Just installed the four speed in my z28 a while back. Finally driving it around some. Its great mostly. Except on steep hills I can't shake the feeling I'm unintentionally hurting my motor. Feels lazy. I kinda expected that though. Hear close ratios like 4.11 gears and up. Bought it years ago. Wanted to try it. I like it but in the future 4.11s will happen. So in closing if your gonna install a close ratio 4 speed behind a 350. Gear up man.

 

I was sleepy out of my mind when I wrote that. Guess what I was trying to say. Is its awesome but there is a fine line between stalling out and burning out in my car now. Lol. 78 z28. Motor is I would guess real close to stock.

 

There's only .32 difference between 1st gear on a close ratio vs. a wide ratio Muncie. (2.20 vs. 2.52) I really doubt if one or the other would make a difference in hurting the engine, unless it's already tired. 4.11 gears would be a great launch, but since both trans have a 1:1 4th gear, it would sure hurt the highway driving, and most likely put even higher stress on an engine than the slight 1st gear difference. Probably be wound pretty tight at 55-60 mph with 4.11 gears in the back!

 

Whew I thought I was gonna get all kind of shouldn't have put it on with 3.73 gears kinda responses. Good to hear about what I did isn't too uncommon. Thanks man. Got a feeling I'm gonna go with 4.11 soon anyways thoughl . my cars a day off toy so long trips and mileage aren't too big of a deal for me. Drive my motorcycle all I can so I can afford to feed my z28.

 

FYI,close ratios are 2.20 first gear.With small engines they usually dont like gears taller than 3.90s.With big engines like 454s they act better.JMO,Tom

 

I've got a Super T10 in my OT gasser behind a 464 BBC, and a 3.73 rear axle. I'm also running pretty tall 30" slicks, so the lower 2.64 first gear I have still feels taller with those tires. I wouldn't want a lower rear axle ratio, as it's doing about 2700-2800 down the freeway now, and I don't like winding the engine tighter.
I'm running 3.73 behind the 327 in my Austin sedan and it runs 3,000 rpm at 65 mph with 27.75" tires, and I wish it was also lower rpm so I could cruise without being wound so tight.
I think you'll regret going to 4.11 gears pretty quickly. They're fun at first, but not for long, even just around town. You'll barely get through an intersection and be shifting to 2nd gear!

 

It depends on how the SBC is built. I've always liked 3.73 gears behind a SBC for the street, and preferred 3.42-3.55 gears behind a BBC. If the engines are built to wind higher rpm's, then a cam with a higher rpm range might require a lower ratio to get the engine up on the cam quicker.
Most street cars are using shorter tires today, and lower ratio rear axles compound the problem further. So a 3.90 with a 24"-25" rear tire is wound tighter than the same car with 28"-30" tire. Most strip cars use taller slicks, and want the engine wound out as they go through the traps, so a much lower rear ratio is used to maximize the engine's rpm range.

 

It all depends on what you want to use the car for. The close ratio box with 2.20 first and a 3.73 gears will result in total gear multiplication of 8.25, as compared to a gear box with a 2.64 first which with the same rear gears will produce a total multiplication of 9.54. This means that the torque at the rear wheels will be 1.1 or 10% greater with the wide ratio box. So for street use the wide ratio box is a better choice as it allows you to get away with higher rear gears. However, if just want maximum acceleration stay with the close ratio box and choose a rear end gear that will have the engine revved out to the red line as you cross the the finish line in third gear. The close ratios will keep the engine up in the power band as you shift through the gears. You want to limit the number of shifts, as each time you shift the car actually looses a bit of speed, that is why you want to avoid shifting into fourth. The higher in the rev range the power peak occurs, the lower the rear end gears you can get away with.

 

4:11 gears will be pretty useless on the highway. My 79 Z28 does 62mph at 3000rpm in 4th with the stock 3:73's. I've often wished it had an overdrive to allow a higher cruising speed. I figure 70mph is about tops for sustained cruising as the engine is racing away at 3500 there.

With 4:11's, you couldn't really run more than about 60 on the open road.

How often would you be racing other cars from a stop light anyway?