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1972 Chevrolet 454 Failed Smog Test High RPM Portion

I've got a 1972 Chevrolet 4x4 3/4 ton w/454 w/roller rockers, titanium push rods, over sized camshaft and pistons, and a Carter AFB competition series carburetor.

If failed the smog test during the high idle portion of the BAR 2-Speed smog check process. The CO emissions were very high. Prior to the smog test I had added 2 bottles of STP gas treatment to a full tank of gas (approx. 20 gals). Was it too much?

Answer:

We do not believe the use of fuel additives caused your vehicle's high CO fault, and subsequent smog test failure. We recommend contacting the engine performance shop who made your engine's modifications. Engine compression, ignition timing, and carburetor adjustments might have to be made in order to ensure the engine is burning fuel as efficiently as possible. posted by SmogTips Support

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