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What would be the best gear to run on the street with the occasional run down the track?
 

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Depends on your tire size, engine, and transmission. I run 3.73 rear gears in both of my cars, and it works pretty good all around. I'd love lower gears for the strip, but I'd love taller gears for the freeway. So for me a good compromise are the 3.73 gears.
On my Austin the rear tires are 28" tall, so on the freeway I'm usually cruising around 3,000 rpm. I'd like that to be more around 2500 rpm, but then I'd be too tall for the strip. My TH350 is 1:1 final drive, but the SBC engine handles the higher rpm OK.
On my Falcon the 3.73 means more like 2750 rpm on the freeway because of the taller 30" slicks, and that's better for the BBC, as higher rpm's on the freeway don't work as well with a BBC as they do with the SBC. But since it's got way more torque and HP, it works OK on the strip with the 3.73 and taller tires.
 

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Hi, 1946Austin has some great info. You are better off to make sure your engine, trans and gears are matched for what you are doing. There are lots of online dyno/programs that you can change inputs like gear ratios and see how it affects rpms et's etc. I have ran gears in street strip cars from 3:08 to 4:10, Small blocks tend to do better with more gear especially in a heavy car. If you are running a big block with lots of torque you can get away with less gear. Also if you are running an overdrive trans you can get away with more gear, a non overdrive I would probably stay 3:73 to 3:08. Also it depends on how much freeway driving you are planing on doing. I have seen some people put way to much gear in a street car and end up changing it due to poor fuel economy and it spinning the engine too high. I have ran low 12's to high 11's with 3:73 in a 3800 pound street car with a mild 454 28" tires. It was a bit much gear on the freeway for long hauls with the big block but had no problems in town.
 

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And for this reason the 700r4 was created. Very low first gear and an overdrive final drive with h a lockup converter to help get you both worlds. With the low first you can launch like a 410 and cruise home like a 308. I don't have one myself but I know guys who ran 10 seconds using one. Then you could use Valls suggestion for a 373 and have almost both worlds. I say almost because you never really have both on a normally aspirated and Carbuerated engine. If you use electronic fuel injection you may come closer to both worlds.
 

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My Henry J with a 700R4, 4.10 gears and 29" tires goes down the road at the same RPM as my '36 Ford pick up with a turbo 350, 3.00 gears and 27" tires. 1st gear with the 700R4 is kind of worthless on the street, though. It shifts to 2nd before you cross an intersection or turn all the way around a corner.
 
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