4-11 gears vs 3-73

[tarussell]

Am running sbc 700r4 on 33 (advertised) with 4.88s, next tires will be as close 35 as I can get.
Can cruise 75 @3000 rpm 60-65 is 2k-2.5k. 60+ in 3rd is 3200+ finial ratio in od is 3.42.
If it was a dedicated crawler I would go 5.38 which is 3.76 in od
My cam and stall are smaller.
1600 rpm stall. Thinking of changing to 1800. Cam is summit grind 1102. 204°-214°@.050. .421 &.444 with 112° centerline.

Now that is a good example of well matched components in a given specific RPM range - everything is complimentary to each other.

The OP ‘s combo can work if it all works together in harmony and fuel economy is not a major factor - it needs to be in that power range to feel good.

 

[Fishinfool]

This one? https://www.compcams.com/mutha-thumpr-235-249-hydraulic-flat-cam-for-chevrolet-small-block.html

Yes

 

[Fishinfool]

Technically, you want enough gear to get you above the stall rating of the converter so it’s not slipping all the time (generating additional / unnecessary heat).

I just bought this a couple of weeks ago and I thought he said it was a 2800 stall but after looking at the paper work it’s a2100 stall

 

[Chickntrk]

3.73 to 4.10 is a ~200 rpm difference, I still maintain that if you're going to the trouble of changing gears you want to make it worth it. If this is truly a wheeler and not a highway cruiser 4.88

 

[Big Ray]

I can see where a 700r4 would benefit from the change.
Fwiw, most tire manufacturers websites have their actual tire sizes listed.
Here's a screen shot of my tires. The revolutions per mile are handy for reconfiguring your DRAC module to read properly.

General Grabbers X3, 33-10.5-15

 

[Fishinfool]

The only time

3.73 to 4.10 is a ~200 rpm difference, I still maintain that if you're going to the trouble of changing gears you want to make it worth it. If this is truly a wheeler and not a highway cruiser 4.88

it’s gonna be on the hiway is on the way to the mud maybe 50 miles max at a time on the hiway the rest it will be off road

 

[nvrenuf]

I agree, -for the return on investment- going from 3.73 to 4.10 the cost isn’t worth it (even if you can set up gears yourself).

I had 4.56’s w/ 35’s in my old crew cab and that combo was great. I tried 5.13’s for a while but they were a little much for a daily driver.

 

[Chickntrk]

The only time

it’s gonna be on the hiway is on the way to the mud maybe 50 miles max at a time on the hiway the rest it will be off road

This is why I say 4.88…if the only highway is to and from trails, you’ll appreciate the lower gearing more in the woods.

 

[Wes Harden]

I have 20k plus highway miles, towing, traveling, on my 4.88s with and od is like 3.42 at high speed

 

[Fishinfool]

Thanks for all the great info, I’ve decided to scratch the 4:10’s just not positive if I’m gonna go with 4:56 or 4:88, this is a great site for people like me that know enough about mechanics to get myself into trouble

 

[Big Ray]

Of gears and tire size...

Every inch of increase in tire size is equal to reducing the gear ratio by .1.
For example, say my truck came with 3.73 gears and 29 inch tires. Swapping to 33s will have the same effective gear ratio as 3.33 gears.
That's why we regear, to put the engine back in it's proper power band.
The taller the tire, the worse the effect is.

 

[Big Ray]

Good thing you brought it up.
When I saw 2800rpm stall, I don't think 4.88 would be good with this.
4.56 would probably be best.
But those who said 3.73 to 4.11 is not worth it, I did exactly that and couldn't be happier.
Stock TBI 350 with 700r4, and it was a dog with 33" tires and speedo was off.
Went with 4.10 axle and it was good acceleration and the speedo was spot on.

My tires were true 33"
Most 35" tires are 33-33.5"
But to the OP if you measure the tires we can give you better advice.
4.56 would be a safe bet regardless

What did it come with, 3.42s?
700r4 need all the rpms they can get.

 

[imiceman44]

What did it come with, 3.42s?
700r4 need all the rpms they can get.

It was 3.73

 

[4x4blaze]

I'm currently running 4.56's with a 3200 stall in my 700r4 75 K5 with 33's and HATE IT. Therefore I'm actually planning to do the opposite and switch to 3.73 from 4.56. With the 4.56s currently, it's shifting to 3rd by the time I cross an intersection. 1st & 2nd gear are relatively useless since it shifts out of them almost immediately.

That being said, my truck is built for an entirely different purpose than yours. It's a cruiser/all wheel drive gasser It's a 4x4 "hot rod" truck. So I'm shooting for street performance more so than off road performance. This truck won't ever see a gravel road lol. So for a wheeling type truck, they will probably suit you perfectly! Will definitely have some grunt.