Originally Posted by Dizturbed One
My Air Cleaner does not have the foil duct coming from the exhaust manifold like I've seen on so many other vehicles. The port is there on the air cleaner, and the air cleaner has the flap inside the intake. The flap is hooked up to vacuum via a single port the protrudes from the top of the intake. Also, the manifold does have a heat shield on it, but there is no provision for the foil duct on it, and no duct. I'm almost inclined to believe it never had it, as the last owner claimed it passed smog this way... However, the words of a salesman, if only a salesman for a day, mean little to me.
Is this duct required to pass smog? Is there a way to accommodate the use of one without having to change the heat shield? I would hate to have to search for one at the junkyard and swap it out, would really like to get this thing smogged and in my name tomorrow!
You always have two battles in California; one, will be the equipment that should be there. Two, will be passing the emissions test for gasses present in the exhaust. It is possible to pass the second one with parts missing such as the hot air stove to the air cleaner. On the other hand the tester may look under the hood, see the missing equipment and stop the test right there till you replace the missing equipment. I canít say which you'll encounter, apparently the previous owner got this past the equipment part and it passes the emissions part. You might not get that far if this is a different test station that you're going to.
The hot air inlet off the exhaust into the intake is only there to allow the use of a leaner mixture on cold starting. The dirtiest part of emissions and highest internal wear of engine parts is during the cold start enrichment phase (choke). The hot air stove is only there to reduce the effects and time it takes to transition through cold start. The flapper valve on the air cleaner is both vacuum and thermostatically sprung for control. The thermostatic spring opens the valve when the engine is cold allowing preheated air drawn over the fast to heat exhaust manifold into the carb or TBI. As the engine heats up internally the thermo spring closes the flapper valve so the engine only takes in unheated air for better power output when itís fully warmed up. The vacuum control is to force the flapper valve open if you demand maximum throttle while the engine is still cold, the assumption being this constitutes an emergency need for power where engine life is sacrificed to the greater good, whatever that may be.
Since the smog test isn't usually done on a cold engine, the lack of this device will not affect the gasses in the exhaust. Its absence is, however, an equipment issue; whether they make it so, or not, that I can't answer.