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OK, so I took my '81 in to be smog checked yesterday and for the first time in the decade I've owned it, it failed to pass. No problems with tailpipe emissions, but it flunked the visual inspection due to this disconnected fitting:
It lines up (roughly) with an opening in the lower air cleaner housing, but I have no idea what it should be connected to . . . something along the lines of a crankcase vent filter perhaps?
Yup. That hose feeds air to each tubular exhaust manifold on both engine banks. Looks like someone cut the line. Does the car have stock exhaust manifolds ( with plugs in the air pump openings now) or headers?
Uh yeah, I know it's the AIR pump. What I didn't know was what the odd looking hose/elbow/clamp fitting is and what it connects to.
After a lot of investigation, it appears that this:
was the OEM hose that connects the AIR control valve to the opening in the air cleaner housing. Like So:
GM no longer produces this part, and evidently no aftermarket supplier does either. The only ones I could come across were NOS, and they run north of $125
I suspect the original hose cracked or became damaged and a previous owner way back when fashioned the jury-rigged thing that's on the car now. Unless I can find a junk yard hose or $10 new aftermarket one somewhere, I think I'm just going to slap a vent filter in the AC hole and run a hose from its nipple to the plastic elbow on the existing fitting. As long as the connection is solid and doesn't move, it will hopefully pass the visual smog inspection.
If the hose on your first pic is the INTAKE of the air pump you are right, this should be connected to the inside of the air cleaner. Earlyer air pumps hat a separate air cleaner mounted on them. But a hose to the big cleaner is cheaper in production
That is sometimes referred to as the bypass. At certain times air is not pumped into the exhaust so it is bypassed to the atmosphere.Running the hose to the air cleaner is just quieter otherwise, the way it is, does not change it's function.
Looking at your carb, I can tell you that the o-rings on your idle air bleed are bad as someone has screwed it all the way down to try and enrichen the idle circuit.