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Join Date: Jul 2005
Location: Cleveland, OH
Posts: 1,367
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What is this stuff on case vent?
Came by this pic of a motor and noticed several things connected to the case vent. Any idea what these items might be? I get the throttle actuation bar, but not the item below it or the thing that has rubber coupler to case vent tube.
Last edited by JoeMag; 11-07-2023 at 12:47 PM.. |
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11-07-2023, 12:45 PM
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PCA Member since 1988
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That's weird. The thing on the case vent tube looks like an anti drain-back valve, but if so, it belongs on the return oil hose under the engine. Maybe some kind of PCV setup?
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11-07-2023, 01:20 PM
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The check valve is likely the check valve used on GT3's to build up 10 in Hg of crankcase vacuum.
The thing under the bellcrank looks like a fuel pressure regulator. The thing with the six hoses going to it is likely a vacuum manifold to get a stronger signal for the MAP sensor when running ITB's. No idea what the check valve with the blue top is for, unless it's going to the brake booster. |
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11-07-2023, 01:56 PM
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Thanks Dan... Is this the case check valve? Do you know if it's just a check valve or regulator to 10in vacuum?
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11-08-2023, 06:27 AM
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That's it. It has a spring in it that regulates the crankcase vacuum to 10 in Hg. BUT, do some research on the rear main seal problems and the updates.
In nascar we would run way more crankcase vacuum than 10 in Hg but ran the seals backward so that they would hold the vacuum. Obviously if the dry sump wouldn't pull the vacuum, or blowby went high, it would leak oil like crazy. Later on seals were made that had double lip seals and would hold the oil in under vacuum and pressure. And looking at the 6 hose manifold again, it looks like it might go to the brake booster. Still dunno about the check valve with the blue top. |
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11-08-2023, 08:25 AM
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yea, I've read some update posts on GT3 rear seal issues. Sounds like the last version of air-cooled seal is preferred with the spacer update.
My guess on the blue check valve is for the vacuum canister when using resonance flap (ala: cup intake on top of throttles). Can you run case vacuum at that level on aircooled motor? ...I'd assume GT3 oil pump will pull it down. Last edited by JoeMag; 11-08-2023 at 09:48 AM.. |
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11-08-2023, 09:45 AM
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No reason why it wouldn't work on an air cooled. I know that because of the blowby, it won't work on turbo cars. Not that it will stop functioning, but that the crankcase will never get there under boost.
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11-08-2023, 10:10 AM
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Blue check valve looks like its small for a vacuum hose. Maybe it goes to a vacuum reservoir used to trigger resonance chamber valves. Not uncomment to put resonance intake over ITB's.
https://rasantproducts.com/pages/intake-system-faq john |
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11-08-2023, 01:23 PM
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Location: mt. vernon Wa. USA
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The item below the throttle bar looks like a fuel pressure regulator.
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11-09-2023, 08:06 AM
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