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Air To Catalytic converter connection

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Old Jan 21, 2019 | 07:54 AM
  #1  
Hawgtied's Avatar
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From: Crosby, Texas
Car: 1988 IROC "The Duece"
Engine: 5.7 TPI L98
Transmission: 700R4
Air To Catalytic converter connection

I ran into a problem when I re-did my exhaust. I installed a new cat with the air injection port and when I removed the old one, which was held on with a U-bolt, I removed said U-bolt and had to cut the tubing because of the crimp the U-bolt created. My dilemma now is how do I connect the tubing from the air pump to the cat? The part I had to cut was flared to fit over the port on the converter. Is there a tubing union that will work? looks to be close to 3/8" tubing but I could be wrong. Any suggestions?
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Old Jan 21, 2019 | 08:55 AM
  #2  
GEN Xer's Avatar
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From: South of Dallas
Car: Formula 350
Transmission: A4
Axle/Gears: 3.27
Re: Air To Catalytic converter connection

Originally Posted by Hawgtied
I ran into a problem when I re-did my exhaust. I installed a new cat with the air injection port and when I removed the old one, which was held on with a U-bolt, I removed said U-bolt and had to cut the tubing because of the crimp the U-bolt created. My dilemma now is how do I connect the tubing from the air pump to the cat? The part I had to cut was flared to fit over the port on the converter. Is there a tubing union that will work? looks to be close to 3/8" tubing but I could be wrong. Any suggestions?
I did the same job about a month ago- I ended up using some "hi temp" rubber hose from the local parts supply- it's only a temporary fix but all seems fine so far. The appropriate fix would be to either reflare one end and braze/weld or add a coupling. There's always air pumping through this cooling it so the heat from the cat won't burn it. At any rate it will last until you can find an exhaust shop. This fix has 100~ miles or so and shows no sign of heat damage- also it doesn't hang below the cat, it's just the angle of the shot.



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Old Jan 21, 2019 | 09:22 AM
  #3  
BovineZro's Avatar
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From: Nederland CO
Car: '91 Camaro Z28
Engine: L31 5.7
Transmission: T56
Axle/Gears: 10 bolt, 3.73
Re: Air To Catalytic converter connection

For what it's worth, I have the same temporary fix in place (hi temp hose with hose clamps). I've put just over 200 miles on the car with no issues. I wouldn't leave this in place permanently though.

If you don't have enough length in your existing AIR tubing to reach the new cat, I'd imagine you could get a section of steel tubing to make up the difference (rather than replacing the entire length of tubing). You could flare both ends of the steel tubing so it fits over the existing AIR tubing and the port on the cat or just use tubing with a slightly larger inner diameter than the outer diameter of the AIR tube and cat port. It wouldn't be the cleanest thing in the world.
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Old Jan 21, 2019 | 01:47 PM
  #4  
gpwasr10's Avatar
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From: Los Lunas, NM
Car: 1989 Iroc-Z Hardtop
Engine: L98
Axle/Gears: 9 Bolt 2.73 Posi
Re: Air To Catalytic converter connection

Originally Posted by GEN Xer
I did the same job about a month ago- I ended up using some "hi temp" rubber hose from the local parts supply- it's only a temporary fix but all seems fine so far. The appropriate fix would be to either reflare one end and braze/weld or add a coupling. There's always air pumping through this cooling it so the heat from the cat won't burn it. At any rate it will last until you can find an exhaust shop. This fix has 100~ miles or so and shows no sign of heat damage- also it doesn't hang below the cat, it's just the angle of the shot.


What size tube is that? I may run into the same problem.
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Old Jan 21, 2019 | 03:40 PM
  #5  
GEN Xer's Avatar
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From: South of Dallas
Car: Formula 350
Transmission: A4
Axle/Gears: 3.27
Re: Air To Catalytic converter connection

The hose is 1/2 inch I.D. and it fit perfect. The likelihood you can find the correct size compression coupling is slim to none.
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Old Jan 21, 2019 | 11:27 PM
  #6  
LAFireboyd's Avatar
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From: Las Vegas
Car: 1987 Formula (original owner)
Engine: 305 TPI
Transmission: T5
Axle/Gears: 9-bolt/3.45
Re: Air To Catalytic converter connection

Compression fitting. Muffler shops sold a repair kit with the hose, but I knew there had to be something better fitting and better looking. Don't remember the size of the fitting, but it's not an odd size, and it fit perfectly.
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Old Jan 22, 2019 | 04:16 AM
  #7  
GEN Xer's Avatar
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From: South of Dallas
Car: Formula 350
Transmission: A4
Axle/Gears: 3.27
Re: Air To Catalytic converter connection

Originally Posted by LAFireboyd
Compression fitting. Muffler shops sold a repair kit with the hose, but I knew there had to be something better fitting and better looking. Don't remember the size of the fitting, but it's not an odd size, and it fit perfectly.
That's sweet if anyone finds one throw up a link.
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