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Discussion Starter #1
My car is a 66 Lemans with a 455 out of a 73 Grand Safari Wagon. When I bought the car ir came with new chrome valves covers after driving the car for the past 3 years I decided to chrome up the engine a little. Put the new valve covers on now I would like to replace the stock air cleaner assembly with a chrome one.
On the stock air cleaner there is a hole for a pipe that sticks up on the front the Qjet carb. On the aftermarket air cleaners that I have seen locally they do not have that hole in the base assembly.
Does a guy hack up a brand new base assembly trying to drill a hole in it or can a guy get the proper fitting aftermarket chrome air cleaner assembly?
Any help on this issue would be appeciated. Thanks, from the Great White North.
 

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64-67 Expert
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I've personally never had very good luck with just bolting on any aftermarket part without modification, weather it's a throttle cable, a set of headers, or a window crank handle. How about locating an original base, and use the new chrome top section?
 

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Trying to visualize for sure what you're talking about... does the air cleaner on it now have some sort of hose/pipe connecting to the side of it with the other end connecting to the carb, or is this "pipe" something that's a cast-in part of the top of the carburetor body and the hole in your current air cleaner just fits over it? Is the problem because this "pipe" doesn't let your new air cleaner sit flat on the carb?

(A photo of the carb and the part you're talking about would help greatly).

If it's the latter - the pipe is part of the carb body, then is it "inside" the ring on top of the carb where the round air cleaner gasket sits, or is it "outside"? In either case... if the pipe is part of the carb body then it's probably a fuel bowl vent and needs to "see" air for the carb to work. If the pipe is "inside" the gasket ring then the vent is designed and calibrated to see filtered air. In this case I'd drill a hole in the air cleaner for it to fit through and also make some sort of rubber seal to fit tight around it when the air cleaner base is on - otherwise you'll be leaking unfiltered air into your engine and that's not good. If it sits "outside" the gasket ring, then the easier solution is to use a spacer to lift the air cleaner up enough to clear. If other clearance issues prevent you from using an air cleaner spacer ring to just lift up the air cleaner enough to clear the "pipe", then you're probably going to have to modify the air cleaner. I had to do something like that to the air cleaner I'm using on my car. If that's your situation, let me know and I'll show you what I did.

If the whole thing is in fact some sort of hose/line, then it's probably either the connection for the PCV or a temperature sensor/switch that controls a vacuum source, and none of the above applies :D And I'll start over... :rofl:

Bear
 

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The nipple sticking up out of the carb is the stock Q-Jet bowl vent that was used only by Pontiac on all 1971+ Q-Jets. Since nobody is going to make an aftermarket air cleaner base specifically for 1971-1979 Pontiac Q-Jets, the answer is, yes, you drill a hole in your aftermarket base to make it fit. No problem. The other alternative, as stated above, is to use your stock air cleaner base with the aftermarket filter and filter top.

The other thing you're going to have to do with an open-element aftermarket air filter is to get a valve cover breather for the passenger side valve cover - there won't be any way to use the stock breather tube that goes up to the side of the stock air cleaner housing. You have to have some breathing capability on that valve cover to keep the PCV system correctly operational.

Lars
 

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Discussion Starter #5
Thank's for the information. It appears as though I will have to drill a hole in an aftermarket air cleaner assembly if I decide to go that way.

The tube sticking up off the carb does come up inside the air cleaner assembly, inside the air filter. (i was unable to post pics?)

Is there any benefit performance wise to having an open air filter as opposed to stock?

Thanks again for the assisstance
 

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Let me verify something... the key question is not whether the tube sticks up inside the air filter - the question is whether or not the tube sticks up inside or outside the air cleaner GASKET on top of the carb. There were several different QJet tops with different sizes and locations of vents. If the vent on yours was designed to "see" air at normal atmospheric pressure (it's "outside" the gasket sealing ring), then drilling a hole inside the air filter where it will be exposed to the partial vacuum inside the filter will most certainly upset your carb calibration and have you chasing mixture/delivery problems that won't seem to make sense. If that's the case, what you have to do is create a dimple on the underside of the air cleaner base so that the vent can "see" outside air without getting in the way of the air cleaner, and also without creating a leak that lets un-filtered air into your engine.

I had that problem on my 69, running a 455 SD Qjet (with a HUGE vent tube) under a factory ram air pan. What I did was cut a hole in the pan to clear the vent, then I cut the end out of an empty CO2 cartridge and welded it on top of the hole - thus creating clearance for the tube to get air, yet maintaining the air filter integrity.





Bear
 

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Bear, that's impressive! Very well put,and that's doing the job the right way. A carb vent and venturi are definitely two different things!!!
 
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