Join Date: Jan 2018
Location: Coopersville, MI
Need transmission and rear ratio. The new fuel does make a difference and a good tune up will also. Going from points to MSD ignition should also help fuel mileage. If your running a power glide it is probably one of the least fuel efficient transmissions in these cars and if it even has a minor slip it will affect fuel mileage. Granted I have yet to see a stock power glide that doesn't have a minor slip. If it is a stick shift it could be more about where you are shifting to get whatever giddy-up you can get out of it. 327 likes to produce power at higher RPM where your engine uses more go go juice.