Trying to get 65 Mali finished up (for street). Engine is low comp/high reving buildup with about 400 est. hp and I intend a 100 shot of spray after tweeking and break in. Have 700r4 w/about 2200 stall. Local fellow with lots of racing experience is replacing the 12 blt. 3:36 peg leg with a Eaton unit. He's advocating a 3:90 ratio (say's if I really want to love it) above my initial interest in a 3:55 or 3:73 ring.

I know the 1st gear is alot lower in the 700r and can overcome somewhat of a higher ratio for launch at redlight (ha) but I really want the car to dig thru second and third and good cruise rpm at 60 for the car show / swap meet trips.

Any comments welcomed.
Thanks, Steve

I feel a 3:90 is just a little too low, you'll be in 2nd gear before you get moving good. I've driven them with 3:73's and feel pretty good. I'm running 3:31's behind my 700, and I love the combo, I turn less then 2000 rpm's at 70 mph with convertor locked in. It's also a tire fryer in 1st-2nd, and gets rubber in 3rd, mine is a factory posi unit, and I'm running a 425 hp 454HO GM crate engine, with a Holley 770 Street Avenger carb, and a 2500 stall convertor. I'm also running A/C, and powersteering. If I put in O/D and let it shift on it's own, it shifts consistent at 6000 rpm's.

depends on a lot of things; how much overlap, whats the compression, tire size, do you drive on the highway much,etc. ill say 373 to 410

Thanks for the replies gents. 8.7 comp for pump reg 245/55 R17's with GMPP HOT CAM. Most driving intended for cruises with some distance travels.

i think a 373 would be about perfect for your small block

I vote for 3:73's. I got it on my 700r4 and its nice.

More street then strip 3.55's max!!!!!!!! with often cruising on the open road.

Maybe 3.73 ONLY if your really going to be doing a lot of competitive racing at the strip on wk ends and you want to get more out of the setup on the strip.

But if not a lot of serious strip use 3.55 MAX!!!

Scott

With a 454 in my 70 Wagon, I used what Chevrolet used. If you go lower than a 3:55 buy two rear cover gaskets you will need them. A 700R4 has a 3:06 first gear. Shift points a 13-36-55. You car will move about 6-8 Feet the shift to 2nd.
My wagon comes out of the hole like a rocket (3:07 12 bolt), and at 75 MPH the 468 is turning 1950 RPMs. Chevy used 3:08s and 3:42 -- I believe my 03 Silverado with a 327 engine has a 3:42. It weights around 5700 lbs. and will burn tire all-day.
I agree with the guy that said a 3:55 rear.........
Your call ?????
Bob

3.73 is what I put in my truck with the 700, I was debating on the 4.11 or not. Now I kind of wish I went with more gear.It's a ton better with the 3.73 than the 3.08 though. Depends on the engine set up I guess,tire sizes also.

Trying to get 65 Mali finished up (for street). Engine is low comp/high reving buildup with about 400 est. hp and I intend a 100 shot of spray after tweeking and break in. Have 700r4 w/about 2200 stall. Local fellow with lots of racing experience is replacing the 12 blt. 3:36 peg leg with a Eaton unit. He's advocating a 3:90 ratio (say's if I really want to love it) above my initial interest in a 3:55 or 3:73 ring.

I know the 1st gear is alot lower in the 700r and can overcome somewhat of a higher ratio for launch at redlight (ha) but I really want the car to dig thru second and third and good cruise rpm at 60 for the car show / swap meet trips.

Any comments welcomed.
Thanks, Steve

A 'high revvin' motor and a 2200 rpm stall speed?

I used 4.10's at the strip and 3.50's on the road with my low revvin' 3500 stall SBC setup. I think guys worry way too much about the low first gear ratio, I never spent much time there. I kinda considered the 700R4 to be a 'Glide with a jumpstart and a nice lockup OD.

You need to figure out what's the lowest rpm at which your engine will run efficiently and factor that into your decision. Let's say you want to keep the rpm above 2400 (because it bucks and is inefficient at points lower than that) and you have 26" tall rear tires. The minimum speed you can reliably operate at with 3.55 gears, in OD and locked is about 75 mph. Here's a calculator that will show you equivalent mph for different gearsets and and tire sizes.
http://www.angelfire.com/fl/procrastination/rear.html

Very good point as I really want good back in the seat acceleration in 2nd and 3rd. Not drag racing as chassis is set up for the curves. Presently I am leaning to the 3.73. Any one with more personal experince with the "lower" gears that are Dissatisfied?

with a mild 402 w/Qjet, 700R4 and a open 3.55 our 71 is just about right... before we switched rears we had a 2.73 in there and lets just say anything over 2800 in OD was interesting

I had a 350 SBC in my 56 Studebaker 2 door wagon. I ran a 255 70 15 tire. I had a 355 8 inch rear end in it. With the TH 350, I ran 3400 rpm at 75/80MPH. Put in a 700R4 and ran all day long at about 2500, ran cooler, quieter and cheaper. It was great. My 86 Monte Carlo has a 305, with a 200 4R and 3:73's and it's fine too. My 71 1 ton pickup has a 402, with a 700R4 and 4:10's.........I'm searching now for a 3:54 rear end for it. Even with a 29 inch tire, that's still too much for me.

OK Guys ... Thanks a bunch for your comments. Settled on 3:73s. Did go down the road a bit with Richmond 3:90 and was awsome thru 3rd but had a "whine". After breaking back down found gears not lapped and returned for 3:73 Motives. Buddy say's I won't notice alot of difference (though he was the 3:90 fan but a racer too.) I appreciate all you comments and insights.

Another vote for 3:73s, that's what's in my 67. Richmond's, BTW.