Which route did you take when converting it to 4x4? Im currently planning the same project

 

can someone please e mail me on my private e mail and explain to me which motor is ultimately better for heavy hauling I just bought a 75 f250 camper special 2 wheel drive with a 390 and the c6 automatic I have had several 73-9 fords wit the 400m and 4 speed and nothing stands in their way I am not sure about this 390 though e mail me at fivestar.clean@yahoo.com if you wish

 

390 is a great motor.

 

what is the difference in low end torque between the 390 and the 400 will the 390 pull a bob cat

 

With a 4 barrel manifold and some headers 390s are amazing motors. Even stock they are pretty powerfull. Just make sure its a 390 and not a 360

 

well i was told it is a 390 but on the sticker on the valve cover it says 360 390 family i know they are some what similar how can i tell for sure if its a 390

 

Measure the stroke.. 360 will have 3.5 stroke and 390 will have 3.78

 

You can pull a tree out of the ground with a 390 lol. I love fe's. One fersher way to tell a 360 and 390 apat is to measure the stroke.

 

well i am not about to tear the motor apart lol is there any other way to tell like externally??? i know my 400m with a 4 speed would easily pull a skidloader or a car on a trailer at 70mph

 

and what are you calling fe?

 

i also believe that the 400m has much higher capabilities with rpm

 

You dont have to tear it apart. And no the blocks are exctally the same... make sure the piston is all the way down then stick a wooden dowl (or equivalent) down the cylinder then make sure the piston is at the top of the stroke and mark the dowl again and then measure the difference

 

in order to measure the stroke you would have to take the cylinder heads off though correct?

 

hmm i dont know i am assuming being as that it is a camper special and a 3/4 ton it is prob the 390 in my opinion the 360 is junk

 

400 with it's 4" stroke has better bottom end torque. If you put flat top pistons and a modest cam it will pull with most big blocks. I did a roller cam and Edelbrock heads in mine, it will lug along at 450 RPM pulling a 4000# trailer in the mountains. I like it because you can use a lot of 351C parts to make it perform well.

390 is a great engine. Get the compression between 9.5 and 10:1 and you willl have a very strong engine. With your 75? you won't have to make any changes to replace the 360 I would go with the one that is a direct bolt in, both of these engines built right will do what need. In stock form; the 390 will usually out perform the stock 400 with its low 8:1 compression ratio.