I have 411 gears in my 58 Vette with wide ratio 4 speed. I would like to take it on the power tour. I have been thinking I should change the gears to a better highway ratio thinking of 355's. How much would that improve gas mileage and drop the rpm's or does anyone have a suggestion as to what ratio I should be using. Thanks forum members for any info you can suggest. Bill58...

 

Buy a extra punkin that is in the threes anything from 55 thru 64
Pass car will work and set the 4.11 to the side for the trip
Then when it comes up again?
You will have a choice it doesnt take long to change
You wil get tired of the 4.11 pretty quick and it wont work the motor as hard or your nerves

 

If memory serves, four bolts on the housing flange and out pops the axles. The diff is as quick as 1-2-3. Be glad you are doing this on a C1 and not a C2; otherwise, you would be living with the 4:11.

My personal swap would be the 3:36 with a wide ratio. If you are looking for a diff, I may have a source for you.

 

If you just plan to use it for the PT, try REAL HARD to locate a 3.08 rear center section from a 59-64 pass car (the 62-64 will be more common). For driving the PT, there will NOT be a need for a posi rear. Changing the rear end center section is tooooooooooooooooo easy!!!!!!!!!!!!!.
If you can't find a 3.08 (and you should be able to), at the very least get a 3.36. A 4.11 on the PT is going to eat you alive in gas.
If you car only has the base, stock 283 that's very tired, it will still be able to pull a 3.08!

By the way, I mentioned locating a rear from a pass car, because if you tell anyone that it's for a Corvette, they will quadruple the price!!!
ANYTHING that is common between Corvettes, and pass cars, NEVER, NEVER, NEVER tell them you need it for a Corvette.

 

I went from 4.11 to 3.55, and then to an overdrive trans (.73 OD), which is now effectively a 2.59. Do about 2000 rpm @ 60 mph with 26.1" rear tire diameter. A 3.55 is a nice all around gear, but agree that a 3.36 is better on the highway. And with a wide ratio trans, even a 3.08 would work fine.

What engine?

Plasticman

 

i would use the 336 with a wide box and it would knock off approx. 700 rpm in 4th gear!!

 

IF I remember my high school math, 355/411 = roughly .78.

The reciprocal/inverse/obverse, whatever it's called would be .22 or 22%.

So assuming you're turning 3000 RPM at 60 MPH with 4.11's, a 22% reduction of the RPM would be roughly 2340 RPM with the 3.55's, a reduction of 660 RPM's.

That being said, I wouldn't buy a new ring and pinion. If you go that route, you'd need to buy a 3 series carrier, assuming you have an original 4 series carrier in the car. Then, you're ending up rebuilding the entire thing.

I'd buy a complete pumpkin. ANY rear, posi or not from a 55 to 64 Chevy should fit.

Tom Parsons has forgotten more than I ever knew, and he says 59 to 64. I always thought 55 to 64 would fit.

Chuck

 

engine in the 58 is a 283 with 327- 350 horse cam 10.5 compression ,high dome pistons with fulie heads about 7,000 miles on rebuild. Bill 58

 

I believe that '55-'64 will work. Tom's reference might have been to your locating a 3.08.

 

Bill,

350 cam is a higher HP cam, but gives up some low end torque. Being in a 283, that torque band shifts upward further (smaller cubes). What valves? I am assuming 2.02 with being "Fuelie"? If 2.02 intakes, torque rpm goes further. What intake and carbs? Stock exhaust?

Think you be best to keep the rpm up higher than a 3.08 would run. 3.36 is as far down as I would go, and you might be better off with the 3.55.

Would need a lot more info to make a full evaluation, but a 3.55 sounds like the best combo or even a 3.70. I think a 3.70 was "standard" for the C2 Vettes with the 327/350 engine (that is what I had in my 66 and it was a nice combo).

Plasticman

 

The valves are 194's manafold is eadlebrack ? carb is 600 holly. Bill58

 

Smarter choice with the 1.94's on a street 283. But still think better with 3.55s as the lowest you should go.

