Hello Dave, I have a 72 corvette with a HOLLEY carburetor.  I noticed the carburetor is leaking a little gas on the back side.  I would like to change it out. Do you have any suggestions as to what I should get?  I have a 350 in the car.

  A Rochester Q-jet came on it.  The Correct number on the left side is #7042203. If you get it drilled and rebushed, from a quality rebuilder it will do you well.

Thank you for the reply.  I don't know what that means, but I will provide the information to the guy I'm taking it to. 

A kit is available that comes w/ the correct reamer and bushings.  Easy job to DIY.

The reamer kit is for the throttle plate on a q-jet. That makes it run bad but often does not leak fuel. It may have a replacement Holley carb. If that is the case you probably have a rear float bowl leaking. Find the number on the carb to identify it, and get a carb rebuild kit. There are only 4 screws that hold the bowl on. Remove them and take the bowl off. It may be stuck. Gentle persuasion may be necessary. Clean the gasket surfaces and just put the new gasket in place. While you are there you may want to replace the components, needle and seat, in the bowl for extra insurance. You will need to readjust the float if you replace these parts. The rebuild kit will tell you how. Here is an old racer trick. When you put it back together coat the gaskets and seals with cherry Chapstick. It must be cherry, not regular. This will prevent the gaskets from sticking, and they can be disassembled and reused.

The reamer kit I used on a friend's 427/425 '66 was for the Holley and worked perfect.

Unless one is going to drag or road race, the original Q-jet is the way to go.  Tuning Holleys for street use is a real PITA.

If you need to change Carb I would recommend edelbrock. Once it is installed and adjusted you shouldn't need to touch carb again for a long time. They can be purchased at your local automotive store. From your other reply it sounds like you are taking it to a mechanic. If you do get your Holley carb back from it. Holley is a great carb but constantly needs adjustments.

I always say that the good news about a Holley is that they have a lot of adjustments. The bad news is that they have a lot of adjustments. 

I had a Edelbrock 600CFM on a small block street motor and it was a bolt up, start adjust idle and go. They make good street carbs!!