70 chevy fuse problem

[70CHEVYBB]

I keep blowing the 30 amp fuse that comes off the positive terminal on the battery. I can drive a day with no problems then pull the head lights it will blow. I put a new one in and pull the head lights on and all is fine. I pulled in my garage and it blew with out lights on. All lights works fine all grounds ae in place and clean. I did remove the voltage regulator and wire in a 88 to 95 alternator. I soldered in a 5w 47 ohm resistor to make the internal regulator function. It works fine. Any ideas?????? I keep fuses in the ash tray. one more thing I have never had it blow a fuse while driving its always been in my garage or the one time I started it to pull it in the garage. just thought i's throw in another pic.