Jet Gas Mileage

JFromm
JFromm Senior Contributor
How many miles per gallon should I be getting with my Jet Twin H Stick shift with automatic rear end car?
I can't seem to get more than 10 miles per gallon and that doesn't seem right.  
The car has been timed, tuned and all the ignition parts have been replaced.  One Carb has been rebuilt and synched.  When I try to synch the second carburetor (that hasn't been rebuilt),  with the first carb, the idle goes so high I am afraid my engine will blow up.  
Any help would be greatly appreciated.  

Thanks