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Old 09-19-2013, 11:59 PM
Skips Blown 55
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Rear Gearing Recommendations

I know that you have been asked this question a thousand times, but this is 1001 !!! Best all around rear gearing...........street/highway

I have a Blown Big Block 55 Chevy with the following:
496 full roller motor
8:71 blower running heads up (1 to 1)
Dual 950 Holley carbs
Comp Cams Roller (a little better than BDS Stage 2 Race Cam)
Turbo-400 1/2 built

Full Chris Alston back half
31 X 21.50 X 15 tires
American Racing 15" DEEP rears
Alston/Ford housing (9")
35 spline axles with big bearings
Four-Link suspension

I can do the calculator formulas, but what is your personal recommendations for the final gearing for mostly street and some highway. I say that I'm not going to run it, but there are others that have said the same thing !!! This is mainly for two old people to get hamburgers in. I am looking for best all around by experience, not calculator.

Any and all recommendations are greatly appreciated.

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Old 09-20-2013, 05:06 AM
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3:50 to 3:70 would be my choice.

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Old 09-20-2013, 07:33 AM
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Look up your camshaft information. there should be a "cruising RPM" for it. I wouldnt go any lower than that (numerically). But my guess is the same as above; 3.55 - 3.70:1. Remember, if you have a tall rear tire, it makes the rear gear ratio seem lower (numerically). Use this calculator. RPM/MPH From Gear Ratio Calculator by Wallace Racing
Input the height of your rear tire
Your trans ratio is 1.00
then choose 3 rear axle ratios; say 3.42, 3.55, 3.70

Pick the highest ratio that meets your RPM needs on the highway. But with a roots blower and not looking to run an ET; Id probably pick the 3.55:1. Its still going to be a riot to drive

Last edited by AutoGear; 09-20-2013 at 07:42 AM.
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Old 09-21-2013, 09:25 PM
Skips Blown 55
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Final Rear Gearing

Thanks Guys..........
I was thinking in the 3;50 range also. Wanted to make sure that I wasn't going too high. Had thought about 3:70, but thought I would give up more on the freeways.

I forgot to mention the cnc'd Big Brodix heads. I don't think that I'm going to be on the EPA's "Happy Birthday List".

Thanks again,
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