Jerry, I had the same problem when I installed my Offey intake and Fenton headers. The problem is the intake and the header do not fit together. The header holds the intake off the gasket at the bottom or underside of the head causing a vacuum leak. I found it nessary to grind on the underside of the intake to allow clearance for the header. It's a spookey deal but it worked. Just go slow on the grineing and you will be ok. If you pull your intake and header off you will see where they an hitting together. That is where the grinding is nessary. Then you will be able to adjust the carbs.
