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.