What size is the inlet thread on my rochester 2GC carburetor. I purchased a new old stock carb and it doesn't have an inlet fitting. Thanks

 

If the carburetor has no inlet threads, I believe the correct size is 7/8-20 male (Thread length: .525") 5/8-18 female w/ inverted flare - same for both the 2G & 2GC (7/8" diameter inlet with 3/8" steel fuel line). You'll need to validate this, but I'm rather confident regarding the sizing at least up until 1972. I've read there was a change in sizing from 1973 forward, but I don't know.

Here is a self-tapping fuel inlet fitting: https://quadrajetparts.com/self-tapp...ing-p-130.html
More inlet sizes. Some you can go oversize or downsize based upon configuration parameters. Note some have extra length if required: https://quadrajetparts.com/inlet-fittings-c-72_87.html

 

my carb is a small bore 2GC that came on an F85 215. the threads are either a 1/8" npt or 3/8"-24 just not sure which one

 

The carb came off of a 61-63 F85 with the 215 engine

 

The threads are NOT NPT. They are straight threads. The seal is the inverted flare.

 

Thanks for that info. I didn't want to screw in the wrong thing and mess up the threads.