Update: I installed a rebuilt Bendix master cylinder, bled the system and still have problems. The problem is the brake pedal "catches" at about 1/2 travel as you depress the pedal with the engine off, and when the engine running the brake booster pulls the pedal down 1/2 down (to approx. the same location as the catch), which activates the brake lights. Once the engine if off for 10 seconds or so, the booster bleeds off vacuum and the pedla returns to the full "up" position. All of this happens with or without the master cylinder installed. I also believe the pushrod from the booster to the master cylinder is extended too far, as the master cylinder was VERY hard to install and did preload the piston on the master cylinder. The vacuum line to the booster is OK. I am inclined to believe my booster has an internal problem and needs rebuilt. Recommondations anyone?
Dragracer, please see my post
here about finding brake system parts for your 1964 Oldsmobile 98.