1970442w30post

car is a 4 speed, rear tires are 275/60r15, Hole shot....YES! Drive across town....leaves a little to be desired. I was thinking of going down to 3.90's, not sure if I want to go all the way to the 3.42s. I want to enjoy the occassional 60 mile drive, but still FEEL the power. Anybody with experience?

InfoJunkie

4.66 gears 60MPH = 3355 RPM
3.90 gears 60MPH = 2808 RPM
3.42 gears 60MPH = 2462 RPM
What ever your comfortable with.

Run to Rund

I run 4.57 with a 27 or 30 inch tire. 4.66 with 26" tire is like 4.04 with 30".

InfoJunkie

Just to compare. 1974 Z28 factory 60MPH = 2881 so the 3.90's would make your car as driveable as it.

1970442w30post

Thanks for the quick response! Any idea how the 3.42s would feel taking off from a stop? I am used the the 4.66s so I dont want to lose the nostalgia of the launch, but am trying to detune this car just a bit from its strip heritage....

InfoJunkie

Putting in any of the gears you have named will feel less than you are now used to. It is something that you will get used to. I had some 5.13 for a couple of weeks,, went back to 3.08, but I got used to it.

stevengerard

I have 3.42s and love them but again its what you are used to, I think mine are a perfect compromise

Rickman48

It'd be kinda like starting in 2nd gear!
Here's the math:
2:54 X 4:66 = 11:83
2:54 X 3:42 = 8:68
1:88 X 4:66 = 8:76 - - pretty close!!

Think I'd consider the add-on overdrive and have the best of both worlds at my fingertips!! Also gives you 8 speeds to play with!
What could be more fun???

507OLDS

That's a lot of gear for that car.If you have lived with that,then 3:91's should be a picnic for you.
I have a set of one-off 5:38's for the 12-bolt O-axle,from GM,with a bunch of X's stamped on them.I can't imagine what those were like.Nice conversation piece though.

ziff396

I have 3.42's and they are great for both. I've had 4.11's and 3.73's before in my cheby's. 3.42 works really well for me on the street. It will still have plenty of GO!

compedgemarine

to me that much gear is a waste in an Olds for the street. Olds motors make lots of torque and low end power so for street driving you can run a 3:08 to 3:42 range and it will pull like a train if the tires hold. My SX has 3:23 and I like them so long as I dont hit the highway for to long at 75 mph.

Run to Rund

How much gear you should have depends on usage and camshaft, plus some other stuff of course. I went from 4.86 to 4.57 when trap speed got high enough (116 mph) that I was going up to about 6300-6400 rpm at the end of the quarter. If I succeed in improving trap speed some more, I may have to drop to 4.29 and go up to a 3.19 or 3.29 first gear to compensate. I don't feel that any of the power is wasted with those gears. I do drive on the street also, and just don't care if the engine revs a bit more. I will tire of the combination and build another engine well before I wear the current combination out.

1970442w30post

I am going with the 3.42s, plan on making this a driver....Thanks for the input!

Redog

I liked the 3.42's I had in my Delta, but if I had a overdrive tranny, I probably would have gone with 3.73, 3.90 or even 4.10's

gearheads78

Perfect choice for a Olds street car with no O/D

monzaz

You could buy a complete different rear and keep that one all set up with your high gears this way if you totally hate it you can just pop your original one back in again.

Got one if you need one ... just PM

It will be really weird for you, but as stated only time will erase the SUPER torque you get from those really steep gears. But the drivability to actually GET OUT OF TOWN will be a JOY. JIm

MN71W30

X2 Good choice, you won't regret it.

Rickman48

Don't know which trans you're using, but going from a close to a wide ratio will help compensate the change in 'stopight holeshots' you're used to!!!
Did a '67 Impala SS a couple years ago w/ a 3:08 that way - driveability and off the line power changed dramatically!

Run to Rund

66 W30s came with 4.11 gears. I once tried 3.42 and it was like the car was a 6 cylinder. It's all what you are used to, and what you want.

1970442w30post

The 3.42s are great!