an adjustable one will fix hesitation on take off
Not sure I agree with this. Hesitation on takeoff is often due to the accelerator pump washer being tired (can also be blocked pump circuit, timing etc). An adjustable main jet serves only the main metering circuit. There is no sudden increase in flow in this circuit when you moosh the accelerator (the opposite occurs - throttle opens, manifold vacuum drops, less suck on the main metering jet, less flow through the main metering circuit). The only way an adjustable main would cure that would be if the jet was open waaaaaaay too far (so that there is heaps of fuel to mask the vacuum drop). You would then have a very rich (and fuel hungry) car.
Not a big fan of adjustable jets (I think I own three or four). They were once described to me (perhaps by Ken or Doctor Terry?) as being really useful for taxis. Wind them in until you get awesome fuel economy, then drive until the valves are burnt and crispy
. Would not recommend them unless you are either VERY good at reading spark plugs with modern fuel, or have access to a wide-band O2 meter.
Cheers,
Harv
