My car originally came with a 3.08 open rear end and 14" rally rims. Now I have a 3.27 posi rear with 16" IROC rims (not stock tire size, they are actually taller). When I am rolling at about 25 MPH, the speedometer says I am doing 50. Will putting in a speedometer gear that I have from an 85 IROC that is setup for a 3.23 rear and 16" stock rims be better, even though I h ave a 3.27 and bigger tires? What should I do? Thanks.

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1984 Camaro Sport Coupe - 73K Miles, Rebuilt 355 TPI L98, Crane 2032 CompuCam, Crane adjustible fuel pressure regulator, stock TPI intake, gutted air box with K&N filters
F41 Suspension Package, 700R4 Tranny, 3.27 Disc Brake Posi Rear
Hooker Shorty Headers, Catco High-Flow 3" Cat, Flowmaster 3" American Thunder Cat-Back
New Paint
Best 1/4 Mile Run (with old LG4 motor):
16.760 @ 80.74 MPH

Coming Soon:
Aluminum Drive Shaft

 

If you can tell us your tire size we can tell you exactly what gears you need.