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Old 01-16-2013, 10:34 PM
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1961 Chevy truck, what rear end & gears for application?

I have a '61 chevy short wide that is my daily driver right now but fairly soon will be driven on the street mostly and will see a few runs down the strip several times a year during the summer months. I live in Oregon so that should give me about 4 months a year to play around, so I want it to be streetable and good fun down the strip too.

It has a 12 bolt truck open rear end with 3.08 gears, a TH350 with stage 2 shift kit and 2300 stall. I just bought my boss' old race motor and this is where it gets fun. It's a 350 bored .030 over, flat top 4 relief pistons, forged crank, h-beam rods, 2.02/1.60 valves, 1.6:1 high tensil stamped rockers, Weiand Team G single plane air gap manifold, hei dizzy with MSD module, high output coil, no vacuum advance and the lightest springs available on the centrifigul adv. so it gets full adv. right off idle, I think he said total timing was 30deg. at 3500rpm? 10.5:1 CR and the cam is a summit k1108 (specs below)

RPM Range3,400-7,000
Duration at 050 inch Lift: 244 int./254 exh
Valve Lift with Factory Rocker Arm Ratio: 0.508 int./0.533 exh.
Lobe Separation (degrees): 114
Camshaft Manufacturers Description: Rough idle, excellent high-end horsepower. Needs 10.5:1 and higher compression, 3,500+ stall, and gearing. 350+ c.i.d., bracket race cam.

He says this motor ran 450HP at 6200RPM on the Dyno with some kind of carb style fuel injection system which did not come with the motor so I'm going cabureted. I need to figure out what rear end will best for my application (described above), my low budget and the parts I already have.

I have a corporate 8.5" 10 bolt out of a 79 camaro with 2.41 posi that I was thinking of putting under the truck but I don't think it would hold up with that gear ratio and nobody makes a 3.08 or 3.73 gear set for the series 2 carrier. I know they make a spacer for putting higher (numericaly) gears on 2 series carriers but I've heard some horror storries that I don't want to live through. That being said, I don't know if I should get a series 3 carrier and gear set for the 10 bolt rear end or for the truck 12 bolt, and will the 3.08 12 bolt open rear get me by until I save up the money for the propper rear end solution?

Thanks in advance for all help. You guys are a great wealth of knowlege and I'm somewhat new to the technical aspects of hot rodding though I do have a basic grasp on what will generally make things go faster or slower.
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