to the intake, and new smog pipes and check valves to each manifolds. A new distributor, fresh spark plugs, and correct timing.

The pub calls for 15 Degrees btdc timing and 25-30 degrees of dwell, and .080 of spark plug gap. at 1100 rpm's all with the computer and vacuum hoses disconnected and plugged at the carbureator.

This is a rebuilt engine with 75,000 miles and a rebulit 3 speed tranny.

Any ideas?
I also have a bluish color to my exhaust after driving on the highway, and is just idling at the stop light. But is not noticeable with light acceleration.
I have the HEI distributor with the electronic advance, and the 4 barrel rochetster carb with the two electronic fuel metering sensors. I dont know if this is a california car, but I do have a vaccuum pump that is pulley driven, for which I cannot find any tubing schematics, and I currently have hooked up to a metal vaccuum line going to the back of the carb and to the brake booster.

I also noticed that the air diverter valve will not divert air to the exhaust manifold at all, during all of the engine operation modes, But will send air to the cat if I disconnect the vaccuum line to the diverter valve, The valve has a vaccuum line and a electrical connector. The diverter valve gets its air from the air control valve which also shares the same vaccuum line from the passengers right side of the carb and it too has a electrical connection. The air control valve bolts directly to the smog pump and diverts air to the diverter valve or to the intake plenum. it only puts out to the plenum
Is the air diverter valve supposed to push air into the exhaust manifolds and the cat, or is hot air supposed to come out of the manifolds through the smog tubes past the check tubes into the air diverter valve to the air control valve and into the intake plenum? My understanding is that the smog pump pushes air into either the exhaust manifolds or the cat depending on the warm up sequence of the engine, in order to complete the combustion in the cat of any unburnt fuel vapors from the combustion process in the engine. Thus reducing the smog out the tailpipe. Is this correct?
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