Just got a customers car running and he gave us a new Edelbrock carb to put on it. This is a rebuilt 289 with Edelbrock RPM heads, Edelbrock 600 carb, Edelbrock Performer manifold, headers, mild unknown cam. The engine sounds great when it was fired up for the first time. We broke the cam in properly and made timing and idle adjustments with it. I took it out in the parking lot to see how it would run and it has a big hesitation to it. I thought the accelerator pump did not work by the wat the car falls on its face. I pulled it back in and looked at the accelerator pump and it squirts a good amount of fuel. I have never messed with an Edelbrock carb, I am a holley guy. One thing I failed to mention is right now this car has no exhaust. It is open headers. Should I wait until the exhaust is put on til I try to get this hesitation worked out? Should I try the next size metering rod? Is the Edelbrock just a piece of $hit? The timing is properly set and the car pulls 15" of vacuum at idle. Any tips?