What is this??
Melting Slicks
Joined: May 2019
Posts: 3,150
Likes: 1,366
From: Mid-Atlantic
2025 C4 of the Year Finalist - Unmodified
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Think it's part of the pcv system flow.
I think.
I think.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
You're right...it is. It's for the hose that plugs into the pass/right side of the TB, and runs to the right side valve cover.
Under part throttle, the PCV system is pulling some vacuum...that orifice and the respective hose to the right valve cover provide fresh, filtered make-up air to the "oiled" areas of the engine. Under WOT, where there is no vacuum and probably a good amount of blow by, that right side hose becomes a crank case VENT, vents out the front of the TB and those fumes/vapors are drawn into the engine through the open throttles, and burned.
Under part throttle, the PCV system is pulling some vacuum...that orifice and the respective hose to the right valve cover provide fresh, filtered make-up air to the "oiled" areas of the engine. Under WOT, where there is no vacuum and probably a good amount of blow by, that right side hose becomes a crank case VENT, vents out the front of the TB and those fumes/vapors are drawn into the engine through the open throttles, and burned.
Melting Slicks
Joined: May 2019
Posts: 3,150
Likes: 1,366
From: Mid-Atlantic
2025 C4 of the Year Finalist - Unmodified
2023 C4 of the Year Finalist - Unmodified
2022 C4 of the Year Finalist - Unmodified
2021 C4 of the Year - Unmodified Finalist
Well, there you have it. Looks like Tom expanded on it thoroughly.
Pro
Joined: Aug 2020
Posts: 647
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From: Liliha Bakery stuffing my face with coco puffs!
If you do a search for that particular throttle body and view the accompanying gasket, my vote is that hole serves no purpose. 
BBK 94-96 LT1 Throttle body
BBK 94-96 LT1 Throttle body
Last edited by stew86MCSS396; Sep 10, 2022 at 04:13 AM.
Thread Starter
Burning Brakes
Joined: Jun 2022
Posts: 844
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From: Florida
If you do a search for that particular throttle body and view the accompanying gasket, my vote is that hole serves no purpose.
BBK 94-96 LT1 Throttle body
BBK 94-96 LT1 Throttle body
After looking at the routing more closely, it is definitely related to the vent tube on the passenger side valve cover.
Ric
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
No ****?
