Hey Guys, it's been awhile since I've posted so forgive me. I've got a 85 F350 4 door dually with a non catalyst 460. Next winter I plan on rebuilding the motor due to I've got a slight cooling leak in the heads (hopefully it makes it that long). My question is what can I do when rebuilding the motor to help the gas mileage? I use my truck to haul my 24 foot enclosed car trailer with my race car to the track. Here's what I have right now, the motor is stock. The only modification I've made is put an Edelbrock carburetor on it, which when not hauling it gets great gas mileage but since I installed it I think it gets worse gas mileage (I haven't had it on a long enough trip yet to check the mileage yet). I still have the original Holley/ Motorcraft carb that works great that I can put back on if needed. It has the original intake, exhaust manifolds, exhaust & so on it. It has 4:11 gears. Should I do a porting of the heads while there off because I've read they could use some help? Should I put in a towing cam? Should I put the original carb back on? What if anything can I do to help the gas mileage? Should I put in a towing converter? It still has the EGR valve on it that still works as well. I know these motors weren't made to get gas mileage & I'm not worried about what it's doing when not hauling because I don't really drive it but to haul the race car. I just thought while I was rebuilding it I would make some modifications if they would help the MPG!

 

I asked similar questions before my rebuild, and the answer was that, within 1-2mpg, there wasn't much I could do to get better gas mileage.

I personally wish I had gone with a 300. I LOVE my 460, but the only reason I built it was to tow cars. Well, first car I towed with the new motor was a big heavy 1980s Mercedes 4 door on a 2600lb trailer, about 200 miles, with a very large change in altitude (had to go up and over the pass)

I never had to go more than 10% throttle the whole trip. Motor is probably perfect for pulling a motor home or large boat, but for a car trailer, I built was too big....

I'm adding a electric fan to mine soon, and I've been told that I can expect 1mpg or so just from that. Picking a cam specific to the RPM range you plan to be in should help too.

 

Handegard, what type of MPG'S are you getting with it now?

 

I really felt like we screwed up the measurements some how, but when I took that long trip, I think my math worked out to 6mpg.

But I've also had a few days where I swear to god I got 15mpg out of the thing.

I'm a bad example though, because my truck has the new motor in it, but I haven't taken it to a local carb specialist to get it tuned yet, and the extent of my tuning is to "make it idle"

And even worse, I have a cooling system problem, my radiator doesn't flow freely, so I had to pop my t-stat out. So I run pretty cold, which should lower my mpgs.

Before the motor swap, I was getting about 8-9mpg, but that was with a almost dead (and in the end, dead) piston. I will be happy to get 12mpg out of the truck, and my ultimate dream would be to one day pull 15mpg with fuel injection and megasquirt.