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Passenger side with the questionable hise/pipe. Driver side with PCV hose to the carburetor.
I’m just getting back to my car after a 15 year hiatus, back when I stopped working on it I had just installed a four barrel Edelbrock intake manifold and a four barrel Quadra jet carburetor. I still have the original air cleaner, but clearly that won’t work. My question is this, when I replace the air cleaner what do I do with the vent hose in the passenger valve cover? I know the right valve cover pcv valve connects to the carburetor, couldn’t I just split the hose at the carburetter and connecting the passenger side as well? Or would that not provide enough positive vacuum. Or am I way off base and have no idea what I’m talking about. What is the purpose of venting the valve covers to two different locations. I guess I’m confused because both enter into the air intake regardless.
Question two, the steel pipe that extends from the block to the snorkel and of the air cleaner, what is its purpose and what do I do with it when I replace the breather with one that has no port for it?
Last edited by Darryl-350R; Aug 1, 2019 at 04:47 PM.
The PCV valve is a one-way check valve that draws air from the crankcase into the carburetor to burn the blow-by gases, and the filter on the other valve cover is the inlet for fresh air. So clean (filtered) air is drawn from the air cleaner, through the passengers side valve cover, through the crankcase, out the drivers side valve cover, and into the carburetor.
The large pipe routes heated air to the air cleaner to improve fuel atomization. The exhaust manifold has a shroud around it, which is the heater for the incoming air.
I just put a rubber hose o tn he end of the pass side breather and attached it to the bottom of my open aircleaner base that way it still draws fresh air.
If you are considering an aftermarket open element air cleaner, most of them come with an elbow like this that goes on the underside so you can run a hose from the valve cover breather to the air cleaner. You might also want to get a breather with a hose fitting.
The PCV valve is a one-way check valve that draws air from the crankcase into the carburetor to burn the blow-by gases, and the filter on the other valve cover is the inlet for fresh air. So clean (filtered) air is drawn from the air cleaner, through the passengers side valve cover, through the crankcase, out the drivers side valve cover, and into the carburetor.
The large pipe routes heated air to the air cleaner to improve fuel atomization. The exhaust manifold has a shroud around it, which is the heater for the incoming air.
If the passenger side is intended to draw air in, is it bad that smoke blows out of it while running? Also.. the connection point on the air cleaner is out it’s of the filter. Also again.. if the carburetor is drawing air through the air cleaners snorkel, that puts the while air cleaner in vacuum, so wouldn’t attaching a hose to it draw at rather than feed?
As for the pipe, I knew it had something to do with warming the air on route to the carburetor but u couldn’t remember why. I always thought cold compressed air was better for the overall performance based on how a turbo works.
If the passenger side is intended to draw air in, is it bad that smoke blows out of it while running? Also.. the connection point on the air cleaner is out it’s of the filter. Also again.. if the carburetor is drawing air through the air cleaners snorkel, that puts the while air cleaner in vacuum, so wouldn’t attaching a hose to it draw at rather than feed?
Ventilation air actually flows alternately in and out of the breather, depending on engine speed and throttle opening. At idle and low speeds, engine vacuum creates a suction on the PCV valve that pulls crankcase fumes out through the valve and into the intake to be burned. Under those conditions, the breather on the other side is an air inlet. At idle and low speeds, manifold vacuum is greater than the inlet vacuum in the air cleaner due to the mostly closed throttle blades.
At larger throttle openings, manifold vacuum drops and crankcase blowby pressures will push fumes out the breather. Older cars simply vented this to atmosphere, but it is a hydrocarbon mixture. This is why the closed system first used in 1967 on Calif cars routes that breather flow back to the air cleaner. The inlet vacuum is sufficient to pull those fumes in at larger throttle openings.
Ventilation air actually flows alternately in and out of the breather, depending on engine speed and throttle opening. At idle and low speeds, engine vacuum creates a suction on the PCV valve that pulls crankcase fumes out through the valve and into the intake to be burned. Under those conditions, the breather on the other side is an air inlet. At idle and low speeds, manifold vacuum is greater than the inlet vacuum in the air cleaner due to the mostly closed throttle blades.
At larger throttle openings, manifold vacuum drops and crankcase blowby pressures will push fumes out the breather. Older cars simply vented this to atmosphere, but it is a hydrocarbon mixture. This is why the closed system first used in 1967 on Calif cars routes that breather flow back to the air cleaner. The inlet vacuum is sufficient to pull those fumes in at larger throttle openings.
Interesting... so basically the bottom line is make sure it’s connected to the breather. What about the steel hose, find a way to connect it to the breather as well or is that something that is left off at this stage?
Interesting... so basically the bottom line is make sure it’s connected to the breather. What about the steel hose, find a way to connect it to the breather as well or is that something that is left off at this stage?
"Steel hose"???
Are you talking about the tube on the breather or the metal hot air pipe coming up from the exhaust manifold? The tube on the breather gets replaced by a hose to the elbow on the underside of the air cleaner. The hot air tube is only used if you have an air cleaner with a snorkel with the vacuum operated flapper. If you are going to an open element air cleaner, just remove the hot air tube - there should be one or two small screws holding it to the sheet metal shroud around the exhaust manifold. The hot air tube is simply intended to provide warm air to let the car warm up more quickly in winter.
Are you talking about the tube on the breather or the metal hot air pipe coming up from the exhaust manifold? The tube on the breather gets replaced by a hose to the elbow on the underside of the air cleaner. The hot air tube is only used if you have an air cleaner with a snorkel with the vacuum operated flapper. If you are going to an open element air cleaner, just remove the hot air tube - there should be one or two small screws holding it to the sheet metal shroud around the exhaust manifold. The hot air tube is simply intended to provide warm air to let the car warm up more quickly in winter.
