I have a 1994 f150 4x2 with a m5od and 2.73 rear end. I have had this truck for around 3 and a half years. I like the truck, but it doesnt have a lot of power(im pretty sure some of the international 4300's at work are faster empty.)

I was wondering if swapping the 300 for 351 w would be worth it and what parts i would need to do it.

From reading this site im figuring i would need the following things.

1.) a running EFI 351 w
2.) a C-6 or ZF 5spd with a small block bellhousing
3.) a lower geared rear end, like around 3.55.
4.) a computer for the 351 w/ manaual
5.) many various misc. parts

My questions are
1.) would my current driveshaft and trans mount location work with either a 351 z-f or 351 c-6 combo?

2.) would any welding or modifications be required to the motor mounts?

3.) would i need to upgrade the front coils? current front GAWR=2650

4.) how much does a good 351 cost?

5.) is a c6 or zf cheaper

6.) Would i need to change fuel pumps for a 351. Also what is a good brand of fuel pump to get regardless if i need to change them or not. (im gonna replace one of mine w/ a leaky gas tank this summer no matter what.)

7.) Do y'all think this would be worth it or just end up being an expensive waste of time?

8.) i know some of yall are thinking, why not just sell the thing and buy one w/ a 351 already in it?? my answer there i that my truck is a northern truck w/ rust over the wheel wells and behind the driver side cab corner, so i wouldnt beable to get hardly any $ for it. But, it will hopefully last me several more years if i do nothing because as of now it only has 71000 miles on it.



thanks for responding this here long post.

 

The 5.8 and 4.9 are good motors, both very good truck motors, but swapping to the 5.8 won't be a simple. Your biggest problem is those gears, they need to go no matter what motor is in there, so I say find a junkyard rearend with 3.55's, rebuild it with new seals and bearings, bolt it up under the truck and call it a day. The difference this will make to the vehicle cannot be understated, Ford should be slapped up side of their corporate heads for putting this gear ratio in a truck!

 

along with the parts you mentiond for the motor (computer and harness) You can buy motor mounts that will bolt in to the frame and then just drop in the 351. You can also just bolt up your M50D it will work fine I have one in my 1990 Extended cab 4x4 with a 351. the 2.73 gears are good fuel milage gears, that is why ford put them in the trucks. they are not great for power and put lots of extra strain on the tranny due to the amount of torque required to turn it. upgrading to 3.55s would be a good idea.

 

Having owned both 300's and 351's I can say that this swap is going to be a big waste of time. There just isn't that much of a difference between these two motors. You'd think the extra cubes would make a difference but they really don't. The 351 will beat the 300 in a race, but if you put 5000 lbs behind each one, there is virtually no difference.

As Paul said, the gears are what's holding you back. Swap them out for 3.55's and you'll think you put a 460 under the hood.

 

I do agree with you guys

just answering his questions.