I was adjusting the valves again today on the Tbird 312. I have a some clacking type racket coming from the area of the timing cover/fuel pump. I was thinking it may be a water pump so I removed the belts. Same noise. Seems to be getting worse. The fuel pump is sending fuel to the carb, no problem there. I put my stethoscope on it and can hear the noise where the pump goes into the timing cover and I can also hear air pumping out from the bottom of the vacuum pump part of it. I can't imagine what else it could be. I finished putting the engine together last week and it runs good. The fuel pump eccentric went on as per the manual. Any advice? Carter or Airtex pump best?

57 Black Tbird 312/auto