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I have an Edelbrock manifold and Holly carb on my 68RS 4spd, and not enough vacuum ports for the RS system, PCV and power brakes. Vacuum ports include the PCV port at the back of the carb, and a single port from the manifold, provided thru the low-profile fitting Edelbrock sells. Two questions:

- Can I tap the hose to the PCV for either brake or RS vacuum?

- How have others addressed this combination?

Thanks in advance for any help.

Marc
 

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Marc, the factory used the manifold port for the brake booster, the trans (auto) and the RS headlight doors. The PCV was a seperate port in the base of the carb. Use the single port off the manifold for your booster and tap into it for your headlight door system. Use the big port on the carb for the PCV. Your carb should have 2 small vacuum ports, one above the base plate (ported) and one in the base plate (manifold). Use one of them for your vacuum advance...
 

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as long as you put the correct filter looking thing inline with the brake booster, i can't see why it would be a problem. GM actually ran the brake booster off the PCV valve circuit on some of their cars over the years.
 

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If it's the same in-line filter that's on my Vette, I don't think it would prevent blow-by gases from entering the booster when the engine is shut down, etc. It's more of a filter that prevents junk from being sucked into the engine from the maze of vacuum hoses and components (headlights, etc.) that use vacuum.

What he needs is some sort of inline valve that shuts off the hose to the booster when no vacuum is present.

Is there such a thing?
 

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I had the same dilemma.

Just install a "T" fitting on the intake and you can hook up the RS lights and the transmission. Works perfect and cost about $7.00 from home depot.

I painted it cast blast silver and clear coated it--it looks great, declutters my intake and delivers full vacuum to both.

The power brakes should go to the back of your carb. The PCV to the front.
 

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If it's the same in-line filter that's on my Vette, I don't think it would prevent blow-by gases from entering the booster when the engine is shut down, etc. It's more of a filter that prevents junk from being sucked into the engine from the maze of vacuum hoses and components (headlights, etc.) that use vacuum.

What he needs is some sort of inline valve that shuts off the hose to the booster when no vacuum is present.

Is there such a thing?
the one i'm talking about looks like a black plastic fuel filter with one fitting coming in at a 90 degree angle- it is plumbed right inline between the booster and engine, no other hoses are hooked to it.. it's sole purpose is to keep vapors out of the booster when the car is shut off to keep them from eating away the diaphragm.. pretty much every GM car and truck with vacuum power brakes built from the early 70's to the 90's had this valve on it from the factory.
 
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