<<<is a picture of the back-side of my "Previous" factory GM Throttle Body, (which I had CNC bored out to 52mm /Stock is 48mm) , Just to show what the "sealed off" IAC Circuit looks like on the factory units..... This is the way the IAC system was designed to work it's best with the accompanyning LT1/LT4 Intake manifolds and they're internal IAC port system, which distributes additional air-flow out to "each" intake runner as equally as possible ... and guess what?... it does work best this way, LOL......This all becomes VERY VERY apparent when your trying to attain the best possible Idle, and driveability charateristics out of a car with a pretty Large cam on a Narrow LSA, (and an Automatic transmission equiped car to boot)...... THE PROBLEM: Basicaly the aftermarket companies, for no intelligent reason at all (Yes I've asked several of them about it,lol) went ahead and Connected the two large throttle bores in this area and Eliminated the IAC By-Pass hole altogether, thus leaving the IAC valve with 100% of the responsibility for controlling ALL of the Idle, and Off-Idle charateristics (which it commonly fails miserably at, "on it's own"). PS: Here is another web-link with some good info, and pictures on the subject http://members.cox.net/chipsbyal/page/idle/index.html (Throttle Body Continued on next page)
