Wow, hope you guys can get rid of that dept. I can see laws on the books but enforcement agencies with officers who can randomly pull you over! Then take your car and fine you if you don't comply.........oh wait......sounds like a sister organization of the IRS and healthcare reform......Were not far away from this so vote wisely everyone. Sorry to go political, end of rant

 

This was the official version of what the smog pump did, but it was all BS. It takes higher temperatures and a catalyst to do what they claimed, that's why cats came about. If there was reburning going on in the exhaust, they would have needed shields around them like cats do. The pipes would have been glowing red at idle, and they do/did not. All smog pumps did was pump fresh air in the system to make the emissions look cleaner at the tail pipe.

I know a guy who had a emissions testing company that checked power plants, chemical plants, refineries, etc... They were lowering emissions coming out their stacks by pumping in steam. Same principle as the smog pump, just diluting the emissions to make it look cleaner. Did absolutely nothing to actually clean up emissions.

 

I removed my smog pump because it was time. All that I run on the engine that is smog-related is the EFE and PCV systems. Makes good sense to keep those two systems.

As others have stated, with the increased timing advance, there is much less unburnt hydrocarbons leaving the engine. Removing the smog pump makes for much less clutter and I can actually SEE more of what is important (to me): THE ENGINE.

The pump, hoses and brackets are boxed in my garage like all of my other take-offs (save for the 2-into-1 exhaust and 3-way cat... I ditched those after a couple house moves).

My next set of coated Hedmann Jet-Hot headers will be without the A.I.R. pipes. Hopefully, they will bolt in place of my 14 year old Jet-Hot coated full-length Hedmanns.

I will probably install those when I rehab my short block this Fall (bore-rings-rotating assembly).

 

simple cuz it looks like sheet.

 

I believe we're basically on the same page but perhaps just a disagreement/difference in degrees. I recall that there were limits in the adjustments of carbs back then, but it seems to me that it was an attempt to keep the carb from being adjusted too far rich from stoichiometric, not keeping the carb on the lean side of stoich. I don't recall, and please correct me if my memory is incorrect, GM running any carbs on the lean side, as lean drivability with a carb is generally very poor due to the wet flow variations to each cylinder through the intake manifold.

 

I disagree for several reasons, but I welcome any supporting evidence to the contrary.

If the AIR pump was there to merely dilute the contents of the exhaust flow, why did GM go to the extra expense of drilling and tapping the exhaust manifold (eight times on our Corvettes) and the fabricated air manifold to inject the pumped air directly into the exhaust port? For pure dilution purposes it would have been much easier and cheaper (key items in any of GMs decisions back then and now) to simply run a hose from the AIR pump to each exhaust downpipe.
Additionally, if pure dilution was the reason, what was the purpose of reducing the ignition advance (retarding) (Possibly reducing NOx, but the compression ratios had already been lowered, which reduced peak combustion temps and NOx production)? It would have made more sense to keep the timing sufficiently advanced for not only drivability and fuel economy, but customer satisfaction. But GM didn't.
We both agree that catalysts are more efficient at converting/oxidizing the exhaust emissions, but catalytic converters weren't production ready in the early 70's, so that wasn't an engineering option.
What does make sense to me is that retarding the timing does increase the temperature of the exhaust gas at the later stage when the exhaust valve opens. Also making sense is placing the injected air tubing right at the exhaust valve, allowing atmospheric oxygen to contact the exhaust gas when it is at its hottest available point (rather than downstream when it would have cooled a bit). This makes sense why GM would spend the manufacturing money to plumb the air tubes and drill/tap the exhaust manifolds.
I don't subscribe to the concern that the exhaust pipes would glow red. Those engines were not running so rich that there was great quantities of raw fuel in the exhaust just looking for some oxygen to allow secondary combustion.
Regarding the enthalpy/energy change going from CO to CO2, chemistry class was a long time ago, so I'm a bit rusty there.

