'78 SC: catalytic converter questions.

Folks:

The PO disconnected the air pump on my 3.0, so I assume I haven't been "cleaning" the catalytic via the puffs of air.

How would I know that the cat. is clogged? Next, what's the average $$ for these (unable to get quote from suppliers). Next, what sort of flak do you get for putting in a bypass pipe as per Pelican's item? Is this a bolt-in item the home mechanic can handle?

Thanks much,
John

John - if your cat is clogged you will be down on power and fuel mileage with an increase in engine heat. If you live in an area that doesn't require smog equipment I'd take it all off. The function of the air pump is to lean out the fuel mixture by diluting the exhaust gasses as they exit the engine. This "trick" helps pass emission testing.

Ah, I think I see: so the air pump leans out the mix after leaving the combustion chamber? That is, it has nothing to do with the mix that goes into the chamber, but rather with the resulting gases? I must say that is quite a way to go: just adjust the gas mix that the sniffer will detect so that it is up to snuff--pretty clever.

Right now I am getting 20 plus MPG and I pass emissions with flying colors. Guess I'll consider putting the bypass on.

jw

The air is pumped into the exhaust stream right behind the exhaust valve. The intent is to provide more oxygen to support further combustion of unburned components in the exhaust.