So I finally had the cpp brake kit (drum to disc up front)put on even bought all new hard lines from front to rear.While the the car is up on stands the wheel spins freelly no bindind or uneven caliper install.71 chevelle drives fine but there's time when ill either take it for a 30 minute drive with no issues Or just to the store 5 minute drive and I can feel the pedal is hard and brakes are engaged.
After I park the car for awhile its normal again.

I thought maybe the lines being close to headers it heats up and causes the brake fluid to expand but
Like I said sometimes a quick 5 min drive would cost this also(brake line up against firewall like stock).

I hope somebody helps me asap we been having a 70 degree weather in sf cali on winter and would love to cruise thanks again in advance.