Eddy 1407

To echo Johnny Dart, it's going to take a lot of reading to fully understand everything. If you've not tuned a carb in the past, I highly recommend a wideband oxygen sensor. They can really help you figure out which side of rich and lean you really are on, aren't too expensive, and are fairly easy to install.

The statement that rods and jets have zero effect at idle is bull. Where do you think the fuel comes from? It's only a minor effect, but when I dropped from .100 jets to .092 my idle AFR jumped to 16 from 13.5. Changing from .070 (cruise step)rods (in the .092 jets) to .065 dropped my idle AFR from 13.5 (after readjusting) to 11.5.

Also, you may want to check the total number of turns-in you have on your curb idle. If you need to crack it open very far to control the idle, the transition slot will be over exposed and you'll never get the low end of the carb to function well. Easy check is to tighten your mix screws all the way (lightly seated, don't crank down on them) and if the engine is still running, then your transition slot is overly exposed. More timing can help raise the idle (and if it does, the engine probably wants more) and help you close the butterflies a bit to get the transition slot to function as designed.

I got close to dialing in my whole setup, but it was still fighting me a bit, so I decided to try adding more timing and everything improved significantly! So as all the experienced folks say: TIMING FIRST, CARB SECOND.

Verify that TDC really points at zero and work from there. As others mention frequently, it's not uncommon for a balancer ring to shift on the outside diameter. Once you know where your true zero is, it will be much easier. Don't be afraid to experiment with the timing but do realize that you might have to limit your total timing if the initial is raised much. I'd work on your initial timing, raising and lower, until your in-gear drop comes closer to ~200 rpm, and not 500+. Keep your curb idle around 900~1000 until all is well, then you can work it lower if possible.

If you simply swap the carb, it will probably just mask the symptoms but the root cause will remain. Your engine won't perform to it's full potential and worst case would be on the rich side of things and cause cumulative damage as the cylinders are washed down or carbon fouls your rings and plugs and valves.