Idle RPM

[Paul]

With the throttle plates all the way closed, what method is used to adjust the idle speed? Im wondering if its possible to vary the idle while keeping the throttle plates closed.

[Schurkey]

I suppose you could play with idle bypass air passage sizes.  Drill larger until you've got the idle speed you want when warmed up.  If you drill too large, you'll have to re-size the passage back down; and that is possible but not entirely fun.  It's not like fuel injection where there's an idle air control motor and passage.

I suppose you'll have to add some fuel via the idle mixture screw to make up for the lack of transfer slot area at curb idle.

WHY do you want the throttle "all the way closed"?  Seems like you're giving up some transfer slot fuel passage at idle--although you'd gain transfer slot at off-idle.

[Paul]

I was curiouse because theres alot of posts on nozzle drip,  making sure the throttle plates are closed all the way at idle, ported vacume that only gets vacume for the distributor when the throttle is cracked open ect, I rebuilt my carb per recepe #3 and am getting close to firing it up and was just wondering, maybe I need to reread the book.

[Schurkey]

You aren't looking for "all the way closed".

You're looking for "closed enough to prevent nozzle drip".

Easily handled with idle air bypass.  Some applications won't even need that.