1975 Air Pump

[Bill H.]

Have converted my 75 Vette to dual exhaust. How important would it be to reinstall the air pump? Just looking to have a nice street ride

Just check the air pump, which I believe is original, since I purchased the vehicle from the original owner . Pump # 781787

[Tom R.]

Re: 1975 Air Pump

Your query did not operationally define what a "nice street ride" means to you but assuming the dual exhaust removed the catalytic converter, I believe the effect is the following. The effect of A.I.R is to introduce oxygen into the exhaust to further complete the exhaust combustion process while the catalytic converter further reduces, or catalyzes NO2 emissions with the pellets in it. Your nice ride has now re-introduced nitrous oxides into the exhaust and the environment. The immediate effect of your nice ride now includes smelly exhaust. The pump no longer has a function with the configuration of dual exhaust without the catalytic converter.

[Keith K.]

Re: 1975 Air Pump

Most 1973 & 1974 cars have an A.I.R pump which pumps fresh air into the exhaust manifolds (fittings in 4 holes on each manifold). If the A.I.R. pump is removed, these holes need to be plugged. 1975 & 1976 cars equipped with A.I.R. use a single manifold tree that bypasses the exhaust manifold and connects to the right-side exhaust pipe. Certain 1977 cars if equipped with A.I.R. again have the 4 holes in each exhaust manifold.

Depending where you live, some states require periodic inspections / smog testing even on older cars. Check your local rules.

[Joe L.]

Re: 1975 Air Pump

Your query did not operationally define what a "nice street ride" means to you but assuming the dual exhaust removed the catalytic converter, I believe the effect is the following. The effect of A.I.R is to introduce oxygen into the exhaust to further complete the exhaust combustion process while the catalytic converter further reduces, or catalyzes NO2 emissions with the pellets in it. Your nice ride has now re-introduced nitrous oxides into the exhaust and the environment. The immediate effect of your nice ride now includes smelly exhaust. The pump no longer has a function with the configuration of dual exhaust without the catalytic converter.

Tom------

I actually had an experience with this years ago. I was out driving my original owner 1969 Corvette convertible one day and the AIR pump seized and the belt broke. I noticed that I was thereafter experiencing much more fumes in the passenger compartment when I was driving, especially with the top down. I replaced the pump and belt in short order and the fume problem ceased.

For this reason alone, I do not recommend removing or disabling of the AIR system. In addition, our old cars create lots of exhaust emissions due to the primitive technology of days gone by. Let's not make them any worse by removing or disabling the air pollution control systems they did have. The AIR system, in particular, was quite effective in reducing emissions. As a matter of fact, AIR systems are still used to this day for some vehicles. The notion that these systems "rob all kinds of horsepower" is sheer nonsense. The horsepower reduction is actually quite minimal.

[Tom R.]

Re: 1975 Air Pump

For this reason alone, I do not recommend removing or disabling of the AIR system. In addition, our old cars create lots of exhaust emissions due to the primitive technology of days gone by. Let's not make them any worse by removing or disabling the air pollution control systems they did have.

Yes Joe! One can always tell when the post-1970 emission control devices have been disabled...in fact one can tell when pre-1970 emission-less vehicles are close by. The fumes are borderline nauseating. The obvious venues are the NCRS indoors meets.