Any FLAPS Kragens, Napa, Auto Zone and not too expensive. Some people like my UNK only ever use a vacuum gauge to time their vehicles. I hope some guys that are really knowledgeable chime in with the proper sequence of things for your engine. On a 235/6 its just hook up to the manifold port( windshield wipers) adjust idle speed and turn the dizzy until you get the highest vacuum number then check idle again then check vacuum again for highest number continue until the highest number of vacuum at said idle speed. T/C Steve
