327 PCV power brake booster and Edelbrock - Impala Tech
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post #1 of 4 (permalink) Old 05-01-2020, 11:51 PM Thread Starter
Join Date: Sep 2017
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327 PCV power brake booster and Edelbrock

Ok guys I'm in need of help I've GTS a lot and can't find a good link I promise not being lazy. Ok so I have a 64 stock valve covers no holes on them. I just got my power brake booster I know I need vacuum for booster the Edelbrock is 1406 it has a port in the rear closer to the distributor that was plumbed to a ""drift tube"" with a pcv valve on that. I read that that port should go to the brake booster that's easy now my question is and maybe I'm over thinking it but do I take the vacuum port on the front of the carb and plum that to that drift tube it a pcv valve in line? If so how does the block get a intake. I read that normally one valve cover is intake and the other is "exhaust" how do I add my booster vacuum and pcv thank you in advance for any advice and suggestionsAttachment 1Attachment 1Attachment 1Attachment 1
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post #2 of 4 (permalink) Old 05-02-2020, 02:00 PM
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You are confusing Apples with your Chevy oranges.

Valve cover issue and the Positive Crankcase Valve (PCV) can be explained like this: with 1967 engines and down, the engine was vented by a PCV in the sealed oil fill tube and air coming up the former road draft tube via an oil air separator canister in the lifter valley under the manifold. The other end entered either the intake manifold for vacuum or it went to a similar fitting on the base plate of your carburetor. After 1967 you have valve covers with holes in them for a vent tube and the PCV valve.

This where the vacuum for your power assisted brakes and the PCV cross paths. Both use the same manifold pressure: they either share a "T" fitting, or one uses the carb base while the other uses the intake manifold's barbed elbow that threads into a hole in the intake manifold. If you don't have a hole in your intake you can have your machine shop make you one or you can drill and tap it yourself.

You need a one way valve to add to the "T" fitting if you go that route so that the power assist booster always has a full charge of nothing (vacuum) to work with while the engine is off.

Big Dave
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post #3 of 4 (permalink) Old 05-02-2020, 02:18 PM
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My 64 is a bit different, since it has the California mandated "closed positive vent" system (an early form of PCV). So the plumbing is a bit different, but in the stock setup, brake booster vacuum comes from a hole in the intake manifold. And in my case, that hole has a T fitting so it can also provide some vacuum for the A/C (covered in tape in the photo).
The picture from the shop manual (top half) shows the stock routing of the tube from the draft tube hole to the back of the carb. My 64 has the plumbing shown in the lower part.
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1964 Impala 4 door sedan

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post #4 of 4 (permalink) Old 05-03-2020, 12:01 PM Thread Starter
Join Date: Sep 2017
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Perfect thank you guys for the input. I think I got it done I will start draining all my brake fluid in the lines today and start d/c the old lines for replacement
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