Jeff,
If the car runs, you're already at the starting point. Do you have a copy of Wes Ingram's SPICA guide? (
highly recommended http://www.wesingram.com/). This outlines setting the fuel mixture both with and without an exhaust gas analyzer. For without; hold engine speed at 2500 RPM and turn richness in or out to obtain highest engine speed. Then lean the engine until it begins to slow down. Next, richen until it again slows down. If you marked the position of both extremes the correct micture is halfway between. BTW, for all pumps except 1969, the fuel cut off solenoid is turned
clockwise to lean. For 1969 pumps, turn the mixture screw
counterclockwise to lean mixture.
To repeat advice from Wes, Don't start messing with the mixture unless you have completed all previous steps in the tuning sequence. I can't emphasize how important this is; I had some tuning issues last year and Wes emphasized "Go back to the basics". I could not solve my problem until I went back and corrected a setting I was convinced was correct (it wasn't).
I've seen in a couple of places that to start tuning the mixture for a SPICA, you close the FCS ring screw all the way, then back off 6 turns, or something like that.
I have the '69 SPICA version with the small mixture screw on top (no FCS). Is there a similar rule of thumb of where to put this screw's travel for a starting point to set the mixture ?
Cheers,
Jeff