pulling campers

[royrisenger]

I am going to be pulling my 30 foot camper from Texas to Kentucky with my newly aquired 1994 F250 Diesel. Im tring to figure what fuel millage I should expect. The previous owner told me it is a 351M. He also told me the rear end has 456 gears.Also what does the M stand for? Please help [img]/ubbthreads/images/graemlins/shrug.gif[/img]

[fieldtrialer]

I always thought a 351M was a gas engine? M stands for modified. I had one in a '78 ford. The rear end sounds awful low. I had a '94 with 355 rears I thought 410 was the lowest for a F250.

I had a '94 IDI standard trans and 355 rear. I use to pull a horse trailer about the same route you will be taking . Total rig grossed 17,000 and I got around 10 MPG. Same trailer with a 460 gas and 410 rears got 4 to 5 MPG

[Mozz]

The gear ratio doesnt sound right. I was also under the impression that 4:10 was the lowest.

[BJS]

you've got conflicting information a 351M is a gas motor and you're saying its a diesel truck.

mileage in an IDI Diesel or an early PSD w/ is going to run you right around 10-12.

The other possibility for higher gears is if the truck is an Fsuperduty (F450) and then you could have stock higher (numerically) gears than 4.10. If I can remember right you could have something rather close to 5:1 in your rear axle.

It is possible that the original owner towed rahter heavy and replaced the gears with 4.56's to allow for you to start off better which means that you can either slow down or you're going to get worse mileage on the highway.

[SmokeyWren]

[ QUOTE ]
Also what does the M stand for? Please help

[/ QUOTE ]

Here's one explanation I found:

"The “M”, by the way, does not stand for anything. Ford only used the “M” designation to distinguish it from the 351W (Windsor, Ontario engine plant) and the 351C (Cleveland, Ohio engine plant). The “M” designation has now become known to mean “modified” or “Michigan”, even though the 351M was produced at both the Cleveland foundry and Michigan casting center."

But all 3 of those 351 CID engines - "M", "W", and "C" - are gasoline engines from back in the 1970s. Not a diesel in the bunch. [img]/ubbthreads/images/graemlins/shrug.gif[/img]

If your 1994 model is a diesel, then there were three different diesels that model year. You need to post in the '94-'97 forum to know for sure, but my understanding is they were phasing out the IDI, for a while they produced the turbocharged IDI, and finally they came out with the PSD.

Based on the '97 PSD specs, if your pickup is a diesel and has single rear wheels, then it came with either 3.55 or 4.10 rear axle ratio. If it has a different ratio, then it's an aftermarket gear set.