Jon, Feel free to take my comments and incorporate them into your original postiing. A list of diclaimers before your atricle would make good sense. I am sure you don't want folks doing these mods, just because they now know it is possible to do so....

Motorhead also made a few good points. Without an equal 4 corner Idle cicuit, sometimes it is best to have the rear transistion slots just barely covered by the rear throttle plates. But in some engines where Idle is too rich, then exposing the rear slots is a good way to lean it out a little, as long as the rears are not opened too much.

Also, I would like to add one more situation where this mod is the best fix for some users.

It is for part throttle driving, and low speed cruising. When driving at a constant RPM, and speed ( near 15 - 25 MPH), some folks will get a constant lean stumble, where mis-fires and bumbling along is always present.

This happens when your not quite at idle, and not quite usinig the main Booster Circuits. It is when your engine is running solely on the transistion slot circuits. The transition slot circuit also runs off of the IFR circuit. When this condition occurs, it is a great fix to increase the diameter of the IFR but 2 - 3 sizes (example .030 IFR to .033 IFR) to cure this part throttle lean.

But this does effect the idle circuit as well, and that means you need to re-turn your idling for less idle mixture.

______________________________________
[SIGPIC][/SIGPIC]
What is life worth, if everything comes easy...?
66 Stang 385+ HP 306 .494 /.520 225 durr @.05, 200cc Windsor Sr's, Edle RPM, C4, 3.00 posi, 575 Annular Mighty Demon, 22 MPG,