78 supercab F-250 4x4 that's being converted to 1 ton. Soon to have 4:56 gears, currently at like, 4:10. Im not thrilled with the factory 351M: Its big block thirsty and grossly underpowered in the torque dept. I don't wanna dump money into building up a V8 that's only going to get 10 MPG when im done.
Ive seen 240s and 300s in 1/2 ton pickups run forever and pull down respectable mileage.
BUT WOULD YOU USE AN I-6 IN A ONE TON DUMP THAT HAULS STONE, PLOWS SNOW AND PULLS A HEAVY TRAILER?
Im trying to avoid the "gotta have a 460" mentality, I want a little fuel mileage, longevity and ease of maintenance. I need LOTS of torque way down low. Im prepared to BUILD a 300 6......... but only if its up to the task of extreme abuse daily.
The 300 was used for 41 years. It's reliability is about as good as you'll ever get. It's one of those engines you'll hear guys joke about how they went out on a weekend with their buds and tried to blow it up, only to fail. Will it hold up? I'd say yes, but I can't guarantee it. What I will say though is that if there is any engine that will be able to handle that job, it's the 300. It's always been a torquey towing and hauling engine. That's what it was designed for. Ever see a Tug at an airport? That's got a 300 in it.
If I had extra money and time though, I'd throw in a diesel.
The 300 was used for decades for lots of applications where it ran all day long at high RPM. Almost all UPS trucks had them for many years. Wood chippers, ski lifts, irrigation pumps, etc. etc. It's not going to be fast, but it's made to work.
I rebuilt my 400M with an RV cam. I had awesome power. I had awful gas mileage. My neighbor had a 300 six and his wife drove the family 351. The guy was always complaining about the 351's gas mileage. just sayin'
Like several have mentioned before...the 300 was built to work. Its easily maintained, easy to tear down and build, and will outlast most anything running. There is a reason it lasted from 1965 thru 1996. Lets be honest, mileage simply isnt a primary variable when hauling huge loads like described above unless you apply forced induction and/or diesel power. However, the 4.9L will keep going when most will leave you stranded. Seven main bearings, long stroke with inherent low end torque, and as long as you're not building a hot rod...fair mpg with careful maintenance and a good tune. Cant go wrong with an inline for a work truck man. Hope you're as happy with yours as we are if/when you do the swap.