Originally Posted by 1957willyman
sorry f-bird88 kinda new to stuff i know when it is idling in shop it makes my eyes burn real bad i heard that a lean mixture can act like a rich mixture i was asking about plugs cause i dont know what are good plugs or good plugs right now iam running NGK
You don't drill the throttle plates unless to get the needed idle RPMs the throttle blades are opened far enough to expose the off idle transfer slot. If that is exposed the idle will be very rich and hard to control. The sole purpose of the drilled hole is to admit enough extra air to allow the primary throttle blades to be set under the idle transfer slot at idle.
There are other ways of getting more idle air into the engine without drilling the butterflies. Most carbs have a stop that ends travel of the secondary butterflies when they are closed. Often this stop is adjustable, usually from beneath with a screw. They can be cracked open just a little without causing secondary fuel metering to start. You can also modify solid stops by drilling and tapping for am adjustment screw, or use a shim attached with some super glue or epoxy.