Removal of Smog Control 74

scottevest

Well-Known Member
Site Donor
Messages
1,981
Reaction score
598
Location
Ketchum, Idaho
Don Lawrence suggested I remove the smog control "stuff" on my 74. He said they don't do much and merely hurt performance. He rattled off quickly what was involved, but too quick for me to write it down or remember.

My questions are:
  • is there a resource/list of the smog control things that can be removed and how?
  • would it help performance?
  • is it legal to remove these?
Thanks.
 

rsporsche

Moderator
Site Donor $$
Messages
10,634
Reaction score
3,671
Location
Atlanta, GA
is it legal? depends on which state you live in and what their laws are ... and how they check. in georgia, a car that is 43 years old - no problemo. california might be a different story. if you don't have to do smog testing in Idaho for a car of this age ... chances are you won't have an issue.

will it help performance - yes. if SFDon says it does, take it to the bank ... he knows.

can't help you with the list - my coupe doesn't have any of it to remove.
 

sfdon

Well-Known Member
Site Donor
Site Donor $$
Messages
8,148
Reaction score
4,470
Location
sfbay area
California exempts cars Before! 1976 ! from smog testing.
Smog equipment is bad for early cars
Never heard of a checklist.

In Ca we figure out where it is and how to get it out
 
Last edited:

WALTER

Well-Known Member
Site Donor
Messages
603
Reaction score
162
Location
WASHINGTON, D. C.
Don removed the smog equipment I had on a '74 I had a long time ago and the seat of the pants dyno confirmed that the car did seem peppier. This coupe was in CA and I had no problems registering it.
 

sfdon

Well-Known Member
Site Donor
Site Donor $$
Messages
8,148
Reaction score
4,470
Location
sfbay area
Google says in Idaho-

EXEMPTIONS
A vehicle is exempt from emissions testing when:

  1. It is a 1964 model or earlier.
  2. It is not registered or used in the Ada County.
  3. It is a motorcycle or a motor-home.
  4. It is a new vehicle and less than a year old.
  5. It has a manufacturer's gross vehicle weight rating less than 1500 pounds.
  6. It is registered as an Idaho Old Timer or Classic Vehicle.
  7. It is a farm-tractor.
  8. It is a vehicle registered on pro-rated basis.
  9. It is an alternative fuel vehicle.
 

scottevest

Well-Known Member
Site Donor
Messages
1,981
Reaction score
598
Location
Ketchum, Idaho
Just because a car is not subject to emission testing doesn't mean that it is legal to remove, right? My shop is concerned about liability.
 

jmackro

Well-Known Member
Messages
2,452
Reaction score
721
Location
San Juan Capistrano, Ca.
Just because a car is not subject to emission testing doesn't mean that it is legal to remove, right?

I'm not a lawyer, but yes, I would assume that just because a car is not subject to emission testing in a certain state doesn't mean that it is legal to remove the Federally-mandated emissions equipment. I can imagine a scenario where a shop removes equipment from a car which is later sold to a buyer in a state that requires testing. When the car fails because the emission parts are missing, the buyer is going to try to recover his purchase price, state penalties, pain and suffering, etc. from whomever's fingerprints are on the car.

Not to sound holier than thou - I have done this sort of thing on my own pre-1976 cars (which are exempt from emissions testing in my home state). But as an amateur mechanic I can plead ignorance. A professional mechanic would have a tougher time saying they didn't understand emission equipment isn't optional.
 
Last edited:

aearch

Well-Known Member
Site Donor $
Messages
4,106
Reaction score
588
Location
pleasant hill , ca
you dont need smog on 74 and backin calif
and if its not cvhecked
its a no brainer to remove it all
including the cats if there
thats how i built my straight exhaust snake headers and the s38b36
or no luck
thats why i bought the 74 ans not later year.
 

scottevest

Well-Known Member
Site Donor
Messages
1,981
Reaction score
598
Location
Ketchum, Idaho
My local Boise shop reported:

The removal of smog related components is apart of the Federal CAA (Clean Air Act). According to Ada County Air Quality Board it is punishable by a minimum of 1 year prison and $10,000 fine. https://www.epa.gov/enforcement/enforcement-basic-information

So, even though my state and most states don't test 1974 vehicles, removal of any smog stuff may be illegal from the US Federal Government. I don't want to goto jail over this...

