AFR slowly richens at idle

I've looked into it... but I'm cheap :) Maybe I'll just build my own, I have a well-stocked junkbox.

Besides, the load will still be all there once it's fully on - so the idle rpm still has to be higher than I want it when the fan is off. Maybe not quite so high, since as you mention it won't be a sudden full-on (~500W electrical or about 1 hp at the crank, allowing for inefficiencies. The starting surge is probably twice that for a couple of seconds). On the other hand, since it won't always be running at max, it might be easier for the engine to deal with.

I have tried everything in carb tuning (and ignition timing) but this cam just has so little idle torque and vacuum signal to the carb that it has trouble handling an instant 2 hp load from the fan, let alone letting the clutch in below 13-1400. It wasn't designed for low-rpm street use, of course. Oh well, some compromises are necessary to run a BFC on the street!

Another possibility is to install an a/c idle solenoid and power it from the fan circuit :rolleyes: since it's old school anyway. :realcrazy: