faced with a new Y pipe, and wondering if I need new converters?

ChryslerCruiser

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My wye pipe is rusted at the junction of the two banks of cylinders... AND the previous owner pulled the vacuum control off the vacuum pump.

Does that mean that the vacuum pump has not been supplying air to the converters? Or does the vacuum port on top of the vacuum pump actually shut off the vacuum to the converters? I am under the impression that no supplemental air to the converters will kill them, is that true?

What I am wanting to do, if the converters are still "good" is to reuse them by rebuilding my wye pipe. Is this feasible and realistic?

What are your thoughts?
 

Aspen500

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If your cats aren't plugged or rattling, I wouldn't worry about it. Air is injected to get the cats up to temp quicker. They only really start "converting" around 750°. Not having air injection working won't hurt them, UNLESS air was being injected constantly, which could cause them to melt. Operating temp is 750° -1,450°. If the cats were hot enough to melt the core, the casing would glow bright red, and they would be plugged though. Long way of saying, yours are probably fine, lol
 

Remow2112

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Do you have emissions testing there? If not, pull the cats and get a dual exhaust setup. You could also pull the air pump which are notorious for seizing up.
 

81ImpNC

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My 81 Imperial has a Y pipe with 2 pre-cats off the manifold and a main cat under the front seat that is fed air from the AIR pump. The Y pipe eventually degraded to the point I just had to replace it. My exhaust man gave me two choices 1) Reconstruct the Y pipe by hand with universal cats and pipe or 2) Just run two pipes with a resonator back from the motor and call it a day. I chose #2.
 

ChryslerCruiser

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I am pretty sure I need converters here in VT to pass inspection... NOT sure where I can get two pre-cats tho.. The main converter is probably not hard to source...
 

AMC Diplomat

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ChryslerCruiser

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Do you honestly think that an inspector will know what a 40 year old car is supposed to have?

Also, vehicles 16 years or older are emissions exempt in VT: Vermont exempts vehicles older than 16 years from emissions test

Yes vehicles older than 16 are exempt from emissions tests, but all vehicles need converters that originally had them... and with my luck Yes the inspector would know...

I would like to build a system that is like the 79 model year dual exhaust, single outlet... but will probably try and re-use the converters I have and build/replace the pipes that are needed.
 

Mikes5thAve

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I would stick with a main cat only. At least you have one so you're legal, it'll probably work better then what was there to begin with and for the y pipe you can argue that a replacement is no longer available but you've done your due diligence keeping one and that it does pass an emissions test.
Plus I think at least one on the y-pipe has the pipe on the side of the cat which is a bit unusual to replace.

Also aftermarket no cat y-pipes do get made in batches from time to time and are available or a muffler shop should be able to make one for not too much.
 

Camtron

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No one is going to know these cars came with two pre cats and a main catalytic converter, they will pass you so long as you have a catalytic converter. VT doesn’t even say they’re looking for modifications, just that a CAT is present on the vehicle.

You’ll be fine without the two pre CATs.
 

AMC Diplomat

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we need to stop advertising what the original equipment was on these cars. it'll start showing up in google searches!
 
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