350 TBI Exhaust Manifold AIR System

[zachc113]

Hey all,

I recently purchased a family members 87 K20 with a 350 TBI, It has had a true dual exhaust put on it with no cats. It has an audible exhaust leak at the manifold and along the secondary air injection system per a mechanic. That said I have done some reading with no great answer but I guess my questions is, should I delete the AIR system since the truck does not have cats on it any longer, and if so what manifold/header system should I look into? I will still need the Dung for the 02 sensor I presume so, that limits me to a few options; all with mixed reviews. Or I could do headers with a reducer and bung with a heated O2 sensor.

What is the best option for this setup or should I change something along the way.

I will also not the truck seems to run ok but does stutter and throw a lean code eve now and again. I am thinking this may be related to to the exhaust leak or a vacuum leak but would the truck not having cats potentially affect the o2 sensor as well?

Attached are a few photos of the current air setup and exhaust

 

[Grit dog]

You can ditch the AIR system with zero ill effects afaik. It’s downstream catalyst action and will not affect engine operation.
Can you just isolate the leak and fix it? It’s common to remove the air tubes and plug the hole in the manifolds. The jethro engineering way is cut the tubes and crimp them over with pliers.
Depends where the leak is and how bad you want to put aftemarket headers or manifolds on it vs maybe fixing it cheap n easy.

 

[zachc113]

You can ditch the AIR system with zero ill effects afaik. It’s downstream catalyst action and will not affect engine operation.
Can you just isolate the leak and fix it? It’s common to remove the air tubes and plug the hole in the manifolds. The jethro engineering way is cut the tubes and crimp them over with pliers.
Depends where the leak is and how bad you want to put aftemarket headers or manifolds on it vs maybe fixing it cheap n easy.

Cool deal, and potentially, cost isn't a huge deal for me on it I just would prefer it to work properly when complete. I don't see any visible cracks in the manifolds but theres definitely a leak around them somewhere.

Do most people delete the pump off the drive system all together? I have read several posts on the OBS trucks where they have to shorten their accessory belt but it appears on mine it is powered by an isolated belt with nothing else on it. Kind of hard to see but its down in one of the attached pics. Or is it common to let it run but just plug the manifold and crimp over the lines with everything attached? I do see a single plug going into a valve off the pump as well.

 

[fast 99]

If you delete the AIR system take the check engine light out of the cluster. ECM will detect a fault. Even if there are no inspections in your area defeating any part of the emissions system is federally illegal.

Really don't understand why people remove emissions parts without complete understanding of the entire system and how the modification will effect operation. In many cases will create drivability issues, complicate any diagnosis and accomplish nothing.

Go buy a cheap stethoscope at HF, find and repair the leak, nothing more.

edit, if you want proof look at the history here. There is at least 1 post a week about driveability problems or fuel smell and all the emission items have been ripped off.

 

[Grit dog]

If you delete the AIR system take the check engine light out of the cluster. ECM will detect a fault. Even if there are no inspections in your area defeating any part of the emissions system is federally illegal.

Really don't understand why people remove emissions parts without complete understanding of the entire system and how the modification will effect operation. In many cases will create drivability issues, complicate any diagnosis and accomplish nothing.

Go buy a cheap stethoscope at HF, find and repair the leak, nothing more.

Sage advice here. Despite my previous reply.
I didn’t think of the trouble code being an EFI truck. To be fair, the last one I disabled was in like 1990 on a 1981/82 K20. And I cut n crimped the lines and took the belt off and down the road she went. Every day pulling a landscape trailer no issues.
I also am of the opinion that the 0.00001% of classic vehicles driving around with defunct or missing 70s-80s emissions systems are somewhere about 100 levels below cow farts for depleting the ozone layer and adding pollution.
(Don’t look under my 2016 diesel pickup though…..just keep walkin’. Lol)

 

[Ricko1966]

Sage advice here. Despite my previous reply.
I didn’t think of the trouble code being an EFI truck. To be fair, the last one I disabled was in like 1990 on a 1981/82 K20. And I cut n crimped the lines and took the belt off and down the road she went. Every day pulling a landscape trailer no issues.
I also am of the opinion that the 0.00001% of classic vehicles driving around with defunct or missing 70s-80s emissions systems are somewhere about 100 levels below cow farts for depleting the ozone layer and adding pollution.
(Don’t look under my 2016 diesel pickup though…..just keep walkin’. Lol)

? Why? Did you hide cows under it?

