Tom - first, happy you now have it running to your satisfaction.
Instead of posting the base numbers, look at the center sections of the carburetors for identification numbers. The identification numbers will be STAMPED, not raised, and may be in two different areas.
The older YF carburetors had the identification number stamped on the edge of the flange of the center casting (bowl) where the bowl meets the lower casting (throttle body).
After a couple of years, Carter changed the identification stamp location to a vertical flat section on the bowl on the end of the casting opposite the fuel tank.
Carter numbers on the YF units will be either 3 or 4 digits followed by the letter "S", POSSIBLY followed by a second letter.
Examples:
788s
788sa
966s
2100s
There were TWO different throttle bodies cast with the 788. The later one superseded the earlier (but Carter wasn't planning on multiple carbs using these). I probably have the drawings for each, but they are on microfilm, and no offense, I don't wish to spend the time looking. Microfilm is a great archive, but a lousy useable format!
Two questions that I would ask, the answers MAY (or may not) improve the current state of tune.
(1) Have you synchronized the two carburetors (absolutely required for best results)?
(2) When you rebuilt the two carbs, were the internal vacuum springs replaced (NEW) with identical springs?
One reason I preach W-1's in a multi-carb environment is the fact that the W-1 has a mechanical power system. The YF has a vacuum power system. Different springs, fatigued springs, or the lack of synchronization can cause the YF's to meter at different calibrations, even if all else is the same. Also true of the Rochester B's.
I understand your concern for reliability. Some company (and I don't remember which one) has the motto "do it once, do it right".
Get your carbs set up correctly, and then FORGET ABOUT THEM!
The Carters on my truck (a non-Chevy V-8) performed flawlessly and were not touched for 18 years! Only after the truck sat in a shop installing factory A/C and upholstery keeping the truck inoperative for 18 months did the carbs require attention.
Again, congratulations on getting the driveability to your satisfaction.
Jon
