vizard video on emulsion tube tuning

[jhirasak]

Thanks for the tip on the Vizard discussion on Weber emulsion tubes. Anyone that has a wideband O2 sensor (LM-1 in my case) in their exhaust can use that information to dial in their emulsion tube to account for lean or rich spots during the RPM range instead of going to a dyno.

In my case, the 48 IDA Webers that I purchased came with F7 emulsion tubes. When I drove it during the first jetting test run, it showed that the carbs went pig rich between 2400 to 3400 in each gear during acceleration. Also, the car would not cruise without running rough during this range. To correct for this condition, I selected a set of F11 emulsion tubes, which has high holes at the C and D levels as well as having a diameter of 8mm instead of 7.5mm. This cleared up most of the midrange richness but I am now a bit lean at WOT (approx 13 to 1, would prefer to be closer to 12 to 1). If I had selected the F3 emulsion tube instead of the F11, perhaps I would not have the WOT lean problem. Now, I am trying to decide if I should fatten up the top end with a main jet and air correction jet change or leave well enough alone for street use.

In any case, the Vizard audio on YouTube is worth your time if any of you are trying to correct for midrange fuel ratio or driveability problems and are confused about how to select another emulsion tube.

Comments?

John