vacuum question
Thread Starter
Instructor
Joined: Jan 2011
Posts: 221
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From: Sylmar CA
vacuum question
On my 77 vette someone unplugged my hose for the vacuum advance. Does anyone know where it goes on the carb or where? From the distributors vacuum advance thing to where? I'm lost on this
Melting Slicks
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From: Texas
Drifting
Joined: Dec 2004
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From: Austin Texas
What kind of carb does your car have? Most carbs have both ported and manifold vacuum ports on them. Ported vacuum ports are going to be higher up on the carb, above the throttle blades, and manifold vacuum ports will be below the throttle blades.
If your car idles good right now and starts ok and depending on what your initial advance is, you may consider connecting the advance to a ported vacuum port. This would leave your idle timing as it is and bring the advance on as you open the throttle.
Is the motor stock or has it been modified?
If your car idles good right now and starts ok and depending on what your initial advance is, you may consider connecting the advance to a ported vacuum port. This would leave your idle timing as it is and bring the advance on as you open the throttle.
Is the motor stock or has it been modified?
Thread Starter
Instructor
Joined: Jan 2011
Posts: 221
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From: Sylmar CA
That picture helps thanks, I'm still a bit lost because my car doesn't have the ac thing or the smog pump. They were removed.
My engine is stock just with different headers but that shouldn't affect anything. I think my carb is a Rochester quadrajet. At least it says that on the carb itself. The vacuum advance for the distributor hasn't been hooked up, I don't know where it goes that's why. I haven't done the timing with the vacuum advance yet either.
My engine is stock just with different headers but that shouldn't affect anything. I think my carb is a Rochester quadrajet. At least it says that on the carb itself. The vacuum advance for the distributor hasn't been hooked up, I don't know where it goes that's why. I haven't done the timing with the vacuum advance yet either.
Thread Starter
Instructor
Joined: Jan 2011
Posts: 221
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From: Sylmar CA
Petes74ttop, that's perfect! I'll try that right now just as soon as I find the hose lol. Any chance on getting a picture of the other side of the carb? I want to see how yours has the hoses hooked up because mine is a mess. Please and thanks.
Thread Starter
Instructor
Joined: Jan 2011
Posts: 221
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From: Sylmar CA
Awesome, thank you petes74ttop. Much appreciated 
Do you know if your vacuum advance hose for the distributor is hooked up to a ported or manifold vacuum source?
And just out of curiosity, what does that hose labeled 'vap can' go to on the far right side of the picture?
Do you know if your vacuum advance hose for the distributor is hooked up to a ported or manifold vacuum source?
And just out of curiosity, what does that hose labeled 'vap can' go to on the far right side of the picture?
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From: mount holly NC
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Hi again,
My vacuum advance is connected to manifold vacuum.
You can test all your ports with a vacuum gauge, with the engine at idle uncap one port at a time and test. If you find a port with no vacuum at idle and good vacuum at 1,200 rpm it is a ported port.
If you find good vacuum at idle and 1,200 rpm you have manifold vacuum.
There is a "Vapor Canister" near the rear of the drivers fender, my car has one hose going to the tank and the other is in the picture.
Hope that helps,
Regards, Pete.
My vacuum advance is connected to manifold vacuum.
You can test all your ports with a vacuum gauge, with the engine at idle uncap one port at a time and test. If you find a port with no vacuum at idle and good vacuum at 1,200 rpm it is a ported port.
If you find good vacuum at idle and 1,200 rpm you have manifold vacuum.
There is a "Vapor Canister" near the rear of the drivers fender, my car has one hose going to the tank and the other is in the picture.
Hope that helps,
Regards, Pete.
