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Holley Valve Cover Adapter Question

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Old Aug 20, 2025 | 10:37 AM
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Default Holley Valve Cover Adapter Question

I have a set of Holley LS to SBC valve cover adapters that I am trying to get to work on my engine. Basically these are regular valve covers with bolt holes that allow you to install SBC covers over them, concealing the wires/coils/etc. The problem I am running into is the breather hoses. These originally came with tiny metal baffles that install over the breather holes so that it meters the air coming out of the breather and won't spit out oil on acceleration and high rpm driving. I can't seem to find these baffles - I imagine I tossed them because I was originally running a pcv setup and used a cheap pcv valve, but with my new build, I am running a breather off each valve cover to a catch can. So, I need these baffles.

The baffles seem pretty simple to make, as they are just small plates that screw to the inside of the cover. However, I believe they are bent a little bit so that air is able to escape and it is not complely blocked. I am trying to figure out how much air needs to be able to exit out of here. Has anyone made these baffles before or come up with something else?

Link to the valve covers below. If you go to the hardware photos, you can see the baffles in the bottom right of the photo.

https://www.holley.com/products/engi.../parts/241-296

Instructions

https://documents.holley.com/df0c283...ba202458a5.pdf
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Old Aug 21, 2025 | 04:29 PM
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Old Aug 28, 2025 | 07:28 AM
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In the instructions you linked, those are called "PCV Baffle Block-Off Plates." I'd call Holley and ask if they are meant to be baffles or block-off plates.
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