Catalytic converter necessary?

sterling

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I have a cat on my 79 40 that was put on there by po.
Don't need it for emissions anymore.

Question is do I need it at all? Mainly does it help with the gas smell we are all blessed with?
Is it worth my time to take it to scrap yard? I'm pretty sure its sawzall time just wondered if I benefit from keeping it.

Thanks all.
 

sterling

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only does what it is supposed to do if there is an air pump to go with it.
Thanks @brian. I have the Jim C pulley so no go there. Is it worth anything scrap wise?
 

pb4ugo

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Thanks @brian. I have the Jim C pulley so no go there. Is it worth anything scrap wise?
Yes, it has value at the scrap yard. Idk how much, thieves seem to be cutting the off all the time.
 

Engineer8000

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If it is a newer aftermarket catalytic converter then an air pump is not required, from what I have read. The older ones needed the air pump or they would break down and possibly clog up the exhaust stream.
 
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Unless yours is a not a US import the CAT was installed by Toyota and possibly replaced by a PO. But it had one from the beginning.
You can thank the CAT for the exhaust being routed below the frame by the firewall on 79/80 models. Non CAT markets exhaust ran over the fre. 8/80 Toyota added a heat shield on all 40 series ran it over exhaust over the frame. Doubt we will get it in the US but the Heritage program is offering the header pipe over the frame and next piece of exhaust that
eliminates the CAT and bolts directly to the muffler.

The purpose of a CAT is to burn off unburnt fuel. Even stand alone it helps do that. Here in AZ CAt theft is a big problem. Toyota has more precious metals which makes them a bigger target. It is regulated who can buy CATs to be recycled which requires a record of vehicle it was removed from. Which be a vehicle being slavaged or a CAT being replaced. Whe the CATs first appeared leaded gas was still being sold. If leaded gas was used in a CAT equipped vehicle would plug up the CAT over time. Worked for a company big enough they did their owned emissions testing. Also had their own gas pumps. I had a late seventies Ford pickup that the had the CAT plug up so bad it barely ran. Only gas they had was unleaded. AZ has some of the strictest emissions going back to 1967. That is only in certain parts of the state. Rest no emissions are required. On the fence about my 79 still it is out of an emissions area. If I could get the two non US pieces would probably remove the CAT and hang on to it. Only piece left is the muffler/tailpipe which I have a new one to install.
 

sterling

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If it is a newer aftermarket catalytic converter then an air pump is not required, from what I have read. The older ones needed the air pump or they would break down and possibly clog up the exhaust stream.
Its newer, very shiny in fact. I have had the truck for 10 plus years .Thanks for the info.
 

Spike Strip

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I have a cat on my 79 40 that was put on there by po.
Don't need it for emissions anymore.

Question is do I need it at all? Mainly does it help with the gas smell we are all blessed with?
Is it worth my time to take it to scrap yard? I'm pretty sure its sawzall time just wondered if I benefit from keeping it.

Thanks all.

No, you don't need it if you're not subject to emission inspection.

It helps greatly with exhaust smell, though a properly-tuned (including carburetor) truck without a CAT should not smell, much. Well-burned exhaust will have a smokey musty smell.

Benefit is reduced smell and lowered emissions. CAT is not so much for unburned fuel, as it is for taking burned gases (HC, CO and NOx) and catalytic reacting them together to form H2O, CO2 and small quantities of N2 (In theory).
 

sterling

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No, you don't need it if you're not subject to emission inspection.

It helps greatly with exhaust smell, though a properly-tuned (including carburetor) truck without a CAT should not smell, much. Well-burned exhaust will have a smokey musty smell.

Benefit is reduced smell and lowered emissions. CAT is not so much for unburned fuel, as it is for taking burned gases (HC, CO and NOx) and catalytic reacting them together to form H2O, CO2 and small quantities of N2 (In theory).
Thanks @Spike Strip, that makes sense (in theory).
 

Downey

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I'll try to remember this history correctly: many catalytic converters have a replacement monolith converter option (still smog legal/exempted). Monolith's are a straight through design (exhaust passes through a screen), no catalyst to restrict exhaust flow. When we tested a monolith install (added into a non-smog exhaust system merely to reduce emissions) we tested zero loss of h.p. and m.p.g., dynamometer results did not change. We did, however, gain a reduction in exhaust noise, the monolith worked like an extra muffler.
 

1911

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FWIW, I removed my cat converter after de-smogging and replaced it with a straight pipe. Less heat under the floorboard and no gas smell in mine.
 
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If it is not causing problems, I would keep it. It is about the only smog reducing product that actually works. Since these vehicles are not high performance, it most likely isn't hurting anything.
 

Downey

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Also, installing a fresh Cat on a rig that is failing the smog test (whether it is required or not) almost always then passes the test, normally because all you had to do is make an improvement.
 

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