I was finally able to fire up my resto project yesterday after finishing the motor and had a weird problem occur. After starting the 318 it fired up and idled great until I pressed down on the brake pedal to see how the tranny was and the rpm's went up like 800 more than startup idle. When I released the pedal the rpm's came back down. I tried it again and same thing only when I released the pedal the rpm's just kept climbing! WTH?? 🤔

 

You have a leak in the booster.