3/8 vs 5/16 fuel lines

mbaird said
In my 69 Swinger 340 with a 408 w2 I chose to run both electric and mechanical . The electric only gets used for racing or to fill the lines after a long rest . And I used a 1/2" pickup in the tank and feeding into the Holley pump just outside it. My thinking is the pumps will have an easier time sucking up the fuel out of the tank .

I'm thinking if the throttle and secondaries are all working I'll start replacing the smaller fuel lines one section at a time till I get back to the gas tank. Maybe I'll see something else while I'm down there. I just don't understand why it's not popping like it's lean. Thanks all and Merry Christmas. Jim