 

[Grit dog]

? Why? Did you hide cows under it?

Hahahaha no but it kinda smells like an old School bus or Cat tractor now, it’s not emitting unicorn farts out the tailpipe anymore.

 

[JT58]

I took all mine off- pump, belt, pump bracket, the smog tubes, etc. The thread in the manifold is a M22 X 1.5- I had to do a lot of research to find out. The plugs I used were an oil drain plug for a Dodge Cummins truck 94-01- they have the same thread. Got them from Rock Auto, real cheap. They look good too, better than crimping the ends of the tubes.

 

[Grit dog]

If you delete the AIR system take the check engine light out of the cluster. ECM will detect a fault. Even if there are no inspections in your area defeating any part of the emissions system is federally illegal.

Really don't understand why people remove emissions parts without complete understanding of the entire system and how the modification will effect operation. In many cases will create drivability issues, complicate any diagnosis and accomplish nothing.

Go buy a cheap stethoscope at HF, find and repair the leak, nothing more.

edit, if you want proof look at the history here. There is at least 1 post a week about driveability problems or fuel smell and all the emission items have been ripped off.

And yet I have 3 old carbureted vehicles. No emissions on them, and drivability and exhaust smell are simply non issues. Even the one with side pipes.

 

[fast 99]

And yet I have 3 old carbureted vehicles. No emissions on them, and drivability and exhaust smell are simply non issues. Even the one with side pipes.

I was emissions certified in Washington. No longer checked today. They changed to forcing EV cars on us.

Anyway, I see nothing wrong with some of the emissions devices, air injection and cats are 2 of them. Neither will lower HP and reduce emissions by substantial amounts. Your early vehicles likely have a 1-1/2% + CO with 200+ ppm HC. With cat and air pump could be in the area of 1/2% CO and 50 ppm HC probably lower. I am not a tree hugger but there's no logical reason to remove either device unless it needs repair.

 

[Grit dog]

I was emissions certified in Washington. No longer checked today. They changed to forcing EV cars on us.

Anyway, I see nothing wrong with some of the emissions devices, air injection and cats are 2 of them. Neither will lower HP and reduce emissions by substantial amounts. Your early vehicles likely have a 1-1/2% + CO with 200+ ppm HC. With cat and air pump could be in the area of 1/2% CO and 50 ppm HC probably lower. I am not a tree hugger but there's no logical reason to remove either device unless it needs repair.

I think we’re talking apples and oranges here.
You’re generalizing this as all vehicles with emissions controls from the factory it seems.
Agreed, if I had a stock “antique” vehicle, as all the vehicles in the subject matter of this forum are antiques and it was cooking along just fine with AiR, EGR, cats etc, I would not touch them either if I had no reason to.

However, of the over 300million registered vehicles in the US and Canada, the almost indiscernibly small fraction of antique vehicles that are from the emissions era and not running factory emissions is of no real concern to the environment.
It’s like saying you’re doing your part to reduce water consumption by saving 1 toilet flush per day per 1000 people.

Not to minimize anyone’s desire to keep their emissions in tact or spend money to repair or replace old technology on a vehicle that is quite likely also not daily driven or high miles per year. But it is an act of zero or diminished return to think about doing it simply out of some fear of compliance for a law that is frankly unenforced and/or not required by local or state jurisdiction.
It seems like this discussion is more about being an antagonist when it comes to maintaining emissions systems than borne out of real world concerns.


Especially based on your last sentence and the original reason for this thread which was that of a repair needed either to or affecting someone’s AIR system.

 

[fast 99]

I am not suggesting installing either on a vehicle that was not originally equipped. My comments are aimed at folks that remove systems thinking they are improving anything. Also pointing out the massive emissions reduction without sacrificing any HP.

 

[Craig Nedrow]

I know some don't like headers, but they make HP, look good, and if you use good quality gaskets, don't leak. Adding extensions always make more power too.