Does anybody have the exact size of the hole in the intake manifold for the PCV provision under the carburetor mount? The manifold that came on my '83 aluminum intake did not have a provision for it, since it used the Holley 1945. Reed drilled a hole in the manifold so the PCV will work with my 1920, but since I have access to any size reamer I want at work, I thought I would ream the hole to the correct size. Thanks.

Hi Eric is the hole in #6 runner?

If so If I may make a suggestion - plug it and dril a hole in the side plenum of the plenum - will help in a way to improve mixture distro - if it is already there - ignore my post

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Fanie Gerber
It's never junk, it's just a part you're not currently using

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Its the hole under where the carburetor mounts, not on any of the runners. Its maybe 3/16 to 1/4 inch, but I would like the exact size.

Pretty sure it's ¼", but it's not critical - the PCV valve is the metering point in the system.

Keep in mind that hole is not used for PCV on carbs made after about '67-'69 (it's in that year range, not sure exactly when). That's when the PCV port was moved over to the inboard side of the BBS and 1920 carburetors, which gave better overall mixture distribution and required no separate pass-thru port in the carb mounting pad on the intake manifold. That pass-thru, however, is used for manifold vacuum to the thermostatic air cleaner on 1920 thru '72, BBS thru '74.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Oh. Well, nevermind then, thanks Dan.

Wait a minute: I thought if one where to put the carburetor gasket on backwards, the PCV would not work, hence the gasket only working one way?

Starting in '73 the (new that year) gasket does not chanellise vacuum to the underside of the carb, and cannot be installed "backward" or "upside down" .

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

For a Holley 1945, yes. That gasket is solid with no hole. For my 1920, the large connection for the pcv hose (on the inboard side) connects to a passageway under the carburetor body that goes to....the hole in the gasket/hole in the manifold. Tomorrow I will flip the gasket to see if the pcv dosn't work (so the hole is covered). There has to be a reason the carb base gasket has forward and top printed on it.

I've taken apart a lot of Holley 1920s, and never seen one like this what you describe. I think if you look closer, you'll see it's not as it first appeared to you.
Yeah, because that directionality is important on pre-'73 carbs.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Well, I stand corrected. Thanks Dan, and thanks for being civil with me.