Originally Posted By: Scott_Tucker
I'd love to see that program.
This thread really hits me where I used to live. Its only been in the last 5 years that I've started seriously (and not all that seriously...) tinkering with EFI. From ~74 to ~2007, I just played with carbs. Most of them Carters. I love Thermoquads... do you think I'm crazy yet?
As for tuning... when I was setting up my last couple of engine builds and tuning the carbs, I just made an Excel spreadsheet with the dimensions of all the jets in my strip-kit along one axis, rods (with an entry for each step on the rod) on the other. Each cell computes the area of the hole that remains with the rod (rich or lean step) poking through the corresponding jet. Print out the sheet, take it to the garage...
To make a change, you see what is in the carb, and if you need to (for example) go richer on the power step but stay the same on the cruise step, you can quickly find the new rod/jet pair that increases the "rich step" hole area while changing the "lean step" hole area as little as possible.
Armed with a tool like that, tuning Carter/Edelbrock carbs becomes as easy as tuning a Holley.
Oh, and the other tunable parameter in Carter carbs which everyone seems to forget is the SPRING under each metering rod piston. The stiffer the spring, the quicker the carb enriches when you step on the throttle. Weak springs tend to give you a nasty flat-spot coming off idle, or even demanding power suddenly when just loafing along. A good strip kit will have a spring selection, and the factory errs toward too weak on the springs (in my opinion). I've also seen some strange shade-tree kludges too. I once bought a used AVS (in SUPER condition) at a swap meet. When I took it apart, I figured out why it was available so cheap. Someone had tried to speed the transition to the power step not by changing springs, but by shimming the existing springs with spare jets.