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Hey fellow Nova fans,

About to get my power plant installed and finally drive my 1972 Rally Nova!

this will strictly be a weekend cruiser, MAYBE 1 trip to the track per year.

Looking for help selecting gears.

350 sbc:
camel hump heads, minor porting, 2.02 valves
292 isky cam
11:1 forged pistons
670 Holly avenger carb
balanced
running av gas

Th350 trans:
rebuilt with common upgrades bands/clutches
3000 stall converter

8.5 rearend, currently has 2.73 gears.

275/50/15 rear tires

SO, what gears? I will cruise on the freeway occasionally, any one have a similar setup?

thanks!

Deven
 

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3.42 will be friendlier for the occasional freeway jaunt. I have 3.73's in my beast and a fairly loose converter so I'm hitting almost 4,000 RPM's at 60mph. If you had an overdrive trans, I would definitely recommend 3.73. They're a blast in streetlight to streetlight driving.
 

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Discussion Starter #3
3.42 will be friendlier for the occasional freeway jaunt. I have 3.73's in my beast and a fairly loose converter so I'm hitting almost 4,000 RPM's at 60mph. If you had an overdrive trans, I would definitely recommend 3.73. They're a blast in streetlight to streetlight driving.
What size tires? I definitely don't want to be at 4,000 RPM's at 60mph
 

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The 3.42 gears would be your best choice to wake it up without turning it into a pain to drive on the freeway. Unless you go to an overdrive transmission don't be tempted to use 3.73 or more. Mine has 3.73 gears with a Tremec 5 speed. Turns 2,000 rpm at 60 mph. Back when I had a 4 speed (1 to 1 ratio in high gear) I was turning 1,400 rpm higher.
 

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you'll like the 3:42 rear gears better with the lower rpm's. i couldn't find it in my book marks but someone put the link for a site you put your gears an tire size an i told you the rpm's a different speeds. maybe someone has that link.
 

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I have 27" rear tires and 3.42 rear gears and a Tremec 5 speed. In 4th gear which is 1.00 to 1 it turns about 3200 rpm at 65 mph. In 5th gear which is .62 to1 it turns about 1900 at 65 mph. I originally had a 4 speed and didn't like running 3200 on freeway so I went OD. Without OD 3.42's were good until you get to freeway speeds. But on the highway the rev's got old--for me anyway. Personally, without OD I would not consider 3.73's.

I like my setup a lot now with the 3.42's and OD but think 3.73's would also work pretty well now since I have OD.
.
 

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If you search around you can find online RPM calculators that take into account gearing and tire size. I suggest you play around with one of these and find your comfort zone.

Food for thought: I have 4.10 gears with a 4L65E overdrive tranny, and I turn 2000 RPM at 52 MPH in top gear. This is WAY too steep for the street. I'm facing the same dilemma as you in choosing the "correct" new gears. If I went with 3.73's, it would only lower my RPM's by 10 percent. So, you might find the 3.73's way too steep for your 3-speed. However, every situation is different, and it depends on what you're looking for. It's all a trade-off as the more kick you get in acceleration gives you more painful cruise RPM's.
 

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3:42s or 3:73s

Depends how deep your pockets are---you're already running av gas at $5.00 + a gallon---11:1 compression. I have 3:73s on a P265/60 15--350 Turbo--10:1 & can run any grade fuel. I used to have to mix av gas & 93 octane to avoid detonation when i had the wrong Cast iron heads---now aluminum heads & no detonation---no mixing for my 383. I hated the $$$ it cost to mix & go anywhere. I guess i'm saying 3:42s to help your wallet. My Nova turns 1900 rpm @55 mph with 3:73s---pick your poison. Dragstrip use---3:73s---Highway use---3:42s
 

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Without an OD trans those differential gears are not going to be too highway friendly in my opinion. I would want my highway cruising speed rpm's down around 2000 rpm range. Find a calculator and plug in your variables to see what your rpm's would look like. I would think that 3.08, 3.23, 3.31, 3:42 range would be a more desirable in a non OD comdination.
 

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I had 373 with a Muncie and it wasn't the best on the highway, but once I installed a built T-5 it was and I do much more highway driving now. I too would strongly recommend an OD transmission, but if it isn't in your budget, go with 342's unless the highway drives are short ones. With 373 at 55-60 mph isn't bad, but once I got over 60 mph it was more RPM then I cared for.:yes:
 

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Good combo

I feel if you could experience Both gear sets in your car,you would undoubtedly choose the 3.73's. With that C.R these would wake that 'sucker right up'.:yes:
Last three hot rods/ cars have had 3.73's. They suprise a lot of folks.
 

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Discussion Starter #13
Lots of responses - thanks guys!

Looks like I'm going with 3.42, thanks so much!

Deven
 

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What gears?

My 1970 was much like yours. 350 V8, turbo transmission and same gear set.

It didn't have much power on takeoff, but could cruise all day.

I swapped out the automatic for a Tremec TKO600 5-speed, but the original rear gears really didn't give me any improvements in performance, so I changed the gears to 3.73 posi.

I've got really nice acceleration and in fifth gear it turns about 2000 rpms at 60-65 mph on the interstate.
 
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