JET
A small precision-made hole. Often a brass fitting placed inside one of the passages of a carburetor to control the flow of gasoline, air, or air/fuel mixture.

JETRONIC SET
The fuel pressure at idle and with the manifold-pressure hose disconnected can be measured using the pressure measuring device from the Jetronic set.

JOULE
The Joule (J) is the unit of measure of energy according to the International System (I.S.). It corresponds to the work applied by the force of one Newton (N) to produce a one metre (m) displacement.