Conversion,,,, backwards,,,,,

[Docmodisett]

I have a 1985 F-150 swb with the first year EFI in it,,, Bought the truck 6 years ago right out of a junk yard, for $600,,,, love it,,,, but cant get over 14 mpg out of it, no matter what I try and If I do say so myself, I do know some tricks,,, been at it for a while now,,,, I intend to give the truck one last chance to come around,,,,, What I have in mind is taking the 302 to a carb set up,,,, edelbrock performer intake, single 4 manifold, vacume advance distributer, stock Ford ign...cold air pkg.... and a holley 600 cfm carb....
I I remember when i had a 312 Yblock that would get 20 mpg all day long on the road and now this 302 with all the complex, computer powered crapola will not get over 14 mpg..... I am tired of messing with it....and,,,,, Question is , what exactly do I have to do to accomplish this swap????? if after I do all this,, it still dont get decent mileage , i have a 401 Nailhead buick engine and trans in my shop that will get 18-19 all day long and have bunches of torque..... i will make a Buford out of it....

 

[wizzard351]

heck if i had a 401 just laying around i wouldnt even think about messin with the 302! if you do carb the 302 its pretty easy,just go old school with the carb and intake. the ignition is simple to just hook up a duraspark from late 70's or early 80's truck. gets a lil tricky when it comes to the feul pump tho,its in the tank and runs a lil more psi then a carb wants,so either wire it to "key on" and put a regulater on it,or pull the pump and make it non working "dummy" that either a machanical pump or aftermarket electric can pump gas threw

 

[Lost]

14 MPG is not bad at all . Even the MAF equipped 302 trucks r lucky to get 16 MPG for the most part . Its you truck and do what your happy with .

Tires and gears can effect MPG to . If truck is a 4x2 may have high gears . So bigger tires or smaller ones (+ - RPMS ) can effect things

As for going to carb .

Been there done that .. Several times as a matter of fact . For the cost of swap could buy allot of gas . But after all the cam swaps, intake, time the MPG increase was not that great .

Cant compare a non emissions motor to one that is MPG wise. You pushing a brick after all. Was that Nail head in a truck or car ? Big difference .That 302 will get mid 20's in a Crown vic.

But if no codes and all the injectors ,and sensors r cleaned , I can see your point . I have averaged about 14 15 in any 302 auto truck I had unless was out west on the flat . And those had over drive auto in them . 3:55 rears

Try a hipo tune up ,good wires 8mm or better ,hipo coil , pull codes, set timing around 12-15* and see if helps . If not the stock 225- 235 75 15 tire try them a couple days .When I run my 31's I lose 1+ Mile per gallon . Free up exhaust .

What ever you do will love to see conversion or other outcome. Nothing sounds as good as a 4 barrel carb kicking open ,

Good luck

 

[Docmodisett]

The rear gear is a 3.08 locker, the tires are all just ordinary tires, no over size.... truck does have air, and a rebuilt c6....4x2....swb.... exhaust system is custom 2 1/4'' single system that has a muffler that I built with 2 1/4'' inlets and outlets and the tail pipe is 2 1/4'' .....msd 6A ign....ho cam....forged pistons...completely rebuilt engine with everything and I do mean everything replaced....all sealed power, trw, melling,,,, ect....done by me....
Lost,,,, I already have the ebrock intake and a good little 600 ''shoebox '' carb....
Wizz, It's worse than that, since I retired, I have been rebuilding vintage Buicks.... i have two 401's, and three 425's with transmissions in my shop... just getting a little old to be rolling around under the truck doing a complete swap.... but if I have to , I will....It would be a little wierd to have a 85 Ford swb that will absolutely fry the rear tires....and looks like a farm truck,,,heck, it is a farm truck....
I love that old truck , it aint fancy, l aint fancy, we make a pair....
Let's see, change intake, carb, dist to early 80s dura spark,,, now what about that blasted computer and the wiring harness?????
Junk yard here I come.....

 

[SuperCab]

14mpg is better than i'd expect out of your current setup...

 

[FordF-SuperDuty]

Don't go cold air, it's snake oil.

 

[1985 Ford F-150]

I got the same thing but a longbed 4x4 with 3.50s, 31s and a 4speed and mine will get around 16 or 17 if I keep my foot out of it. I have 3inch single exhaust and a good flowin muffler. Motors bored .030 over with 10:1 flat top pistons and a 268H RV cam.

 

[Docmodisett]

If i got 17 , I would not be squawking ,,,, but 14 is the highest that I have ever got.... i put new 19lb injecters and a new brain box when I rebuilt it.... i had visions and dreams of getting 20-21 out of it when I was working on it.... WRONG....

 

[1985 Ford F-150]

Might be all your gonna get with an auto. Oh yeah take the belt off the compressor for your ac and itll help.

 

[DNFXDLI]

Don't go cold air, it's snake oil.

Not true...lowering the intake charge temp will help....and to take that one step further, we used to use "cold cans" to chill the fuel as well. Where did you get the idea that cold air does not help?

 

[Docmodisett]

Back in the day ,,,, when I was going to Ford school , they said that cool air going into the carb was worth 8% of the total hp output.... and all the super duty trucks had a hood scoop that picked up outside air.... but the intake manifold still had heat in it.... Actually what I need to know is what I have to do to take the engine to a carb induction...

 

[john112deere]

Not true...lowering the intake charge temp will help....and to take that one step further, we used to use "cold cans" to chill the fuel as well. Where did you get the idea that cold air does not help?

Probably from all the freakin' intakes that pass themselves off as "cold air" but don't do half as good a job at collecting air from outside the engine compartment as modern factory intakes.

 

[Docmodisett]

So,,,, it boils down to intake, carb, early 80's dist, and linkages and fuel lines and fuel supply system.... ????? What about the wiring ?????

 

[86bigred]

my 81 f150 2wd 302 2 bbl 4speed od and 3.00-1 rear.i get 18 mpg regularly,at 85 mph.at 65 mph the rpms are 1600.that c6 is a power robber.i would go with an od trans swap,like a zf.i know a couple of guys that got 3 mpg with the 460 with this change.imo