3.70 would work as well. Depends on what you find available.

Which Edelbrock (they make / sell many different styles, but most popular for Vettes is a Performer or a Torker)? Both are "big" manifolds for a 283, with the Torker being higher RPM oriented with a definite soggy bottom end.

Plasticman

 

I ditched the 4.11's in my 63 FI car several years ago and replaced them with 3.55's. I like the combo. I replaced the entire rear end assy, and kept the 4.11's on the shelf.

I finally got tired of howling down the Interstate at 3500 to 4000 RPM just keeping up with traffic. The 3.55's make the car much more "long trip friendly".

Replacing the rear on a C2 is much different than just replacing the "center section" or "pumpkin" on a C1. On a C2, you have to tear out the entire rear end, case and all. It's a big job.

You can change the pumpkin in an hour or two with simple hand tools on a C1 or old Chevy.

Jack up the car, take off the rear wheels and drums. Unbolt the 4 bolts on each axle retainer. Pull the axles back. Unbolt the driveshaft and the bolts that hold the pumpkin. Drop it out. Pop the new one in. Reconnect, add oil, and go down the road.

A number of years ago, I helped a friend pull the 4.11 posi out of his 62 Corvette. We replaced them with 3.08's as he was driving to California on an NCRS Road Tour. Well, he never got around to putting the 4.11's back in the car, so I bought the entire pumpkin from him last year.

It's gonna go into my 56 Chevy when I switch it over to a 700R4 automatic OD trans.

Chuck

 

What is current MPG and what are you looking for?

 

On the highway I have gotten over 16 mpg. What I'm really looking for is less rpm's .In answer to Plasticman about the manafold its an old one from the 60's. Bill 58

 

Any center section from '55-'64 will interchange. He may have been referring to when the 3.08 became available. I thought 3.08 was available in '57 or '58. I think '59-'64 pass car axles may be the same.

Considering the engine, the transmission, the car and the limited use for that gear, I'd go with the 3.36 ratio.

How fast do those guys drive on the Power Tour anyway? Maybe just leave the 4.11 in it. If the OP is just using it for the PT, it doesn't make much sense to change the gear just for that.

 

Was also in your shoes in 92. The LS6 in the 65 was screaming and thirsty on the NCRS road tours. Traded the 4:11 for 3:55. Traded Muncie for T56 6 speed ( 4th= 1:1 5th= .75 6th= .50 ) 850 Holley for the QJet, 292 Comp Cam for the Chet Herbert B6P roller ( Incredible low end torque, a must for MPG ) Went from gallons per mile to 22-24 MPG. I drive through town 30 MPH in 6th. 80MPH = 1800 RPM. No, it won't turn 11.95 in the 1/4 anymore but still has enough power to run with the big dogs.

 

I'm driving a 283 with 461 heads ,327/350hp cam and a 3.08 rear gear. It works great on the highway.

Bob

 

Do you know if it is a dual plane or single plane type manifold?
What rpm does the torque band pick up at?

Plasticman

 

One important question that has not been answered is "how fast are you planning on driving in the PT"?

I have owned my 61 FI for over 40 years and have driven it across the country, so I'll throw in my 2 cents. I used to regularly change pumpkins on Fri night to go cruising, then change back to the 3.55 to go to work on Sunday evening. With my buddy, it took a half hour.

I kind of use 3000 rpm as kind of a maximum rpm on the highway for my "comfort zone". Your comfort zone may be different. However, after many years with this car, that's where I have settled.

So match your anticipated cruising speed with your comfort zone. Anything suggested here will be better than your 4.11. I used to run 3.08, 3.36, 3.55 for highway gears. I didn't like the 3.08 gears around town for obvious reasons. But I sure did love them out in the desert when you could bury the throttle. For your purposes, they may be great. Remember you will spend most of your time at speed on the highway, so my suggestion is to gear for that rpm.

Have a good time on the tour!