As I mentioned above, I welcome any data or information that will change my mind. I don't make any royalty money off the old systems, so I don't have any vested interest in maintaining my viewpoint if I'm wrong.

 

I too think we are saying the same thing: The limiter caps on the idle mixture screws were indeed to prevent the carb from running too rich or richer from the leaner position set by GM for emissions. My Original Qjet as well as the Holley 4175 Qjet replacement I put on my L-82 in 1985 both had limiter screws. The L-82 with all emissions gear was a notorious poor idling engine and once the limiter screws were removed, the engine idled beautifully-it was amazing. All done to meet the emissions test!

I have been saying for years that once all the emissions gear is removed, timing set correctly, parts verified personally during my L-82 rebuild, as well as my L-82 Dyno numbers on a free breathing L-82, The 73-80 L-82 for the most part is VERY SIMILAR to the 71 LT-1 (330 Gross HP)-pretty much the same engine. The 70 LT-1 (370 Gross HP) was different with a solid lifter cam and 11:1 compression but just that 1 year.

 

It may be that GM was blowing fresh cool air on the exhaust valves in an attempt to cool them and prevent failure because of the lean mixtures with retarded ignition timing and at the same time dilute the emissions.

 

except the air was pumped in downstream of the valves. i think they put those tubes where they did for packaging. nearly every small block used the same or similar exhaust manifold and the components would already be packaged with the engine , and when the exhaust was hooked up there wouldn't be anymore components or hook ups necessary . but i agree it was a poor way to do things. this is what happens when environazis and lawyers play engineer.

 

If a government official pulled me over and started pulling hoses off under the hood of my 40 year old car I would have a big problem with it.

 

Oh, yeah? What would you do about it? What could you do about it?

I'm not trying to be a jerk here, mako, I feel exactly the same way you do, just saying....what could you do about it? Complain to somebody? Who? I sure don't know....a lawsuit, maybe? The whole thing gets crazier and crazier the harder you look at it. I guess my real point here is that if a government official ever pulls you over and starts pulling hoses off under your hood, he/she will have every "right" to do so, and you will be committing a crime if you try to stop him/her.

Oh, well, enjoy these old bones while we can, that's what I say.

Scott

 

The clock is ticking on our whole hobby. When you have a government which believe in and is supported by the younger generation that global warming is real, and willing to shut down the entire coal industry, no matter the cost, you can be assured that our little tiny world of classic cars can be wiped out with the stroke of a pen. Even if it is not logical, or makes any sense, it will not matter. Even if our cars produce no dangerous emissions of any significance, it will not matter. The government is here it save us all!!! So much for freedom.

 

Is the sky falling and I missed it?

 

I have lived in CA since 1967. I believe we have the strictist pollution laws in the country. I have never heard of a government official pulling someone over, opening their hood and start pulling hoses. Years ago I swapped out the Hooker side exhaust for the GM side exhaust and set the timing at 4* for the bi-annual test. Passed every time, went home and reversed the procedure. Of course 74 and older are now exempt. No big deal. Nowadays the biggest cheaters are the Honda guys replacing cats with straight tubes.

 

It's a Canadian thing.

 

Mike,

I ran this test on a 1970 LT-1 years ago... Just because I wanted to know (and the engine was out of the car). The engine lost 3 horsepower with the pump hooked up compared to not operating. Your source was 1 horsepower. Any way you want to look at it, the actual loss is minimal.

If you're looking to gain lots of power by removing the A.I.R. pump, you might want to look elsewhere.

Regards,

Stan Falenski

 

I actually had mine cosmetically restored, disabled and put back on because of how much I like the way it looks!

 

be patient, it will get here.

 

I was quoted my numbers by John H.

 

Its a Canadian thing for now! Haven't you been watching the news? If the American government is willing to shut down coal plants and putting vast quantities of people out of work, you don't think that emission testing etc will return to the auto industry?? Wow! Remember, according to the libs, the sky is falling.