Differential Gearing Question
I am upgrading from 28 spline to 31 spline axles and so am considering a gear change since I am changing the pumpkin (9 inch) to a 31 spline.
I currently run 3.70 gears with 26.5" diameter M/T Streets. Since I drive it on the street a lot, I am considering changing to 3.25 gears which would lower my cruise rpm and possible improve gas milage. However, I am not sure how much it would impact 1/4 mile times. The car is about 3550 lbs. horsepower peak is 6200 rpm. If it amount to a couple of tenths its ok, but if more I will probably stay with the 3.70 gears. Please advise your thoughts.
Rest of combo is:
466 with ported DOVE's, exhausts opened to CJ, and 2.19" and 1.76" Manley valves.
Cometic .040" head gaskets
Probe forged pistons with 11cc dish, heads slightly relieved and polished to give about 10.3 compression ratio
Scat H-Beam Rods
Torquer II Intake
950 CFM Proform/Holly
Lunati Solid Lift Cam 559/572 Lift, 237/247 Duration (at .050"), Intake C.L. 106/110 installed 4 deg. retarded.
Matching valve springs with titanium retainers
Howards roller rockers
Direct lube lifters
Ford Distributor recurved by Scott
2 " Primary Crites headers
1962 Fairlane estimated 3550 lbs.
C6 with 2800 stall converter