Axle ratio with 521

[cwmcobra]

Hey guys,

I'm looking to tap your experience and recommendations for an ideal axle ratio for a West Coast Cobra with a 521 mated to a Richmond Gear Street 5-speed. I built the engine from a Ford Racing 514 short block with aluminum CJ heads, hydraulic roller cam with 0.600" valve lift, roller rocker arms, Edelbrock Torker II intake (hood height issue) and fuel with a Pro Systems custom carb. The car weighs about 2700-2900 lbs. and currently has a 9" solid axle with 2.75:1 gears and open differential. I've just acquired a Detroit True Trac differential and want to upgrade the ring & pinion when I do the install. This is strictly a road car! With the 1:1 ration in 5th gear, the engine currently turns 2200 RPM at 70 MPH. The engine is a torque monster, but I'm thinking of waking up the acceleration a bit with either a 3.10 or 3.25 gear ratio. With all the experience with this engine on the forum, what are your recommendations for ideal gear ratio?

I appreciate your comments.

Chuck