[rpmerf]

Yes, the air / fuel gauge takes the tuning to a whole new level. I installed a cheap narrow band system in my truck years ago. Air / fuel gauge from my turbo car, and a $20 1 wire O2. I'm working on harvesting a wide band I never got working from a non running project.

I've heard that A/F might is everything. With 10-15% ethanol gas, you might be better off around 14.1 instead of 14.7. You still have to go by feel a bit to figure out where it is happy. The A/F helps you understand what it likes and what it doesn't. Cruise, you still want to lean it out til it isn't happy, then richen it up a bit. I've heard between 16:1 and 17:1. WOT, you want to richen until it stops getting faster, usually between 12.0:1 and 13.0:1.

As you've seen, carburetors like when everything is consistent. Things like air temperature can really throw off a tune. If you are tuning at 95* with 60% humidity, it will be leaner at 50* and 30% humidity.

I'm going through a lot of this myself right now. I found out I've had a decent size vacuum leak since I got the truck 8 years ago. It's running super rich now, like pegs the narrowband once I give it gas. The jets and rods are unmarked, so I need to shoot in the dark a bit to estimate the jets and rods I need. It's been 90*+ during the days and the air feels like soup, so that really doesn't help. I need to get it out at like 6 AM when it is like 75-80*.