I just finished installing a new edelbrock high flow water pump, 180 degree thermostat (yes, I drilled a small hole at 12 o’clock position), sve 3 core radiator and sve dual electric fans. My issue is with bleeding the antifreeze. First, I filled the radiator until full, started car with cap off and let run. I kept adding antifreeze as needed, however, when the thermostat opened I had a water flow of antifreeze coming out of the radiator! So when this happened I let the car cool and then disassembled the thermostat housing and drilled the hole in the thermostat at 12 o’clock since it didn’t have one. I reassembled with high hopes and repeated process and same issues, car opened thermostat and another water spout of antifreeze out radiator cap. Yes, I was fairly passed as I spent 45 minutes cleaning up the prior antifreeze mess. So, Should I be keeping the radiator cap on? In the past I always left the radiator cap off to burp the system.