Once the throttle body has been cleaned and re-surfaced, the throttle shaft bores are inspected for wear with a "go/no go" gauge. If they are found to be worn, the baseplate is bored out and oversize bronze bushings are driven in and reamed to size.

One step many rebuilders skip is removing the well plugs and/or emulsion tubes from the metering blocks before cleaning. I remove them on every Holley I build, whether it's a full restoration or just a basic rebuild. You simply can NOT get the metering block 100% clean without removing these components!

Some other common issues with Holley carbs are stripped needle & seat threads and stripped fuel inlet threads. In some instances these can be repaired with threaded inserts, but unless the parts are unique and proprietary to the unit in question, it's often quicker and less expensive to simply replace the stripped components.