After rebuilding the Rochester 4GC on my newly aquired 62 Starfire, I still wasn't happy with it's performance. I swapped it out for the 4 barrel Rochester that ran flawlessly on my 70 Cutlas with a 350. I used a spreadbore to square bore adopter plate that I had lying around and all matched up fine. Redid the throttle and T.V. linkeage and refitted an extra air cleaner base I had so that all looks original. I know that the cfm for the 70 is 750, but can't find out what the original 4GC was rated at. Any one know? Although the car runs much better, I'm concerned that it might be overkill. I might consider trying an extra 500 cfm Edelbrock my son has on his shelf. Any thoughts?

 

Overkill, it's not - the Q-jets secondaries will only open as much as the motor is asking for, hence the 'vacuum secondary' designation!
These carbs were used on smaller motors than yours - 301, 305, 307's without incident - and work very well!!
Keep your GM car ALL GM!!!

 

If your Starfire has the original engine-a 394 c.i., a 750cfm quadrajet shouldn't be overkill.