I recently bought an 86 F-150 2wd with a 302. It has a 4spd. (3spd with overdrive) manual and I cannot get anything better than 13 MPG!! Which would be OK if I had any power but I don't. My rear end is geared with 3.00 pinion (according to ford customer service) which I know is a very "high" gear. My question is if I regeared to 4.10 would this help the power and gas mileage? The gas mileage can't get any worse anyway!

Thanks for the help!!!

 

depending on tire size, 4.10's could hurt gas mileage, because your rpm's would be running higher at cruising speeds. are you sure you haave a 3.00 gear ratio? what rearend do you have?

 

Yup, something else is wrong. 3.55 gears would be better suited for your truck but your lack of any nut and crappy mpg would indicate tune-up or compression issues.

 

You probably have 3.09 gears, they suck for power but aren't too bad for gas milage. Start with a basic tuneup. Is the truck fuel injected? If you i would replace the o2 sensor, those can make the engine run like crap, especially on the early fuel injection systems. For a truck of that age i wouldn't expect more than 15mpg. Most brand new truck i see are only averaging around 19-21mpg.

-Jon

 

Thanks for the help everyone I thought the 3.00 ratio was a little weird to but that is exactly what the build sheet I requested from Ford said? So far I have done the following since I bought it:

1. new spark plugs and wires
2. new O2 sensor
3. new fuel filters
4. new belts
5. new PCV
6. new air filter
7. new Flowmaster exhuast with no cat

Yes, it is also fuel injected.

Anymore suggestions??

Thanks

 

if its still crappy(mpg) I'd look at your cap and rotor. ANd a timing check might be a good thing to check. Maybe a vacuum test, a compression test and maybe a leak down test.

I, personally, would definetly think about 4.10s in a 2x4 pick-up. Once the fuel mileage is straightened out I'd kill it again with the ring and pinion!

 

Thanks for the help I forgot to mention before that I had replaced the distributer cap and rotor button. I am thinking it may be a timing issue. Plus, my clutch is on the way out so this isn't helping any.

I will probably go to the junk yard and find an axle with 4.10's and swap them

Thanks again

 

My idle speed is currently only 500 RPM and whenever I turn on the AC the truck goes down to about 300 RPM and cuts off. I think I'll adjust the timing so I idle around 1000 RPM that way the motor want be bogged down by the AC.

Do you think this will help with the power issue also, especially with throttle response?

thanks