I am working on my triple SU carburetor setup and have come upon an anomoly. I was able to obtain a replacement Suction Chamber and Piston Assembly which appears to be completely new and unused. The molded in numbers on the Suction Chamber (AUC1040) and the Piston (AUC2053) match the numbers on the old components. However, the drilling for the Jet Needle (UM) is about 0.124 inches in diameter on the old piston while the replacement piston is about 0.343 inches in diameter! What jet needle is the replacement piston intended to be used with, or is there a bushing available that would allow the replacement piston to be used with the UM Jet Needle?
Thanks, Bob
Submitted by rcmaury@bellso… on Sat, 05/18/2013 - 23:06
The triple carbs use the UM needle as stock with a .125 base. Some of the XJ sedans that used the 2" dual carb setup had smaller needles and will not work properly in the triple setup. Use the pistons that fit the UM needles