Removing emissions......what is this???

[SASKCHEYENNE75]

Good morning. I have recently acquired a 1975 Chev C10 with a 350 4bbl. The truck is completely stock for the most part. I am going to start removing some of the emissions crap on it as where I live there are no emissions laws (Canada). I have looked into removing the EGR and blocking it off, as well as, the smog pump and I understand how to do those. My question is what the heck is this thing??

I also noticed that there is a bracket right beside the smog pump that has nothing attached to it...I'm assuming the smog pump was bypassed however all the hoses etc are still there including the metal lines attached to the stock exhaust manifolds. Thanks!!

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[Bextreme04]

Good morning. I have recently acquired a 1975 Chev C10 with a 350 4bbl. The truck is completely stock for the most part. I am going to start removing some of the emissions crap on it as where I live there are no emissions laws (Canada). I have looked into removing the EGR and blocking it off, as well as, the smog pump and I understand how to do those. My question is what the heck is this thing??

I also noticed that there is a bracket right beside the smog pump that has nothing attached to it...I'm assuming the smog pump was bypassed however all the hoses etc are still there including the metal lines attached to the stock exhaust manifolds. Thanks!!

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That the actuator for the valve in the exhaust that restricts flow to push the exhaust through the crossover in the intake. Lots of people remove and/or bypass the valve because they are prone to failure and can cause major issues if they stay closed once the vehicle warms up, but you would be sacrificing how it runs when cold and how fast it warms up.

 

[Bextreme04]

Its not strictly an emissions device as much as it helps with cold weather driving and cold starts. Being in canada, I'd suggest you verify proper function of the actuator and valve and then leave the whole system including intake and heat riser pipe. I'd definitely get rid of the smog pump and EGR though as they don't really serve a valid function.

 

[SASKCHEYENNE75]

Its not strictly an emissions device as much as it helps with cold weather driving and cold starts. Being in canada, I'd suggest you verify proper function of the actuator and valve and then leave the whole system including intake and heat riser pipe. I'd definitely get rid of the smog pump and EGR though as they don't really serve a valid function.

Good to know! I'm not really sure how to verify its working properly...any suggestions? It is cold here and although I don't plan on using it much in the winter it's still important to make sure it's running properly if I do. And yes I'll certainly remove the smog pump and EGR.

 

[SASKCHEYENNE75]

Also what is the big hose coming up out of the passenger side exhaust manifold? Is that something that should be eliminated?

 

[Octane]

The EFE system works to warm engine faster as a cold engine pollutes more.Even the engine timing was retarded down to 4° on a 70s chevy 350 I had to make The Peoples Republic of Kalifornia happy back at the time.

 

[Bextreme04]

Also what is the big hose coming up out of the passenger side exhaust manifold? Is that something that should be eliminated?

Its a simple valve. I'd just start with a cold truck, start the truck and watch the arm to see if the valve moves as the truck warms up. The metal pipe running from the manifold up to the intake is the heat riser. It runs warmer air up into the intake when the truck is cold. Once it warms up, that valve right above where it goes into the intake will close a valve inside the intake and block it off to start sucking in cold air instead. It is also for cold weather driving and I would leave it.

 

[Octane]

Also what is the big hose coming up out of the passenger side exhaust manifold? Is that something that should be eliminated?

The plastic,or sometimes metal hose than hooked to exhaust manifold and ran to breather housing intake was to move that warm air to the carb etc to warm engine also.It hurts nothing to leave it hooked up as long as the thermostic baffle opens and closes properly that is in the snorkel as it warms and cools.I didnt notice this was addressed in the other post.Looks like we posted at same time

 

[SASKCHEYENNE75]

Its a simple valve. I'd just start with a cold truck, start the truck and watch the arm to see if the valve moves as the truck warms up. The metal pipe running from the manifold up to the intake is the heat riser. It runs warmer air up into the intake when the truck is cold. Once it warms up, that valve right above where it goes into the intake will close a valve inside the intake and block it off to start sucking in cold air instead. It is also for cold weather driving and I would leave it.

Thanks for the help!!

 

[SASKCHEYENNE75]

The plastic,or sometimes metal hose than hooked to exhaust manifold and ran to breather housing intake was to move that warm air to the carb etc to warm engine also.It hurts nothing to leave it hooked up as long as the thermostic baffle opens and closes properly that is in the snorkel as it warms and cools.I didnt notice this was addressed in the other post.Looks like we posted at same time

Appreciate the help!!

 

[Ken B]

I was wondering about removing all the smog stuff. I will watch this thread to follow your progress. I have a 350 that I need to get all the smog stuff off that isnt necessary. I do not know much about this "extra" equipment.

 

[SASKCHEYENNE75]

I was wondering about removing all the smog stuff. I will watch this thread to follow your progress. I have a 350 that I need to get all the smog stuff off that isnt necessary. I do not know much about this "extra" equipment.

I'll post pics as I go!

 

[Ken B]

appreciated!

 

[80BrownK10]

https://www.gmsquarebody.com/threads/what-is-this-exhaust-part.32166/#post-642657

See this thread. I just asked about this part. I was missing everything else. The part in my picture in my thread is what the part in your picture is hooked too with a metal rod. You will get the idea of what it does. Just a flap in the exhaust.

 

[Ricko1966]

Do your research on EGR. There is zero benefit in disabling working EGR but several disadvantages. Better MPG, cooler combustion chambers, ability to run more timing. The simplest way I can describe this is at low load conditions a partial charge of exhaust gas( inert) dilutes the fresh air and fuel charge so the re is less oxygen and fuel in the combustion chamber. Less burn means less heat and less fuel consumption.It is inop cold and it is inop on acceleration or under load. So no more power at WOT .

Think of it like this, and these are not actual numbers but numbers to make operation understandable. At cruise speed the EGR valve opens and allows the cylinder to fill 1/2 with exhaust gas 1/2 with air/fuel, so you burn 1/2 as much fuel,step on the gas pedal, the EGR valve closes and now you are burning only air and fuel, power goes up mpg goes down.