The Stovebolt Site Forums The Shop Area Engine Shop Where do I pick up vacuum ?

I think the engine was changed sometime prior to my purchasing this 1953 Suburban. I have no vacuum to run my wiper motor or the vacuum advance. Can someone tell me what is needed to get these items working? I have included a photo of the base of the carb. to show what I have.
[img]http://community.webshots.com/s/image16/2/21/93/183822193ESnrjN_ph.jpg[/img] Thanks in advance for the help

All I'm seeing is a red "X", so your picture host must not be working right. The vacuum needs to come from below the throttle plates, like from a fitting in the manifold, not the carburetor, or a large-diameter fitting at the base of the carb that enters below the throttle plate. If there's a threaded hole with a pipe plug in it somewhere in the manifold, that would be the best location to put a vacuum nipple.
Jerry

It looks like someone tried to make a PVC by sucking fumes out of the valve cover into the vacuum port.

The fumes should be sucked from the crank case, and a PCV valve should be used. If you have a road draft tube at the crank case, that`s good to go.

Take the brass elbow and connect it to your wipers.

The port at the intake (where the wipers should be connected) delivers most vacuum at idle and almost non at hig rpm. You need high vaccum at high rpm for the spark advance.

So the spark advance must be connectet to the carb.
There is a port at the back (passenger) side.

Hope that helps.

Frank

That is right where you said. I removed the plug and will buy a fitting for the advance.
Can I use 1/4" rubber tubing and press on fittings? There are no connections, lines or tubing of any kind at this point. What do you recommend?
Not sure what this is? I do have an oil cap, that allows positive ventilation. Would I just plug the hole in the valve cover where the fumes are being sucked out? Hotrod and Stovebolt thanks so much for the help.

The road draft tube was used on pre-PCV engines. It's a large diameter tube coming out of the crankcase near the distributor, and turning down into the slipstream below the engine. Above 30 MPH, air passing past the end of the tube creates a vacuum, and draws air out of the crankcase. Slots in the valve cover, or an oil fill cap with a mesh filter allows air to be sucked into the valve cover. The PCV system was used from the late 60's on up, and resulted in a cleaner-running engine because crankcase vapors were drawn into the intake and burned in the cylinders. Engine wear decreases dramatically, since dirt isn't drawn into the engine if the PCV system uses filtered air for ventilation. Your engine can be adapted for positive ventilation pretty easily, but it's frowned upon by the restoration purists.
Jerry

So, you're sayin' you have only one manifold vaccuum port? The one in the pic? There's no threaded plugs anywhere else on the intake? How 'bout just inboard of the carb? Don't know much about 235's or 261's but, I'd think even if the motor was original and without PCV, you'd at least have two vaccuum ports. One for wipers and one for a brake booster if vehicle so equipped (plugged if not).
Did the fuel pumps on old Chevy motors ever supply vaccuum? I think the wipers on my Pontiac are powered from a vaccuum port at the fuel pump.

Muggsy, the pump boosts vacuum, but doesn't supply it. A line runs from the manifold to the pump, and the pump dampens out the fluctuations when the throttle is opened under load. Some applications also had a reserve tank, with a one-way valve to provide a little backup on a long pull. Trucks with the hydrovac brake boosters usually had a big vacuum reservoir for that purpose.
Jerry

any rubber hose that is strong enough not to colapse under vacuum is fine (so don`t buy that fish tank hoses). A usual gas hose for exempel will work great and can resist the heat in the engine compartment.

I think the guys explained the draft tube verry well.

Make sure you get some fresh air to the valve cover.
Take a vented oil cap or - if you fill in the oli at the side of the motor - use something that provides enough air when you plug the hole in the valve cover.

I don't see the plastic insulator between the carb and manifold. It looks like the studs would be too short if you wanted to put one in. Am I blind or is the insulator optional?

I just read your other post - now I see what happened.