I have converted my later model B to HIF-4 carburetors and found that the standard ABD needles were too lean in the middle RPM range. I cannot use the standard Cooper Cans due to limited space in the engine compartment so I'm using the K&Ns with a stub stack. I switched to the ABY needles and the car runs great, but I'm not happy with the economy I'm getting. The engine runs "cold" at speed, barely getting half way to the "N" on
the temp gauge, which leads me to think that the car is running rich. Would going to an AAA needle improve my economy since it runs leaner in the middle range?
Obviously having an onboard A/F meter would tell me a little more about what is going on at cruising speed, but I could just get another set of needles for 1/4 of the price of an A/F meter.