Just installed a Holley 750 on my sbc 400. The rear bowl tube is shooting gas out of it when I crank the motor. I have checked the needle , I have changed the front needle to the back, and I have adjusted the float down as low as I can get it. Do I need a feul Pressure regulator ( I am running a mechanical fuel pump)? Gonna try it tommorrow anyway. Just thought I'd run it past you guys.