I have a question concerning the aircleaner on my 69-98. It has those 2 vacuum lines coming out from the little black thing which is marked A/C . Does this mean that it was for air conditioning or to do with the choke? At the end of the air inlet is what I presume to be a valve which draws heat from the exhaust as there is a downtube that attaches to the heatshield and there is a flap inside. This is only going to be a summer car and I was wondering if it is a good idea to just scrap the old breather (rusty chrome) and just put on a new style one without the lines. If so can I just cap off where these lines go or what would be the process?

 

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Originally Posted by wolfman98

I have a question concerning the aircleaner on my 69-98. It has those 2 vacuum lines coming out from the little black thing which is marked A/C . Does this mean that it was for air conditioning or to do with the choke? At the end of the air inlet is what I presume to be a valve which draws heat from the exhaust as there is a downtube that attaches to the heatshield and there is a flap inside. This is only going to be a summer car and I was wondering if it is a good idea to just scrap the old breather (rusty chrome) and just put on a new style one without the lines. If so can I just cap off where these lines go or what would be the process?

Hey Wolfman, in short the original air cleaner is the way to go if you want to remain OEM. AKA, the thermostatic air cleaner, is basically designed to warm the carburetor when the engine is cold so that the choke can open, resulting in better fuel economy. The unit A/C you are referring to is not for air conditioning. The unit is the vacuum diaphragm motor. Inside the snorkel of the air cleaning unit is this motor, which operates a door to allow heat from your original exhaust manifolds to be sucked in to warm up your carb. The catalyst of this unit is the temperature sensor, the green valve inside the air cleaner. One of the 2 vacuum hoses runs from the vacuum (A/C) motor to a port under the temp sensor. The other vacuum hose runs from the temp sensor to a port behind your carburetor. The port looks like a tall skinny nipple . Depending on what sort of distributor set up you have you may have to use an aftermarket air cleaner due to clearance issues or buy a spacer. In closing you don't need the OEM cleaner if you so choose to. If you're using a carb with an electric choke, the choke will automatically open appropriately. If you're using a manual choke, you will have to set it as best you can, however, in my opinion, cold starts aren't the greatest. If you're using headers you won't have to worry about the pre heater port that is found on OEM exhaust manifolds. If you're using stock manifolds then you will have to leave it open or cap it off using plane ingenuity.
Hope this helps.

 

 

That's AC, as in AC Delco, not A/C as in air conditioning.

 

Well I am going to keep the original air cleaner setup as is , except for paint. I sanded and scratched up the chrome as much as possible then used an epoxy resin primer before painting. I will be doing the same to the valve covers. I will be starting putting it back together soon as I would like it on the road by June.

 

That's what I did, I can assure you they will come out nice if you take your time

 

I havebeen posting pics at http://www.flickr.com/photos/wolfman98/ as I go along. The air cleaner and valve covers will be added when I get them done

 

You mentioned that flap inside the downtube, sometimes the get stuck. There is also a valve in the exhaust manifold (driver's side I think) which slowly opens as the manifold heats up (bi-metal spring). Check it too. If it is stuck in the wrong position because of rust/corrosion you will in effect have a clogged exhaust on that side. I only mention this because it happened a few times on cars I have owned in the past. You may be able to work it free with your favorite brand of rust buster, just be sure to apply it on a cold exhaust.

 

Lookin'good wolfman...

 

Yeah like everybody else is saying it's just a IAT (intake air Temp) you really don't need it. It will just help the car warm up faster

 

the flap is insidethe breather , the down tube is hollow and just carries the warm air up to the valve which must open or close the flap. As far as the driver side manifold i did not know about a flap inside it but I know that it has a "pin" that sticks out from it in the center. I do have a good rust buster that I brushed on the outside of the manifolds and also I did the inside of the front bumper with it . Does a real nice job. You can see the difference in the bumper . There are 2 pics before and after though I also painted it with a brilliant silver paint since. I should post a pic of it now. I will check to see if it has a Bi-metal spring and if so will treat it .

 

Do you have an opinion on if I should use manifold gaskets when I put them back on or go without? I did have the exhaust manifolds planed and there is not too much pitting on the heads. I could use some permatex Ultra Gold that I have and go steel to steel or use the manifold gaskets I have (new). It is just that the guy that runs the machine shop ( he is the best engine builder in atlantic canada) says that steel to steel will get rid of heat better than if I use the metal manifold gaskets.