Smog equipment removal. Yes or No.

[1981suburban]

Hello. I am sure many members have done this before. Most of the cars I deal with are pre-smog. This Suburban was owned by an older Gentleman who never made any mods. It is factory stock. It looks like the removal of the smog crap would be relatively easy. It has the factory exhaust manifolds, so I assume the smog lines running in them can be plugged (I don't have the car funds for headers at the moment). Should I remove the smog system, or just leave it on the vehicle? Any advise would be appreciated. It is a 1981 with a 350. Thanks!

 

[DoubleDingo]

I'd just leave it on. It doesn't hurt anything, and it really isn't robbing any power from the motor.

 

[77 K20]

On my '86 GMC Jimmy I just pulled the belt for the air pump then I found a shop to run true dual exhaust on it. It helped out that old tired 305.

Of course I don't have any emissions or vehicle inspection here.

 

[smoothandlow84]

All the air pump (aka smog pump) does is pump air into the exhaust manifold to clear out heavy pollutants during idle. Removing the air pump or at minimum the drive belt to it will put less load on the motor. In theory you are robbing a little bit of power from the motor with it running along with the motor. I ditched mine since I am emission exempt with my "collector car insurance...Haggerty" My truck is registered as a collector vehicle in my home state so no emissions for me. If you get headers, then there is no point in keeping the air pump or any of the related components on. The engine compartment is so much cleaner with all that removed.

 

[flyboy1100]

If you do remove it, you can plug thing manifolds with an oil drain plug. Can't remember the size right now, but for a decent sized diesel. 20mm i think, i know for sure it was metric thread.

 

[smoothandlow84]

Also a good idea to soak the threads of the oem smog fitting that are in the manifolds with wd40 or penetrating oil. Those boogers have been baking in there for over 30 years and tend to put up a fight when trying to remove them.

 

[MikeB]

I suggest your read the shop manual to get familiar with what the various emission controls do, and then make a decision. Plugging a hose here and there could effect spark advance, idle quality, prevent the fule tank form venting, etc. Here are some notes I made on my 82's emission systems when it had a 250 six:

TVS: Thermal Vacuum Delay Switch (coolant)
Page 6E-13
Delay switch opens as coolant temp rises, permitting the ported vacuum signal to reach the EGR valve. (Is this used with EFE?)

There may also be an Oil Temp TVS. In fact this may be what the 250 six uses to control EFE. Page 6E-16
Also, the Thermac Air Cleaner TVS senses air temp.

EFE: Early Fuel Evaporation
Page 6E-2 and 6E-15-6E-16
Supplies a source of rapid heat to the induction system during cold “driveaway”. Should “turn off” after engine warm-up.

The Vacuum Servo type uses a valve and vacuum actuator which increases the exhaust gas flow under the intake manifold during cold engine operation. The valve is located in the exhaust and is vacuum operated. It is controlled by a Thermal Vacuum Switch (TVS), or an EFE solenoid controlled by the ECM. When vacuum is applied, the valve closes, causing the intake to heat up.

Watch the actuator arm when the engine is started. The valve should close when the engine is started cold; the actuator link will be pulled into the diaphragm housing.

Also see http://www.autozone.com/autozone/re...l-Evaporation-EFE-System/_/P-0900c15280055ca7

PAIR: Pulse Air Injector Reactor System
Page 6E-4, 6E-21 to 23
Controlled by Pulse Air Valve

Deceleration Valve – used on 250 six
Page 6E-23

TRC: Throttle Return Control System
Page 6E-27

TVS: Trapped Vacuum Spark
Page 6E-28
A TVS (sensor) senses coolant temp. When engine temp is BELOW a specified value (???) manifold vacuum signal is routed through a check valve to distributor, and ports on TVS are blocked. This allows full vacuum to distributor even during acceleration. Small bleed valve allows vacuum to escape when engine is shut off.

When coolant temp is ABOVE specified value, manifold vacuum is applied to distributor, but check valve is open, so vacuum to dist varies under load.

