Air Cleaner Ring

[Todd L.]

for the 73 -74 Air cleaner ring on BB's, I know the BB has an elliptical shape to it, but is there a difference in the number of notches 3 versus 4? I am having a difficult time finding the correct ring, I have a catalog that advertises a ring with 3 notches and a ring with 4 notches they are both for the 73-74.

Todd

[Harmon C.]

Re: Air Cleaner Ring

The 73 was three notches. 74-75 they added a notch and I would say it is because the location for the vent form the valve cover to air cleaner was changed and the ring was made to fit all air cleaners of the same engine 350 or 454.

[Robert R.]

Re: Air Cleaner Ring

Lyle,

Could you answer another question as to air cleaners?
I remember my first '73 having a black plastic / metal "doodad" attached to the base but inside the the area of the filter. It had a vacum line attached below the base. But my current car has a rivet in it's spot.(My car has the AIR system removed). What was it and is it important with the AIR system gone as well?

BTW - Nice pix on your Avatar.

Bob Ricchio

[Harmon C.]

Re: Air Cleaner Ring

I have never seen the base of a 73 air cleaner with a rivet or a (doodad). The line on an air cleaner is present on later C-3's.

I just found that picture deep inside my computer.

[Robert R.]

Re: Air Cleaner Ring

Lyle,
I may have not explained this well.
My current '73 Air Cleaner Base has a rivet to seal a hole where I remember the earlier '73 I owned had this for lack of knowing what it is / was could be an emission sensor (the "doodad").
I do remember having to disconnect the vacuum line before totaly being able to remove the air cleaner assembly from the carb.

Any idea as to what I am refering to?

Bob

[David M.]

Re: Air Cleaner Ring

I believe you are referring to the Thermac control switch. It thermostatically controls/actuates the flapper valve in the snorkel to allow cooler air in. Its part of the emission system on 70-80s GMs

[Michael W.]

Re: Air Cleaner Ring

Lyle,
I may have not explained this well.
My current '73 Air Cleaner Base has a rivet to seal a hole where I remember the earlier '73 I owned had this for lack of knowing what it is / was could be an emission sensor (the "doodad").
I do remember having to disconnect the vacuum line before totaly being able to remove the air cleaner assembly from the carb.

Any idea as to what I am refering to?

Bob

Bob,

I know exactly what you are referring to, but have never seen one on a '73 Corvette. I believe Lyle is saying the same thing.

[Harmon C.]

Re: Air Cleaner Ring

The hose to the air cleaner started in 1976 MY.

[Robert R.]

Re: Air Cleaner Ring

OK, maybe my memory might be a bit faded on this one.
What made me ask is the fact that there were some things done to my current car that made me think that something else was missing.

As to David's suggestion, that switch he refers to would be on the snorkel. Where the rivet plug on my air cleaner base is on the flat part of the base within the area of the air filter. The part I remember would be the size of a "quarter".

I will look through some of my books and if I find I picture, I will forward for you.

Bob

[Robert R.]

Re: Air Cleaner Ring

Looking at the Vette Vues 73-77 Fact Book, on page 135. there is a picture of a '77 air cleaner base that shows what I was asking about. On the snorkel is the switch that David suggested, but the part I am refering to for the '73 air cleaner is also shown. It is attached to the base, between the hole for the carb and the air filter, and near the crankcase filter.
Did not that piece have a vacum line from outside the base?
BTW -just what does that "doodad" do?

Bob

[John H.]

Re: Air Cleaner Ring

Looking at the Vette Vues 73-77 Fact Book, on page 135. there is a picture of a '77 air cleaner base that shows what I was asking about. On the snorkel is the switch that David suggested, but the part I am refering to for the '73 air cleaner is also shown. It is attached to the base, between the hole for the carb and the air filter, and near the crankcase filter.
Did not that piece have a vacum line from outside the base?
BTW -just what does that "doodad" do?

Bob

If I understand the device you're talking about, it's a thermal vacuum switch, exposed to incoming air, and if it's below a given temperature, it opens the vacuum supply to the Thermac air valve in the snorkel, which opens so the snorkel draws air from the heat stove on the exhaust manifold. If the incoming air is above that given temperature, it shuts off the vacuum supply, the snorkel valve closes, and the snorkel draws ambient air; that's the way it worked on passenger cars.

[Robert R.]

Re: Air Cleaner Ring

John,
I agree that what you and David described is the Thermal Air valve / switch in the snorkel of later air cleaner bases. What I am trying to figure out is the smaller device inside the base.
By any chance, do you have access to the Vette Vues Book that shows the air cleaner?

Bob

[Michael W.]

Re: Air Cleaner Ring

I just looked at my copy of the book you mention.

The device in the picture you are curious about is the sensor (switch) John H has described. It activates the diverter valve inside the snorkel.

One more time (with feeling) there is no such animal on an original '73 Corvette air cleaner.

[Robert R.]

Re: Air Cleaner Ring

Mike,
It's not the switch in the snorkel that I am referring to, it is the part next to the air filter within the base.

Bob

[Michael W.]

Re: Air Cleaner Ring

Mike,
It's not the switch in the snorkel that I am referring to, it is the part next to the air filter within the base.

Bob

Yes, me too. The part next to the air filter is the switch.