 PCV (breather valve) Vacuum hose connection |
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| Montreal914 |
 Apr 23 2020, 11:55 PM
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#1
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Advanced Member  Group: Members Posts: 2,072 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California 
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Is there a reason why I see a lot of engines (2 liter) where the vacuum hose connected to the PCV, by the oil filler, is connected to the air cleaner box whereas in the diagram, it is clearly connected to the plenum? (IMG:style_emoticons/default/confused24.gif)
My guess is that if the PCV ever gets faulty, there will be a vacuum leak in the intake revving up the engine. Commonly seen (picture from a Google search):  Versus Dave's diagram:  |
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| JOEPROPER |
Apr 24 2020, 06:21 AM
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#2
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The answer is "no" unless you ask... Group: Members Posts: 1,209 Joined: 21-November 15 From: White Plains New York Member No.: 19,387 Region Association: North East States
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I think the picture is how late model '75 + '76 is routed, but think it shows earlier... Not 100% sure. I see the an elbow at the intake that is used on earlier cars.(IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/popcorn[1].gif)
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| Bleyseng |
Apr 24 2020, 11:04 AM
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#3
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Aircooled Baby! Group: Members Posts: 13,037 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
The PCV hose gets connected to the branched elbow for manifold vacuum not to the air cleaner ports. That pic is just wrong as even the hose is the wrong kind.
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| 914werke |
Apr 24 2020, 11:55 AM
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#4
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"I got blisters on me fingers" Group: Members Posts: 11,606 Joined: 22-March 03 From: USofA Member No.: 453 Region Association: Pacific Northwest
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there is no PVC valve on late 75/76 cars
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| Bleyseng |
Apr 24 2020, 01:22 PM
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#5
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Aircooled Baby! Group: Members Posts: 13,037 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Its hard to tell what year setup he is running but as noted there is the 74 stacked elbow on the intake plenum so I assume that is what he is running. but who knows (IMG:style_emoticons/default/confused24.gif)
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| JeffBowlsby |
Apr 24 2020, 02:01 PM
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#6
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914 Wiring Harnesses & Beekeeper Group: Members Posts: 9,222 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None
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Oil vapor blow-by piped into the air cleaner pre-filter as shown, would eventually saturate the filter.
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| Montreal914 |
Apr 24 2020, 02:01 PM
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#7
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Advanced Member Group: Members Posts: 2,072 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California
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It was a 2 liter in a 73 then bumped up to 2056 d-Jet. Now I am converting it to Microsquirt. The PCV is on the oil filler block and I am in the process of connecting the few vacuum hoses needed for the new setup.
I am trying to understand the reason for the case breathing to be connected to the plenum vs the air filter box. Seems to me it increases the potential leaks of the induction setup. If there is no good reasons to pull vacuum in the block, I would rather connect it to the air box. But since it was designed like that, I am sure there is a reason... Would like to know it. (IMG:style_emoticons/default/beerchug.gif) |
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| Montreal914 |
Apr 24 2020, 02:03 PM
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#8
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Advanced Member Group: Members Posts: 2,072 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California
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QUOTE(JeffBowlsby @ Apr 24 2020, 01:01 PM)  Oil vapor blow-by piped into the air cleaner pre-filter as shown, would eventually saturate the filter. Makes sense! Thank you for the explanation. (IMG:style_emoticons/default/first.gif) |
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| southernmost914 |
Jun 5 2020, 12:28 PM
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#9
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KEY WEST/HAVANA Tunnel Authority Group: Members Posts: 338 Joined: 16-October 07 From: Key West/ St. Augie, Fl USA Member No.: 8,234 Region Association: South East States
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QUOTE(Montreal914 @ Apr 24 2020, 04:01 PM) It was a 2 liter in a 73 then bumped up to 2056 d-Jet. Now I am converting it to Microsquirt. The PCV is on the oil filler block and I am in the process of connecting the few vacuum hoses needed for the new setup. I am trying to understand the reason for the case breathing to be connected to the plenum vs the air filter box. Seems to me it increases the potential leaks of the induction setup. If there is no good reasons to pull vacuum in the block, I would rather connect it to the air box. But since it was designed like that, I am sure there is a reason... Would like to know it. (IMG:style_emoticons/default/beerchug.gif) Here ya go. https://members.rennlist.com/pbanders/PCV.htm |
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