81 F150 Tach Install

[Raywilson]

I've got a 302 AT and don't push it very hard, best I've done is 11mpg. Full size Ranger. 2- 20gal tanks

[Gary Lewis]

Raywilson wrote

I've got a 302 AT and don't push it very hard, best I've done is 11mpg. Full size Ranger. 2- 20gal tanks

Yikes!  I can get that consistently with Big Blue at 65 MPH on cruise, and can get 12 feeding it manually.  I think you may have a bit of MPG left on the table.

[Raywilson]

I've only had it around town, never a road trip. Not yet anyway. Has the AOD transmission, so hiway might/should be better.

[ArdWrknTrk]

Oh, how I wish that was true for me!

[Gary Lewis]

Ray - I don't measure it around town, but I'm sure it would be far worse than 11.

Jim - I'm a grandpa and drive like one.  

[ArdWrknTrk]

And , I'm a lunatic.  

[mat in tn]

I'm also a grandpa and I too drive like one. however, I don't think all grandpas drive the same
my 81-camper special with the 351m gets better than you are getting. not much mind you. but I'm getting 15 easily around town and 19 is achievable over the road from my 93 flare side. not the same I know but volume times rpm is. I feel you are not tuned to full potential.

[Raywilson]

Grandpa's all around! I'm 73. Everything seems to running fine, starts instantly. No fumes.  I have a friend who has a 70s Sun Tune-up "computer". He's a carb specialist as well. Goes by Henry the Carb Guy. I'll give him a call...
Ray

[mat in tn]

being a trailer special I'm guessing it has the c6 and probably a 3.00 gear. not the best for either around town or highway but a fair compromise nonetheless. there is a real reason for the advent of the overdrive in f150 trucks however I expect you should be able to get 13-14 if tuned right.

[Raywilson]

It has automatic overdrive transmission. Maybe the vin will tell me the rear gear ratio

[Raywilson]

3.25 ratio- hwy gearing. That explains my poor intown mileage

[mat in tn]

3.25 with an od? I'm guessing it's an aod (metric) with the early kick down rod for tv control.  I don't know much about another option. the majority of the aod's were paired with the 3.55 gear in 8.8 or 3.50 in 9". I'm running 3.73 in my flare side and it's my best mpg truck. l am very interested in other combinations as I am always trying something new. I am building one with a 5.0 carb and an aod with a 3.31 currently. this is fairly close in final drive ratio to yours.

[Raywilson]

Yes, AOD. On Gary's rear axle chart, my VIN shows I have a 15 axle ratio or a 3.25 ratio. Not great milage about town.

[mat in tn]

oddly enough its possibly not good on the highway either as you likely are turning too slow for efficiency and in 1981 I don't think the 302 had more than 145 hp. and hp is not achieved at low speeds. it is counterintuitive yet when the engine is allowed to spin a little faster and easier yet a bit lean, the mpg can go up. with an aod ,the od is the deepest in these trucks at .67   meaning your final drive is 2.18.  2.5 seems to be the sweet spot from my experience. it would take a 3.73 to achieve this in your truck. if you were looking to have a bit more feel of power you could go with 4.10 but that will possibly go past peak mpg and start drinking again. but tow a trailer it will do!
in 1981 the national speed limit off 55 was still in effect and ford was engineering. these to be practically coasting I believe. now with everything including econo box cars going 80 on the interstate you are going to need to stay on the throttle a little bit and keep power being made, but I'm rarely on the throttle as much as 1/8". some trucks I just "feel" the pedal.

[Raywilson]

Pics of my new and old dash replacements. My old one has a white cable going to the steering column. New one does not and doesn't have way to connect. What should I do?

[Raywilson]

Thank you for the information, that's really helpful. I'll look for a 373 ratio you recommended. I see the 373 is a 1986 part. Is it physically interchangeable w my 81?
Ray

[Gary Lewis]

The part the white cable goes to is held on with a couple of screws.  So you can move it to the new instrument panel.

[BigBrother-84]

Yep, this part can be transferred from a cluster to another.

Be careful.  I don’t have a three on tree, but I heard this cable could be somehow fragile.

Am I right, guys?

[Gary Lewis]

That cable is for an automatic transmission's gear display.  And yes, it is very fragile.

[Raywilson]

Thanks for the description of what it's for.  Hope it'll reconnect to the new one