I know that when you have to open the throttle stop for the idle past a certain point on Holleys, you are supposed to drill a hole in the throttle blades. The idea being that it being open to far uncovers something you don't want uncovered at idle...and drilling the holes lets you close them back doan and maintain the same idle speed. But for the life of me I can't remember what it uncovers.

Right now there is a small hole above the plates, and another below. There is also a vertical slot that my plates sit about in the middle of, with at least a 1/8" exposed below the plates.

Do I need to drill holes...and if so..how big? It's a Holley 650 spreadbore DP.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

The slot you are refuring to is called the transfer slot. If you have to open the throddel far enough to uncover this slot fuel will be pulled from the main well, causing a very high idle and a untuneable mixture. Drilling small holes in the throddle plates causes a small vacume leek and alowes the plates to be closed, semi- covering the transfer slotes to retain idle mixture adjustments. This should only be done with high lift cams that produce little vacume. If you have a vacume leek you need to find it first.

 

Ok..so it's the slot that not supposed to be exposed at idle. I couldn't remember. I have a fairly decentlt sized cam..so I don't suspect a vacuum leak.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

Jester,
If you've got at least 1/8" (.125") of the slot exposed,, it's too much. The slot should be exposed between .045 and .060". Have you adjusted the secondary throttle position yet? If you haven't and depending on the size of the cam,, that may get it without you haveing to drill the throttle blades.

 

Thanks BadSS....thats what I wanted to know. It doesn't have a secondary position adjustment, it's not a true double pumper. I built it from a 6210 carb, VS center hung float bowls..and a fair amount of modding.

So I'll drill the plates out. guess I'll start with 1/8".

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports