My car with a Muncie and 3.36 gears and a ~26" tall tire runs down the highway at ~3100 rpm. I am right in that 15.2-15.5 AFR range. Crowding the throttle, it will swing to ~16.5:1 before power enrichment / secondary opening. WOT is ~12.5-13.0 range. Seems to get great MPG set-up this way, and there are no drivability issues. It is very responsive. At idle, the meter shows around 13.0, and light throttle in the < 15 to 40 mph range is 14.3-15.0.
That sounds like what mine is doing, except for the WOT AFR. My cruise AFR is almost identical to what you reported, so i think I've got the primary side set just about right. Going to the smaller rods and jets cut the WOT AFR with just the primary side to about 12.0 if I remember correctly. I might have to lock out the secondaries again and recheck it to be sure.
But do you think a good WOT AFR would be somewhere around 13.0, or is that too lean?
This ain't no hotrod, it's a 3/4 ton suburban with a 3.73 rear gear and a LT235/85R16 tire, gotta measure them again, but I think they're 28" tall.
My rpm at 75 is about 3200-3300 if memory serves. To verify that I have to either hope the local cops are having their morning coffee or drive 45 miles to get to the interstate, lol.
Maybe an AFR of 12.5 at WOT because of how heavy this thing is would be better, I honestly don't know.
I'd like to get it to where it gets decent mileage, I've got a LOT of scrap metal I need to haul to Tucson next summer, so it'd be nice if the scrap would cover the cost of the gas at least.
Thank you for replying.
Rick