I currently have a 79 F250 supercab, 4x4, with the 351M & 4 speed & 4.10 gears, & 33's. I am going to go to swap in a 460 & auto. Currently the motor is turning almost 3000rpms at 65 mph.

I want to carry an 11.5' camper and tow my early bronco at the same time.

Questions:

1. Would I have enough power with the 460 & auto to haul the camper and pull the bronco if I went with 3.54 gears to cut down on the rpms? How about 3.73's?

2. Would it help if I put in an low rpm cam to get more torque at the lower rpm if I did use the 3.54 gears?

3. What is a good rpm to be at when traveling 65-70 mph? Is 2500 rpm in the right range?

 

1. The 3:54's would be getting close to marginal. It would probably pull alright on flat land but mountains are going to kill it. The 3:73 will reduce your RPM by about 9% or 270rpm. It should be very drivable.
2 I'd skip the cam. The 460 is pretty well endowed with lowend torque already. I would invest in a good set of headers and dual exhausts.
3. 2500 rpm sounds good.
You may also want to invest in a five speed with overdrive when you are not pulling or loaded to save on gas.

Should be a good pulling truck when you are finished.

 

My truck is similiar to yours. When I built my engine I selected a cam that will have a torque curve compatiable with my cruising speed. The nice thing about the 460 is that it will make gobs of power even when you don't make a true torquer motor. I would go with a after market cam. Reason for this is you can build a much stronger motor than stock and not notice any difference in gas milage.

As far as gearing goes if you can afford to drop in 3.73 do it. Putting in anything lower would hurt your bottem end to much I think with 33's. Regardless of which gears you go with, after you have made a decision talk with your engine builder about what cam combination too run with.



Terry

771/2 F250 4x4 460
2001 Ranger Edge

 

Hey, thanks for the info. I think I will switch the 3.73 gears. I will be using it for daily driver more than towing & hauling.

 

You might investigate a "Gear Vendors" over drive and keep the 4:11's. It would kick you up to 3:25 in OD and has some other benefits. It's also bullet proof. It ain't cheap but my 4:11 traction lock center section cost around $1,100 complete. (new Ford motorsports). I kept the old 3:50 pumpkin for later use.

1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything