# 72 350 lemans emission removal



## oskarm (Mar 31, 2019)

Have a 72 350 2bbl auto. How much of the emissions stuff can I remove?


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## O52 (Jan 27, 2019)

The only thing I would remove or bypass would be the temperature controlled spark advance. Can't recall whether the 72s had a transmission controlled spark advance or not. Just run your distributor advance to a good ported vacuum source. 
If the idle bleed screws still have the limiter caps installed (doubtful) remove the caps and readjust the carburetor. 

I would keep the following;
The PCV breather system which is actually beneficial for your engine. 
The fuel evaporative system removes fuel vapor from the air and doesn't affect engine operation if maintained. Keeps the fuel smell to a minimum. 

And don't throw any of it away.


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## PontiacJim (Dec 29, 2012)

oskarm said:


> Have a 72 350 2bbl auto. How much of the emissions stuff can I remove?


How much stuff are you looking at? X2 from above. You should not have very much to remove for 1972.


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## oskarm (Mar 31, 2019)

Thanks for the input. I've attached a photo of how the car was plumbed when I got it. the plastic piece up front is broken, so a line that should go to somewhere is missing. The other tube is plugged as shown in the picture and there is a port coming out to the right side of the carb that is capped. The tube going to the trans is connected to connections at the back of the carb. Thanks for any help.


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## PontiacJim (Dec 29, 2012)

Looks like you have a real project on your hands. *GET* a Service Manual for your car if you plan on working on it yourself. They are easily available online and will give you most everything you need to know about your car.

I don't see a vacuum hose that goes to the power brake booster to the back of the lower carb?

The hole in the valve cover has a tube that connects to the air cleaner housing.

The hose going to the front lower carb and routes to the valley pan is the PCV connection with the PCV valve in the valley pan. Replace all of that to include the rubber grommet in the valley pan to ensure it is working and sealing correctly. Any leak will mean a vacuum leak and then you'll have other tuning issues.

Pull off the round canister/bracket I see on the intake with its short hose and something plugging it. Is there a hose connecting the choke diaphragm found on the side/rear of the carb? If not, I think that hose going to the cannister will get plugged into that diaphragm. If I am not mistaken, you can see the choke is closed which is will be to start the engine, and once the engine fires, engine vacuum is applied to that diaphragm to pull the choke slightly open to allow air in so the engine will run. The choke will then continue to open as the engine heats up and the bi-metal spring at the bottom of the choke rod expands and continues to open the choke to its full open position. If the diaphram is already connected to a vacuum source, simply cap the hose fitting where the hose from the canister connected.

You will need the transmission line connected to the back of the carb which appears to already be there and attached.

I see a fitting/nipple just in front of the carb in the manifold. Use this for the distributor vacuum advance. It is direct manifold vacuum. You can use "ported vacuum" which would be a port coming off the carb somewhere (I don't see it in the photo, but may be on the other side) to connect the distributor vacuum - which is more like factory and will be found in the Servce Manual, but I would use the manifold fitting for now.

On the front left water crossover on the intake manifold I see what should be a temp sensor vacuum tree. Looks to be all busted as it typically has several ports that you would attach assorted vacuum hoses to it. Have no idea that that hose is going to the top of it or where it is connected to? The temp sensor screws into the intake and is sealed, so no water should leak out.

That carb is going to need rebuilding if you plan on using it. I would not use it as is.


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