 

[1981suburban]

Great. Thanks for all the help fellas! I think I will keep it on for now, until I get ready for headers and new exhaust.

 

[MadOgre]

To run with out all you need to do is remove everything and plug ports in intake or just simply disconnect all vacuum hoses. Then simply run a vacuum hose to the distributor off of any of the full manifold vacuum sources. If you have the 700r4 then you use full vacuum with that as well, for the torque converter switch.

Other than that you will need to keep your PCV system which is very simple. Fresh filtered air usually goes in on the passenger side valve cover and then the PCV valve is located on the opposite side (drivers front valve cover) and is routed to the large port on the front base of the carb so it can draw the crank case blow by gasses into the intake to be burnt again.

It really is quite simple and is as easy as simply removing all vacuum hoses and starting over

An 81 has no electronic anything. Not sure if you have cruise? If you do you will want to ensure that you don't disconnect anything related to that

 

[1981suburban]

To run with out all you need to do is remove everything and plug ports in intake or just simply disconnect all vacuum hoses. Then simply run a vacuum hose to the distributor off of any of the full manifold vacuum sources. If you have the 700r4 then you use full vacuum with that as well, for the torque converter switch.

Other than that you will need to keep your PCV system which is very simple. Fresh filtered air usually goes in on the passenger side valve cover and then the PCV valve is located on the opposite side (drivers front valve cover) and is routed to the large port on the front base of the carb so it can draw the crank case blow by gasses into the intake to be burnt again.

It really is quite simple and is as easy as simply removing all vacuum hoses and starting over

An 81 has no electronic anything. Not sure if you have cruise? If you do you will want to ensure that you don't disconnect anything related to that

Thanks for the info Orge. It does have factory cruise. After a further inspection, I think you are right. Pretty simple to take off and plug. It sure would make the engine bay look cleaner. Not to mention it would make any further engine work a heck of a lot easier, not having to fight all the BS.

 

[smoothandlow84]

I pulled the pump, belt, bracket, manifolds and the attached tubing from the pump to the air filter housing. I have been driving it without any issues or check engine lights. The only part of the plumbing that remains are the two metal tubes thatnattach to the back of the manifold that used to connect to the manifolds. Eventually they will be ditched as well. I did replace the rubber tubing since the old ones were dried up. I dont have any vacuum lines attached to my distributor (hei distributor no vac advance connection). Idles smooth, runs great and noticeable power increase since the header install.

 

[1981suburban]

Hmmmm. I like the looks of a cleaner engine bay. That smog **** sure gets in the way. I have no emission issues here, so it would not be a big deal to remove the system (which is a stupid design, let's be clear). I may just remove it and throw it in a box. Who knows? Maybe Suburbans in 20 years will be worth a lot, since everyone uses them as crew cab donors.

 

[smoothandlow84]

Exactly...all my smog crap is working just fine sitting in a box on a shelf in storage. It works great there. Its nice to have more room to wrench on tthings under the hood. Hell...I also ditched the massive plastic milk jug coolant recovery tank. I replaced it with a nice polished stainless steel canister from jegs. Plastic deteriorates, cracks, leaks and looked horrible after 30 some odd years of being under the hood. Next I'm gonna replace the windshield washer fluid tank as well with a stainless steel tank. Just like my overflow tank, it too will be mounted next to the radiator out of the way.

 

[Joe383]

I don't like the smog stuff it puts carbon rich exhaust gases back in to the motor and is hard on the motor shortening the life of the engine in exchange for cleaner exhaust gasses. The system is a whole though. Don't take the smog pump off with out taking the rest of the system off. I had a friend just take the belt off and it did not idle rite and popped out the exhaust just off idle. When you do the headers ditch the whole system cats and all. If you don't have some its pointless to have any.

 

[Georgeb]

Exactly...all my smog crap is working just fine sitting in a box on a shelf in storage. It works great there.

Amen to that ^^^

Mine, cats and all is going in to the scrap man!