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Discussion Starter #1
Hey everyone.

I have a 70 with a 350/th400. Currently my 8.5" diff has highway gears - 2.73s.

I'd like to get some more pep for running around town but don't want to murder my freeway drivability. I was considering 3.08s but wanted to see what you guys thought.
 

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3.23s are pretty good they have pretty good grunt and are still freeway friendly i wouldnt go above 3.55s though. the 3.08s you have suggested are the norm for a daily driver you cant go wrong there either im just giving you some options is all
 

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i was going to go with 3.55s or 3.73s on my car....and its my dd...
 

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so perhaps 3.23s?
Or you could install 3.42 gears which would be a compromise.

Have you determined how much bigger gear your carrier will handle?

My son is running 3.08 (which he hates) in his 68 Chevy II, and I have 3.36 in my 49 Chevy. We have identical engines and tire sizes, but I cannot tell the difference in performance.

Without an overdrive transmission, I think you must decide to cruise the freeways with ease or gear up for some tire burning.

IMO, minor changes are not worth the time and effort
 

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Both are gears that are normally used for the freeway. If you noticed any difference, it would be slight.
I believe my gears are 3.08...The same rear that was in the car when I bought it..1966 .230cui 6 cyl... now that I've put a 327 in it...It seem like the rpm's are kind of high...like I could use another gear...My tach shows about 5000 on the freeway....:confused:
 

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3.40's are an all around good gear, street strip. MAYBE 3.70's but now you're getting into that grey area where some will say it's fine on the street and others will say 4.56 gears aren't even too low.

3.40's should be about 2500 or so at 60 MPH with a 28" tall tire. Very livable and you can you can put on that smoke show when you want to.

There's many RPM gear tire dia. calculators out there. Do some playing with them and decide what your REAL intended purpose of the car is.

3.08's might be OK if you have the grunt to pull them, I agree you probably won't notice much difference from 2.70 to 3.08

Everyone has their own opinions on gears jst like anything else though. I like a higher gear and torque so that a low gear isn't needed.
 

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I believe my gears are 3.08...The same rear that was in the car when I bought it..1966 .230cui 6 cyl... now that I've put a 327 in it...It seem like the rpm's are kind of high...like I could use another gear...My tach shows about 5000 on the freeway....:confused:
WHAT??? 5K on the freeway? Is it REALLY, or are you exagerating? Did you not change/modify the tach when you changed from a six to a V8. Something doesn't make sense.
 

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I believe my gears are 3.08...The same rear that was in the car when I bought it..1966 .230cui 6 cyl... now that I've put a 327 in it...It seem like the rpm's are kind of high...like I could use another gear...My tach shows about 5000 on the freeway....:confused:
3.08 gears at 5000 rpm's would be like 120 mph!!!:eek: Either you got different gears, trans slipping, or your in 2nd gear! My sons car was 3.08 pegleg and mild 350. We changed to 3.73 and there was a huge difference in acceleration but 3500 rpms on the frwy. We had planned to go 700r4 but the gears happend first and he mostly drove city just to high school. Then with the 700r4 it became a new car! The engine pulls to about 5000-5200 bfore it starts to flatten out. With the new really low first gear it is now like a t-350 and 4.56 gears!!! Now when you nail it in 1st it revs quick and the motor lets out a scream it never made before :devil:(no exhaust changes). Frwy driving is at like 2200 rpms!!:eek: In my opinion other than a manual 5-6 speed this is the way to go!!:yes:
 

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I believe my gears are 3.08...The same rear that was in the car when I bought it..1966 .230cui 6 cyl... now that I've put a 327 in it...It seem like the rpm's are kind of high...like I could use another gear...My tach shows about 5000 on the freeway....:confused:
Yes, in 1966 the 3.08 was the gear for the 230 ci L6.

However, I think your tach is way off. I computed the MPH, using a 26" tire and 3.08 gears. With these imputs, you would be going 125 MPH.
 

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ya I have 4.10 with a 26" tall tire and spin at 3500 rpm at 60mph. I am looking to go overdrive (2004r) or possibly go to 3.42s :confused:
 

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Damng....What would be a good tach to use..I bought kind of a cheap one...Any Ideas.??...I'm running a 327 large journal out of a 68 camaro.. .30 over...4 speed Sag, performer intake, Eddy 600 and headers......Clue me please What would be a good tach..???:confused:
 

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Any decent tach should be fine. Stewart Warner, Auto-Meter, etc. Just make sure it's for a V8.
 

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Discussion Starter #19
Ok, back on track here. I just got my car back from the shop and have better details.

In my 70 with 350 / th400 I'm currently running 2.59s with 25 inch tires.

I'm thinking 3.23s but would love to hear any other ideas or insights before I take the plunge.

Does anyone have some experience to tell me if this switch would give me a very noticeable improvement in take-off power without killing my freeway speed?
 

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Ok, back on track here. I just got my car back from the shop and have better details.

In my 70 with 350 / th400 I'm currently running 2.59s with 25 inch tires.

I'm thinking 3.23s but would love to hear any other ideas or insights before I take the plunge.

Does anyone have some experience to tell me if this switch would give me a very noticeable improvement in take-off power without killing my freeway speed?
Decide what Rpm you want to cruise at, at 65 mph and that will tell you which gears to get...

With a 25 inch tire at 65:

Gear Ratio / RPM
2.73 / 2250
3.08 / 2760
3.23 / 2890
3.55 / 3180
3.73 / 3340


-Dan
 
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