Explain this to me .. ??
If I understand you correctly your saying that if you put in lower gears with taller tires you would end up with what you currently have at some point ??

 

I have a 74 F350 w/460, 4bbl.,C6, 4.10 all stock and dual exhaust and 43K original miles. It has a lot of power and torque but I think the reason you feel like you have to "push" it is because of the basic set up of the 3 speed auto and 4.10 axle. It also hauls, on occasion a 3K slide in camper. I won't go more than 60 tops on the highway, empty, since it feels like the RPM's are too high and you have to push it. I had a 72 F250 w/390, 2bbl, C6 and 3.73 axle and it could cruise a little better on the highway but it didn't have quite the brute power of the 460. You may also feel a little frustrated because you might be comparing it and expecting similar performance to a newer truck. We tow a 6K trailer with our GMC Denali XL w/6.0 L Vortex. If you are expecting similar performance at highway, towing as a newer truck, it just won't happen. Night and day difference and unless you make a ton of modifications to the engine and install a gear vendor overdrive unit, it wont compare. I like our Denali as a daily driver, but I LOVE my F350 for what it is and won't make any modifications to it. BTW, your truck looks awesome!

 

Correct with taller tires, you are changing the final drive ratio. A bigger tire equates to a larger diameter gear, It will allow you a higher top end speed with a sacrafice of low end grunt.

For instance, a 10-speed bicycle. You start with the small gear on the rear axle and as you increase your speed, you are able to switch to the larger gear. But, remember what it was like if you forgot to switch gears back and tried to start on the larger gear. It made it very hard to say the least.

Lower gears = (numarically higher)

 

Yes. Gearing down gives you more torque to the wheels, larger wheels reduce force output.



Example (ignore the math, if you choose, and go straight to the bolded text):

Say you have 100 ft/lbs of torque at the driveshaft and 4.10:1 gear ratio; you'd have 410 ft.lbs. of torque at the wheels. Say your tires are 28" now...

28/12/2= 1.16 foot wheel radius

410/1.16= 353 lbs of force applied to the ground

-------------------------------------------------------------

Now, pretend that you switch to 4.56:1's and 33" tires.

100x4.56= 456 ft.lbs.

33/12/2- 1.375 feet

456/1.375= 331 lbs of force



Hey, lookie there! You geared down and slapped some bigger wheels on your rig and now it's even more underpowered!

 

If you want to tow, get a diesel. If you want to tow heavy, get an inline diesel. The gas motor can't compete with an inline diesel for towing.

A good mid-range cam would help you a bit.

 

@devino246 and the motor is running at what RPM ?
"(ignore the math, if you choose, and go straight to the bolded text)" @65mph



<table bgcolor="#eaeaea" cellpadding="0" cellspacing="0" width="700"><tbody><tr><td bgcolor="#FFFFFF">3.31
</td> <td bgcolor="#FFFFFF">3.42
</td> <td bgcolor="#FFFFFF">3.55
</td> <td bgcolor="#FFFFFF">3.73
</td> <td bgcolor="#FFFFFF">3.91
</td> <td bgcolor="#FFFFFF">4.11
</td> <td bgcolor="#FFFFFF">4.27
</td> <td bgcolor="#FFFFFF">4.56
</td> <td bgcolor="#FFFFFF">4.88
</td> <td bgcolor="#FFFFFF">5.13
</td> <td bgcolor="#FFFFFF">5.29
</td> <td bgcolor="#FFFFFF">5.38
</td> <td bgcolor="#FFFFFF">5.71
</td> <td bgcolor="#FFFFFF">6.17
</td> <td bgcolor="#FFFFFF">7.17
</td><td valign="top">
</td><td valign="top">
</td><td valign="top">
</td></tr></tbody></table> <table bgcolor="#eaeaea" cellpadding="0" cellspacing="0" width="700"><tbody><tr><td bgcolor="#FFFFFF">28"
</td> <td>2582
</td> <td style="background-color:#990; color:#fff; font-weight:bold;">2668
</td> <td>2769
</td> <td style="background-color:#F90; color:#FFF; font-weight:bold;">2909
</td> <td>3050
</td> <td style="background-color:#F00; color:#FFF; font-weight:bold;">3206
</td> <td>3331
</td> <td>3557
</td> <td>3806
</td> <td>4001
</td> <td>4126
</td> <td>4196
</td> <td>4454
</td> <td>4813
</td> <td>5593
</td></tr></tbody></table>
<table bgcolor="#eaeaea" cellpadding="0" cellspacing="0" width="700"><tbody><tr><td bgcolor="#FFFFFF">33"
</td> <td>2191
</td> <td>2263
</td> <td>2349
</td> <td>2469
</td> <td style="background-color:#990; color:#fff; font-weight:bold;">2588
</td> <td>2720
</td> <td style="background-color:#F90; color:#FFF; font-weight:bold;">2826
</td> <td>3018
</td> <td style="background-color:#F00; color:#FFF; font-weight:bold;">3230
</td> <td>3395
</td> <td>3501
</td> <td>3561
</td> <td>3779
</td> <td>4093
</td> <td>4745
</td></tr></tbody></table>
Green = Best MPG, this is what you would want to get for the best fuel economy and highway cruising
Orange = Best Overall, this is good mix of power/MPG and considered best for daily driving.
Red = Best Power, this will give you the best performance for towing power, but at the expense of your MPG.

 

^^^agreed. You can change all the numbers but you have to figure in the now also changed engine performance. There are so many variables, why even discuss that?

Don't forget, when these came out the max speed limit was 55?? As has been mentioned, to get the higher speeds, lots of things have changed in trucks. Upgrades will get you there, but not very cheap or easy.

 

You just had to ask

At 55mph w/4.10's and 28's,

(1.16x2)3.1415 = 7.28828 foot wheel circumference

5280x55= 290,400 feet per hour

290,400/60= 4,840 feet per minute

4,840/7.28828= 664.07986 axle RPM

664.07986x4.10= 2,722.72744 RPM... just don't forget to factor in torque converter slip

-------------------------------------------

At 55mph w/4.56's and 33's,

(1.375x2)3.1415 = 8.639125 foot wheel circumference

5280x55= 290,400 feet per hour

290,400/60= 4,840 feet per minute

4,840/8.639125= 560.24192 axle RPM

560.24192x4.56= 2,554.70316 RPM

 

What MPH does that chart consider "highway cursing" I'm assuming 50mph? Meh, I'll punch the numbers tomorrow to figure out for myself; I'm all mathed out for the night.

 

This all with a gear ratio of 1:1 and no overdrive 65 mph on the chart

 

Overdrive would sure be nice, wouldn't it?

As yes, you're right. Comes out to 64.97696 mph.

 

Kust drop a 6.9 idi diesel in it and tow awAy at an affordable price even.

 

 

Actually had a 6.9 IDI without a turbo the 460 gaser does much better towing but I only get 9 mpg max towing ..

 

Well that's because ford still wanted the 460 to be their "big engine". If you look at the specs, the 6.9 only puts out 315 ft/lb torque. Granted it comes at lower rpms than the gasser.