Smog Pump

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Nissan A.I.S. (Air Injection System) with air pump system -- a.k.a. "smog pump" -- was first fitted to some 1960s Datsuns. The first B-series models to have an Air Pump was the North American B210 series for 1975. No Datsun 1200 was fitted with an air pump.

Overview

An engine driven pump, about the size of the alternator forces air into the exhaust passages.

Components:

• Air pump
• Air pump air cleaner. This is large disk mounted down by the Charcoal Canister
• Check valve before going into head. Prevents exhaust from backflowing into pump or air filter
• A.B. Valve (anti-backfire valve) between carburetor Air Cleaner and intake port (port on intake manifold). This valve has a single vacuum hose to control it. It prevents backfires in the exhaust system when during acceleration the richer naturally becomes richer, a condition the Throttle Opener also works on. However unlike the throttle opener, it dumps air into directly the intake manifold, causing it to lean out. This only occurs during decceleration so does not lean out the mixture when accelerating or cruising.

California models had these additions to prevent overheating of catalytic convertor:

• Air control valve
• E.A.R.V. (Emergency air relief valve)

or (later models):

• C.A.C. valve. One hose tees into the pump output, the other hose dumps to the air (apparently not connected to anything). This valve has a single vacuum hose to control it