Hi all from Quebec, kind of newbie question. I bought a 1977 F-250 camper 2X4, 18000 or 118000 miles dont realy know, realy like it ! I try to understand the meaning of 351m/400. My vin number told me I have a 400, last owner tel me he think i'ts a 351, there is a sticker on the right valve cover (8 bolts) with this information: 351M/400 EGR
Engine displacement 400 CID

So I think it's a 400 but wy they write 351M/400 ???
I dont realy care wich one I have but I whant to order the right parts, at Rock Auto for example. Sorry for my bad english, JF

 

The only way to tell for sure is to check the stroke. Pull a spark plug and check tell us what you get. Not sure the measurements but can get them for you.

 

You probably have a 400 if its unmolested. They wrote 351m/400 because that is the engine family. It's from ******* child of the 335 engine family, but still a cleveland. I love em, but then again I love the underdogs like clevelands and mopars.

The only way to know 100% for sure is to pull the number off the crank and see.

 

It says 351/400 because they are of the same family. The only difference between the two is the crank shaft and pistons.

 

So, if I understand, all the parts like starter, intake, spark plugs ect. are the sames, except for the engine internal ?

 

correct you are

 

Absolutely everything is the same, except for pistons and crank and depending on the year, the flywheel. And if you really wanna get into it, carb adjustments. Other than that its the same.

You can't accurately measure the stroke through the spark plug hole due to the angle. Most accurate way to check is look for the number on the crank.

For refrence, a 400 has a 4.00" stroke, a 351M has a 3.50" stroke

 

All the 351M's I have had had a "M" on the top front part of the driver side head buy the valve cover. All the 400's i had didnt. Not sure if this is correct or not..

 

haha just go off your gas mileage! if you get like 6-8, its a 400. if you get 9-12, its probably a 351

 

I've got a '78 with a 400. Its fairly low mileage and in decent shape so I'm not in a hurry to get into the engine. When I do, there is lots that can be done to increase power and efficiency. 50-100% power increase isn't too hard. Stages or steps as I have learned:

1. Cam, timing set and 4 bbl carb. This straightens out retarded cam timing, updates a worn chain and gets it breathing.

2. Rebuild with stock type heads and higher compression piston.

3. Rebuild with closed chamber heads (Austrailian Ford iron heads or aftermarket) and higher compression piston.

TMeyer sells the pistons and other parts needed for upgrades.