This is my Holley carb, missing idle mixture adjustment screw?

It's been missing since i knew about it.

What could this do?

Where do i find a replacement screw?

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'87 D150 Slant-6 A904 with wooden cap

Are you sure it isn't a hex head (allen's wrench) screw buried under where the concealment plug used to be? Mid to late 80s 1945s used hex heads instead of the usual idle mixture screw. The screws were hidden under a concealment plug because only dealers with their special tuning equipment were supposed to adjust the mixture.

Looks like you are also missing the idle stop solenoid that served as the idle speed screw. How do you control your curb idle speed?

I guess i don't have an idle stop solenoid.

I just adjusted the idle speed today using that Phillips head set screw to the left of the part number.

That's a good idea to look for the screw in that hole, if that's what you're saying... i was assuming it would be a screw head outside the carb like in a picture i saw, so i will look tomorrow.



There's a picture i was expecting to find the screw visible, just like the idle adjustment screw that is also there. I have a reman carb installed before i owned the truck, i have now come to realize, so the truck's an 87 but the carb is a baseline Holley 1945 i think with no electronic anything.

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'87 D150 Slant-6 A904 with wooden cap

I looked deeper, got the camera as close as it would fit, see nothing.
I put a hex-head bit in there and felt nothing, though i could try different sizes.

Any guess? Is it missing?

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'87 D150 Slant-6 A904 with wooden cap

I bet the mixture screw is down that hole. The screw itself has a fairly small hex head.

Yes, that is not a 1987 carburetor. I looked closer at the first picture you posted. The idle speed screw is the one closest to the carburetor body. However, it looks like you fast idle screw is bent so that it no longer contacts the fast idle cam. That carb has definitely seen better days.

Yes, Reed, you're right. The screw is in there. I used a mirror to see in there.



Thank you for talking me through this.

By the way, my fast idle screw i contacting the cam very well.

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'87 D150 Slant-6 A904 with wooden cap

I have had so many people ask why I keep a compact in my tool box. I guess no one thinks of the uses of a mirror. I once read a PN using a mirror a magnifying glass and a flashlight.

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