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Old 09-20-2011, 06:58 AM
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What gears in 76 Nova

Mornin all

I finally have my vortec combo together, and it runs quite well I must say. 94 350 block with massaged vortec heads and a comp 282hr. 3k stall and stock rear end

Anyway, I'm wondering what kinda difference it would be if i stepped up to a 3.53 w/posi. Would it be worth it? I drive about 15 miles on the freeway everday for work. I'm at 2500 rpm @65mph. I run stock 14 inch wheels. Can someone give me some insight on what size gear that might be, and what kinda diff I would experience if I swap rears?? Right now, it's fairly decent until I get over 3000 R's, then it screams like a raped ape!

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Old 09-20-2011, 08:27 AM
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Assuming a 225/14/70 tire @26.5" tall, 3.08 gear, 2500rpm, 1 to 1 Trans ratio.
= about 64mph. Going to a 3.55 gear would be about 55mph @2500rpm.
Go to the 2nd Calc here, "A MPH Calculator from RPM and Gearing"> http://hotrodworks.net/hotrodmath/quarter.html
Or here > http://www.f-body.org/gears/

You'll need an O/D Trans if you want to enjoy cruising with numerically higher gear ratios.

Trans--------1st-----2nd----3rd------4th Gear
TH350-------2.52----1.52---1.00--------------
TH200-4R----2.74----1.57---1.00-----0.67
TH700-R4----3.06----1.62---1.00-----0.70

3.55 X .67 = 2.37 ---- @1960rpm = 65mph
3.73 X .67 = 2.50 ---- @2060rpm = 65mph
4.11 X .67 = 2.75 ---- @2275rpm = 65mph

3.55 X .70 = 2.48 ---- @2050rpm = 65mph
3.73 X .70 = 2.61 ---- @2150rpm = 65mph
4.11 X .70 = 2.87 ---- @2375rpm = 65mph
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Old 09-20-2011, 09:33 AM
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so no 2.73????

Thanks for the help Ssedan! I appreciate it. I was thinking I had 2.73's back there this whole time. But I am positive my tach read 2500 @65 mph. So, being that I have a 3000 B&M stall, and the original th350, does that mean my converter slips while cruising @65, 70? I do have an external tranny cooler.

If I really do have 3.08's, I may as well run with them and just try to find me a posi. light the tires up from a light, and they will spin until I back out the gas and let the R's drop.
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Old 09-20-2011, 11:01 AM
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It's still possible they're 2.73s. The TC may be slipping several hundred rpm + your tire size could be different from my guess above.

2.73 & 3.08 were the most common sizes, 2.56 & 3.42 were also optional.
http://www.novaresource.org/axle.htm#standard
http://www.novaresource.org/axle.htm#1976

For an Open Diff, jack up one wheel and spin it 2 full Revs, count the # of DS/Driveshaft Revs. 2-3/4 = 2.73, 3 -1/10 = 3.08.
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Old 09-22-2011, 07:24 AM
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picture of

the tach and the speedo... If u look closely, it says 65 mph and the tach reads 2500 rpms... I want to keep my engine in the powerband more, it doesn'[t really pull until after 3500 rpms. Really, I'm trying to convince myself to fork over the money for some new gears. Everyone always rags on me when I leave a loooooong smokey motorcycle stripe down their block
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Old 09-23-2011, 12:12 AM
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I had -77 Nova with original 2,73 gears and swapped to 3,70 gears,which were too much and then 3,42 and they were perfect for 350/350 combo.i had 255/60/15 tires.
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