What decides if you rebuild a carb?

[70DartMike]

I got a Holley 750 double pumper for free from a guy who was just trying to get out of wrenching. It's the newer style with plastic pieces on it. I opened the floats and both were clean, floats moved easily. My cousin has been on me to rebuild the carb, but an engine builder I know said to just run it.

What designates a rebuild? Is it in my best interest to just go ahead and rebuild this carb?

 

[crackedback]

If it's had fuel run through it and sat for any amount of time, you might want to pull the needle and seat assemblies and inspect the o-rings. They tend to shrink.

Accel pump diaphrams go bad too.

You could put it on and see if it's a leaker, if not it may run fine, leaker would need parts too fix it up.