So i am thinking about building a 351 w for my 1988 f 150 that has a blown up 5.0 now. Its a long box truck and has 3 55 gears and dual exost 2.5 in out the back. I am tired of playing around with efi and think that a 351w carb will be easyer to work on than a 5.8. Is there a big diffrence in fuel ecomomy between efi and a good carb set up. I am wanting to buy a short block from late model restoration and build it up for daily driver. I want to get as good of fuel milage as posible but i would like a little bit of performance. Like 19 mpg if posible and 300hp or so ? I want to build it right and not have any problems. I was thinking of putting afr heads and a mild/ mid cam in it. Also would this 351 be as good on gas as a 5.0 with headers and duals? My budget is 3500 . Tell me what you think of any of this and if you have build a motor and what worked. Gas is explensive and it would be nice to be able to drive around on as little of gas a posible and still have power.

 

The big question is what transmission does your truck have? If you have an OD trans then the bigger motor will get better highway milage but if not it will be more expensive to feed everywhere all the time.

I had a 5.8 EFI in my truck and it was builtup some with ported heads, a cam, and longtubes. It produced great power from idle up and managed 13mpg city and close to 18mpg highway, but as stated that's mainly because the truck has an OD transmission. Both EFI and carb motors are capable of this kind of milage but I think the EFI version has a better chance of doing it reliably in all seasons.

 

A 351w is a 5.8L.

This can be possible on the highway with 3.55, an OD trans and a strong wind pushing you down a mountain...

With a 5.8L the best you will see usually is 10-13 in the city and 13+ on the highway with an OD trans and 3.55. moving up to 4.10 gears with a stock-like tires size will help in the city, but may cause the mileage to suffer on the highway.

The EFI will be easier to maintain and going from EFI to a carb set up usually costs $1000 or more unless you have a parts truck you can get everything from. And if you have the E4OD then your SOL unless you purchase a stand alone ECU to controll it (another $1000+). So... stick with the EFI and put a cam, LT headers, 1.7RR and heads on it and be done with it. If you use a 94+ (F4TE casting) truck motor just keep that cam and use 1.7 RR and the other parts and you will be in your goal range of 300 hp