i was wondering when did they start making it mandatory to have a catty on your exhaust system, like what year vehicles do you have to have them on?

 

Think that all started in teh 70s. Seems my 77 F150 had a cat, but not really sure. I know it required no-lead and maybe that was done to prevent poisoning the cat.

 

1974, some were a year earlier, some a year later, as some could meet the specs w/o the cat for that year.

Lead does coat the catalyst rendering it ineffective. The move to get rid of lead goes beyond the cats though, as having lead spewing into the air you breath is madness.

Heavier GVW rated vehicles did not get cats until later dates.

Hate the cat if you must, but it allowed the engines to (eventually) be tuned for power again. That and efi gets you things like 281 CI Mustangs running quarter miles as quick as Boss 429s....

 

In CA, '75 and earlier vehicles are not subject to emission testing. Anything goes.

 

so a 95 f-150 would require a cat to pass inspection

 

Absolutely

 

The following is a section from an outline i did a few years ago for a large report on Emmision regulations in the US. This is the timeline section of my outline.

"A. The Clean Air Act of 1970 and subsequent revisions in 1983, 1990, and 1994 all limited the amounts of pollution that new cars could release
B. 1970-71
1. standard compression ratios were lowered, and carburetors tuned leaner
2. electronicly controlled carbs and ignitions were introduced
3. catalytic converters slowly introduced
C. 1972-75
1. compression ratios lowered even more to accept 87 octane gasoline
2. catalytic converters installed as stock on most passenger cars.
a. Catalytic converters use a chemical reaction to convert harmful CO gasses into water vapor, they became part of the standard exhaust system
3. air injection became common
a. air injection is a process in which air is entered into the exhaust system to oxidize CO and CO2 pollutants to keep them from entering into the atmosphere
4. also exhaust recirculation valves became common
a. these returned some exhaust gas back to the combustion chambers in an attempt to burn off more pollutants
D. 1976-80
1. more of the same
a. vehicles massively detuned
b. compression ratios lowered (again)
2. Positive Crankcase Ventilation (PCV)
a. PCV valves direct escaped exhaust gasses from around the pistons back into the intake manifold to be burned again
E. 1983
1. after protests from auto manufacturers CO standards were lowered from three point for (3.4) gpm to seven (7.0) gpm for passenger vehicles
F. 1987
1. November
a. The EPA relaxed unburned gasoline fumes standards in exchange for vehicle fleets to be converted to cleaner burning fuels
2. December
a. Congress voted to extend the Clean Air Act into August 1988
G. 1989
1. 1989 June
a. Pres. George Bush Sr. (REP) called for a greater push for “cleaner” fuels such as methanol, he promised that by the year 2000, half of all American cars would run on methanol
2. 1989 July
a. Being a republican, it wasn’t long before Bush Sr. changed his standings.
b. Bush Sr. now allowed auto manufacturers to “average out” emission testing results, which made it easier to meet the standards
3. Mid 1989
a. ARCO released a new gasoline formula that lowered NOx emissions by five (5) percent, CO emissions by nine (9) percent, and Sulfur Dioxide (SO2) emissions by eighty (80) percent in older cars
b. ARCO announces a new formula that would further reduce smog causing pollutants by thirty-seven (37) percent
c. Bush Sr. proposed another new idea, the introduction of one million (1000000) “clean” cars by the year 1997
-that plan later succumbed to Capitol Hill naysayers John Dingell (DEM) and Norman Lent (REP) 1990
H. 1990
a. On April Fourth (4) the 1990 version of the Clean Air Act was passed
b. This established new standards known as “Teir 1” standards
-they required NOx’s to be reduced sixty (60) percent and Hydrocarbons be reduced forty (40) percent
I. 1995
1. predictions were made that by the year 2015 cars would get fifty-eight (58) mpg if a new greenhouse preperation plan was passed
a. this plan was forgotten during a period of “antiregulatory” feelings in National Policy
2. though it had not been used in new cars since the mid 1970’s, and would not work with new emission controls, leaded gasoline had technically remained legal until 1995
a. older cars that use leaded gasoline, and have not been converted, that grandfather this law are allowed to have lead additives inserted into the gas, if the owner can prove that a conversion to unleaded would lower the vehicles “collectors value”
J. 1996-2005
1. no major changes made" (Taken from outline by Scott Nadvornick written 5/2/05)

 

Well, I'm not going to pick it apart line by line, but you needn't slam a political party here.

But the most glaring error is about PCV and air injection. PCV's were the first smog item starting in 1963 or '64. Air injection started not long after, certainly much earlier than cats and long before 1972. Note 1968 289 heads, often discussed in the small block forums, have a hump in the exhaust port because of the air injection.

PCV wasn't new in '63 either. My dad had a 1952 GMC military truck with a PCV. It was part of the sealed crankcase/ignition/everything else set up required for the truck to meet military fording specs.

 

They started as early as 1975, but was made into law in 1976.

www.accperformance.com

 

Yes while there may have been systems incorporated prior to 1976, they were not legally required on passenger vehicles until that point in time.

And i dont slam any political party in there, rather i slam polititians in general.

EDIT: oops i do take a shot at republicans...thats ok i support whatever is best for my country at the time.

 

EGR systems do not recirculate the exhaust gases for the purpose of reburning the mixture. The actual function of the EGR system is to introduce inert gases to dilute the mixture without changing the oxygen to fuel ratio. The reason you would want to do this is for reducing combustion temperature. Any reburning that happens is simply a nice coincidence. EGR helps greatly to reduce NOX emissions and prevents detonation, which in turn prevents engine damage and increases power. This is some ways may seem counter intuitive, but if the combustion get hot enough to form NOX, then valuable oxygen is used to form a useless compound, effectively robbing power and wasting fuel. By limiting the temperature of the burn, the maximum potential of the fuel can be realized.

 

Excellent - and I truly mean this as a compliment, you are one of the few on here that understands the true purpose of the EGR and how it works.

Good Job! David

 

EGR does not increase power, although it's a better explanation than most I've seen on this site. The formation of NOx emissions does not take away any oxygen needed in the combustion chemical reaction.

From a power and performance standpoint EGR is not a good thing (it lowers volumetric efficiency for one, and how many racecars have EGR systems?), but from the emissions and fuel economy standpoint of a street engine, it is a very good thing.

The internal combustion engine is a heat engine, so more heat energy means more useful work out of the engine. This is why the manufacturers program the EGR to be closed at wide open throttle--to maximize performance where it counts, but still reduce NOx emissions and increase fuel economy at part throttle where most driving takes place.

 

Great post.

 

I wouldn't classify a PCV system as a smog item. Sure it dealt with combustion gases but it made the engine last longer and run cleaner by not allowing the contaminants to turn the oil into sludge.

As far as the air pump reference on the SBF heads. I have some 1974 cast D0OE 351W heads with the bump and they are NOT drilled for air injection.