Outer Limits 4x4 Board

Been looking for a while on here and other forums and I can't seem to find much information on tuning the idle on a 300a mixer.

Can anyone breifly run through the procedure? I have it running now but the throttle stop is screwed quite a way in from where it used to be so needs a bit of work!

Also, the idle screw seems quite sensitive. If i just press the screw driver against it, it seems to alter the idle. Is this normal?

I also read the screw that covers the idle screw was just a dust cover but this doesn't seem to be the case when i pulled the inlet pipe off the other day. Does anyone know what size thread it is and is it tapered?

I usually only play with blown systems, and never with the 300A's as they dont work blow through, but with most of the impco stuff the idle mixture is VERY sensitive, 1/30th of a turn can put it out, literally. You shoul dbe able to get it in the ball park, whatever idles smoothest is usually fairly close.

Many remove the standard screw and tap a finer thread, that helps.


Dont worry about the idle too much, as long as cruise and WOT mixtures are good, generally the idle mix screw is more used to trim the cruise mixtures, so it can be a compromise.