No, as the ECM isn't controlling the solenoid the primary rods will be in rich position all the time. But maybe as there are springs below the primary rods I think the rods will also go down when there is a high vacuum (lean condition needed) and when the vacuum drops (more fuel needed) the rods will go up letting past more fuel. But I should need to test that first to see if that works.
As I have already installed my wideband air fuel ratio meter I think it's very interested to do so yes. I'll look if I have some time to test this tonight
Had some time today to do the test. First warmed up the engine, then a 10 minute "round" to test.
First for the wideband ratio meter. A 14.7 (air) to 1 (fuel) ratio is perfect (theoretical). But when cruising 16 to 17:1 is not a problem (leaner so to say) when on the choke or WOT between 11.5 to 12.5:1 is perfect.
With the ECM, cruising was between 15:1 and 16.5:1, WOT dropped to 12:1. The ECM tries to lean out the mixture to 16:1 is normal with a normal primary rods setup.
Without the ECM, idling between 11.5 and 12.5:1, WOT dropped to 10:1. The ratio never saw 13:1 but the engine was running fine just a little rich. (like when cold on the choke). So you can drive it without the ECM and I think if you turn down the rich mixture stop maybe you can drive it around 13 to 14:1 which isn't a problem