Question for the experts.
Replaced stock fuel pump which had two lines from tank with a new Holley pump with a single line. I put a filter on the end of the small line to allow tank to breath. Everything seems to work very well except for one thing that might be a issue due to the unvented gas cap. I drove to the gas station, about 5 miles, and topped of the tank, drove about 80 miles and topped off again before heading back to garage. The tank burped out gas as I was filling it the second time.I had to fill very slow to keep it from burping. Do I need to change the gas cap to a vented type as it has never been an issue before the fuel pump change.

Thanks for any help, Ed S.

One more bit of interesting info.
My car is a 1970 LS-5,Van Nuys car, don't think it has had any engine upgrades, but during its life someone swapped the rear end with a 1971 rear which equals 2.73 gears. I changed to 3.55's, changed old holley to a new 770 street avenger and above fuel pump. Went from 10 mpg to 12 mpg and a clean pair of shorts.

Have a great day to all at TEAM CHEVELLE

Long story short, had the same problem after blocking off several hose connections on my tank ('70 El Camino). Maybe not the most sphisticated solution, but I drilled a small, maybe 1/8", hole in may gas cap.