hello, this is my first post to a new forum so excuse the cherry.....I have a 396 with 10.25 to one ratio and comp cam 268H along with MSD, headers, edlebrock performer alum. heads, rollers with 1.7 ratio air gap intake and a 750 street HP mech. secondary in a 67 camero with a 6 speed and a 4.10 final ratio. engine timing is 34 all up....

car runs strong but gas milage sucks. I have a split second AF meter installed and can see at cruise I am way rich. I have purchased a set of quick fuel tuneable metering blocks and am about to start dialing in my idle feed circut along with the idle air bleeds to lean out my cruise circut. Car has 10 11 inches vacuum at idle and about 9-10 inches at 1600 RPM (this is 65MPH in 6th gear)

I have read the article by Stan Curry in CHP where he explains this proscess in detail....does any one know how I might speak with stan and determine how much smaller to go on my IFR and my IAB as an intitial change for my carb......I am totally lost as far as how much change is a good starting point.

I am hesitant to start this project without some good advice....thanks  

I would probably start on the air side for sake of simplicity in adjustment. The air side of the idle circuit is more sensitive than the fuel side and you should only change by five or six steps max without looking elsewhere for the problem.

Just as with any jet size, many would recommend working in intervals of two jet 'numbers.'

"Elsewhere" will be the fuel side (IFR, as you mentioned) or the even the high-speed air bleed for the main circuit. This emulsion will affect the time at which the main circuit "activates." Maybe you're starting to pull a little fuel from the main jet at these speeds and that's why you're way rich, but it's hard for me to know exactly when the circuits are "in and or out" in terms of function when I can't see the vehicle.  

thank you for the advice....I am also showing a little rich on my main jets but have not gone down in size yet.....does the main jetting (primary side) have any effect on the idle feed circut? I was thinking  that the mains do not come into play at cruise (light throtle) untill 2000 rpm plus???? and that by opening or closing the high speed air bleed I can vary the rpm range in which the mains come into play......?  

In the article by stan curry they radically reduced the idle feed (fuel) from .036 to .020 and then dropped the idle air from .070 to .032....with the explination that after the reduction of idle fuel the car would barlely idle with screws 3 turns out so the idle airs had to be reduced to bring more fuel to idle circut.........I guess they mean more fuel sooner....to the idle circut.

It is easy for me to understand the A/F relationship of main jets and power vlaves and squirters and cams.....but I have no feeling for air bleeds or fuel restriction on the idle/progressive circut.....thanks again for the reply....John  

The main jet has an almost negligible affect to the idle circuit. The idle-feed restriction is the most significant change that can be made to the fuel side of the idle circuit...

I don't doubt that Mr. Curry made the proper change to the idle circuit in that carb but maybe he didn't explain it that clearly. Since he drastically reduced the amount of fuel available at idle by reducing the IFR size, it leaned the engine of course - then by reducing the size of the idle air-bleed he richened the mixture of the fuel available to the idle circuit. The point at which the idle circuit "activates" really isn't relevant because it's active all the time - or it at least when need be.