Lean idle. Rich cruise.
12.3 cruise and 14.5 idle after opening the idle mixture screw about a 1/4 turn
Idle screws are at 7/8 out now. Turning them out makes cruise richen up.
Changing the idle mix screws changes the cruise AFR means the speed your are calling cruise is still mostly on the 'idle circuit'. It should really be called low speed or low throttle circuit, and in fact that's the term Chrysler often used.
91 pump gas. Pump says contains no ethanol. Thanks
Only reason to avoid the ethanol is if you're not using the car much. Even avoiding the E, using pump fuel you still are dealing with relatively poor lifespan and the seasonal changes. On the other hand, if your car can run WOT in top gear on 91, then that's working out with timing curve on the engine, fine.
There's a sequence to tuning the carb that is useful. It reduces the iterations and dead ends in chasing (changing) because its based on the circuits interact. For example, fuel level effects everything. Next, all fuel exits the bowl through the main jets until enrichment is needed (PV opening). However, the restriction of the main jets is very large (or should be) compared with the idle restriction. So when we work on the idle circuits we can ignore the main jet. Without going further I think you get the idea.
1. Focus on getting the idle to run strong. This is defined as lowest reasonable rpm it will go into gear with the minimal drop in vac and rpm. Easy to test with an automatic transmission. With a manual trans to some degree you'll have to trust the automotive engineers - idle should be relatively rich - especially compared to emmissions era stuff. I wouldn't trust the WBO2 AFR number too much at idle but anything from 12 to 13.5 is at least in the ballpark. As long its not soot up the spark plugs it can even be a little richer if that's what's needed. The reading will change when placed in gear because of the loss of manifold vacuum = less pressure difference on the idle circuit.
1a. I'd work on the primaries as much as possible. The secondary fuel mix is helpful with low manifold vac but don't be afraid to restrict those screws further in that the others, becuase fuel distribution on the idle circuit is more about vacuum than air velocity. On the other hand the primary side is critical in getting the off-idle correct.
1b. Off - idle and idle is going to be controlled by IFR, IAB and the transistion slot exposure. So measure the primary transition slot exposure and make some adjustments with that to see the effect on idle.
2. Check the impact of the idle tuning on off-idle. Should be able to slowly accelerate from closed throttle to 35-45 mpoh without hesitations or sluggishness.
3. Main circuit. Depending on the car and gear ratios, Cruising on the primaries will be interstate speeds. At least 55 mph in my experience, at 60 - 65 mph should be enough load and throttle that most of the fuel is coming through the boosters.
4. Enrichment is full load/max acceleration in at least 2nd gear, preferably 3rd. This is 1/4 mile time (mph) or chassis dyno time.