Any thoughts?
 

scottevest

Well-Known Member
Site Donor
Messages
1,981
Reaction score
598
Location
Ketchum, Idaho
Scott, I have no idea whatsoever how to make that determination. I am bringing the car back to SF in November to have Bill Arnold tune and install carbs and check it out thoroughly, and will have him confirm.
 

aearch

Well-Known Member
Site Donor $
Messages
4,106
Reaction score
588
Location
pleasant hill , ca
there is no way anyone will check your car for smog
esp a 74
the only people who see it is the dmw registration and
they dont check any more
no brainer.
id love to see the fbi check for smog!!!
 

rsporsche

Moderator
Site Donor $$
Messages
10,634
Reaction score
3,671
Location
Atlanta, GA
actually that was said with tongue firmly planted in cheek. i'd have Bill let it fall off of the car ... maybe help / persuade it a bit. as far as you know, it was that way when you bought it - right?
 

mulberryworks

Mr. Fixity
Site Donor
Messages
1,243
Reaction score
612
Location
Jacksonville FL
In answer to your original question of:
  • would it help performance?
I can't speak directly to the control/tuning of the M30 engine by BMW, but we had a '74 Pontiac and the emission rules made the V8 engine be so mistuned that even after a tune up from the dealer, it ran very poorly when cold and even warmed up, the mileage was poor, around 13 mpg if I remember correctly (but I wasn't buying gas then).
In 1975, Detroit (not BMW) switched to catalytic converters to clean up the exhaust and could tune the engine to run better, albeit dirtier.

I think the only emission equipment my 1970 2800cs has is a dashpot, a sort of shock absorber to keep the throttle butterflies from slamming closed on throttle off which would cause the mixture to go really lean and hence burn incompletely.

Ian
 

scottevest

Well-Known Member
Site Donor
Messages
1,981
Reaction score
598
Location
Ketchum, Idaho
In answer to your original question of:

I think the only emission equipment my 1970 2800cs has is a dashpot, a sort of shock absorber to keep the throttle butterflies from slamming closed on throttle off which would cause the mixture to go really lean and hence burn incompletely.

Ian

Was this ever proven to be less polluting method, or a failed attempt? I want to be sure that no one accuses me of doing something bad for environment.
 

mulberryworks

Mr. Fixity
Site Donor
Messages
1,243
Reaction score
612
Location
Jacksonville FL
It was a way of lessening the pollution enough to meet the 1970 emission standards. VW beetles had the same dashpot arrangement. They worked on the simplest, and maybe the dirtiest things first. I suppose the timing might have been changed a bit to help prevent NOx creation, but I don't know the specifics.

1968 was pretty much the first year of any emission standards and they were pretty easy to meet the first two years. Then each year they started ramping them up until 1975 when the US carmakers couldn't meet them without cats. BMW used thermal reactors which was the same idea, but no rare elements for catalysts and to work, it had to be closer to the engine which caused some cracked heads. They are part of the exhaust manifold, most people remove them.

Now that we have fuel injection, we are delivering just the right amount of fuel, at just the right time and the engines deliver more power with less pollutants. Current production standards require a three way cat, but that's nothing to do with our cars.

I believe the federal penalties apply to a shop that removes pollution equipment. As an individual, since the cars are never tested, no one would come after you.
By keeping a well tuned car, you are doing the best to reduce pollution possible for such an old car. If you really want to do better than stock, you could install a newer engine with either it's stock FI setup, Motronic 1.3 from a 1988 car is best, or maybe Megasquirt, which is very DIY unless you hire it out to knowledgeable people. You could keep the cat as well, since the O2 sensors are part of the FI system. I like the idea of a clear running car, but that's a lot of work, and expense.

I'm staying stock with my two Zenith carbs and the 2.8L M30. Besides, its a number matching engine.

Ian
 

Ohmess

I wanna DRIVE!
Site Donor $
Messages
4,833
Reaction score
2,639
Location
Aiken, SC
Was this ever proven to be less polluting method, or a failed attempt? I want to be sure that no one accuses me of doing something bad for environment.

Scott -- you cannot drive a car with carbs and avoid being accused of doing something that is bad for the environment. The reason carbs disappeared is that they cannot be made as clean as fuel injection when the engine is cold. Thus, they are dirtier when you first start and run them. Also, when you hit the accelerator hard, they dump a large amount of fuel into the engine and this too is not as clean as a more precisely metered fuel injection system. And indeed the fact that the carbs expose a certain amount of fuel to the atmosphere in order to use the pressure differential between the atmosphere and engine vacuum to emulsify fuel means that our cars release gasoline fumes after we shut them off. No 1970s system is going to change these things and make a carbureted car as clean as a fuel injected car with a closed fuel system.

Moreover, I strongly suspect you could not find anyone to get a 1970s system to work perfectly in one of our cars. In the US, the vast majority of them were junked long ago, and I doubt even the factory would have maintained the expertise for a US/Canada only system.

As to the concern expressed by your shop, my understanding is that the EPA fines pertain only to the removal of catalytic converters. I don't think BMW employed catalytic converters on the e9s, so your shop should be able to remove the other stuff. Of course, I am not a lawyer so take this for what you paid for it.
 
Top