Chumley

I have seen several '72 air cleaners on Ebay. The round part that fits over the carb is a perfect circle. The '73 air cleaner that is on ny '72 Q-jet has a notch in the front that fits over corresponding part on the carb. I guess the ones on Ebay are for 2 barrel carbs? I know they would not fit without that notch. Chumley

joe_padavano

No, the 2GC 2bbl carbs have a much smaller diameter air horn than the Qjet. The air cleaners with the notch are designed to ensure the snorkel lines up correctly with the heat stove and the fresh air inlet. Also, some of these air cleaner housings have notches for the HEI and need to be properly clocked for that.

Chumley

So the ones without the notch are for engines that did not have the thermostatic controlled air cleaners? My '70 had one, and I thought they were pretty much standard equipment since then.(on taking a second look at mine with the notch, I guess the one without a notch would fit, although it would not be "locked" into place.) Would there really be that much movement if the lid screw were tight enough?
Chumley

joe_padavano

No. What I was trying to say is that as the 70s went on and there was more "stuff" that connected to the air cleaner, it was more important for the air cleaner to be positively located in a specific orientation. The incorporation of HEI distributors in 1973 was probably the event that triggered the notch for clocking, since many of these air cleaners needed a clearance "dent" on the underside to clear the larger distributor cap.