At 07:35 PM 3/12/2001 -0500, Chris Thompson wrote:
>On Mon, 12 Mar 2001, Andrew B. Lundgren wrote:
>> They idea is that they will pump more oxygen into your exhaust allowing
it to burn further in the catalytic converter. ....
>
>Then what was the air pump used for from 1969 to 1974 when the MG had no
catalytic convertor? ....
Before cat's the air pump was (for the most part) pumping air into the
exhaust port, as close as possible to the exhaust valve, where the exhaust
gas was still as hot as possible when exiting the cylinder. With the
exhaust gas still at a temperature in excess of the kindling temperature
for gasoline, the fresh air being injected would promote the completion of
combustion of hydrocarbons in the exhaust (unburned gasoline).
When the engine is in good tune the air injection makes very little
difference. But if the engine gets out of tune and running badly, or if
you leave the manual choke on too long, then the injected air can help to
reduce hydrocarbon emissions considerably. Now figuring that when a car is
run through a state emissions test it is already up to full running
temperature adn the choke is off, and hopefully the engine is in good tune,
then the air pump is generally excess baggage.
Barney Gaylord
1958 MGA with an attitude (and no emissions requirements)
http://www.ntsource.com/~barneymg
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