While cruizing through the boneyard today I came upon a NICE 1978 F250 XLT supercab that had just been brought in. It almost made me heartsick to see this truck sitting there as it is in far better condition than most I've seen on the road lately! Metallic blue with clearcoat! Body straight as an arrow with very minimal rust which is extraordinary around here. Looking under the hood, it looked like the owner had steam cleaned the engine well not that long ago. I looked at the block and it looks about the same size as my 460 but couldn't be sure. I didn't think about looking at the carb to see if it was 2 or 4 bbl until I left. I know that most 400's are a 2 bbl but I was just curious if there is a way to tell the difference visually? I'm sure there is but as I'm more of a body guy and less of an engine guy I'd throw this out to the guys that know much more than me! I just can't figure why someone would kick this beauty into the graveyard! I'll try to get some pictures up later.

 

A 400 should definitley look smaller than a 460. A 400 is in the 335 family (SBF) and the 460 is in the 385 family (BBF). IIRC, a 351m/400 will have 8 valve cover bolts and a 460 will have 7 bolts.

A 400 will have a dry intake, and 460 will have a wet.

Save what you can off the truck!! And post up some pics!

 

351m/400 = 8 capscrews for the valve covers, 7 for the 429/460 as per prior post.

351m/400 will be as tall as a 460, but shorter.

460:

Big-Block Ford 460 Engine Build | Car Craft Magazine Article at Automotive.com

You can see the front of the manifold per prior post:

Google Image Result for http://www.fordification.com/galleries/albums/userpics/10045/95motor.jpg

351m/400:
TMeyer, Inc. Precision Automotive Machining

Note the water intake hole ahead of where the manifold will rest.

 

351M and 400 the manifold bolts are at an angle

429 and 460 the manifold bolts are in a straight line BUT the 429 was stopped being made in 71 or 72 as i recall you, so if the block number is D3-D9 its not a 429, this number is above the starter

 

351M/400 the top water neck bolts to the top of the block in front of the manifold.

429/460 it bolts to the "wet" intake.

 

The 429 continued to be produced into the 80's, but was only used in F600 and higher trucks, as did the "baby" of the family, the 370.


But yeah, look where the T-stat housing is. Bolted to the top of the block with verticle bolts, 351M/400. Bolted to the front of the intake, 429/460.

 

Some good tips listed here, a few more:
351M-400 have a flat thin steel timing cover between the water pump and block, 429-460 has an cast aluminum cover, approx 1 1/2" thick.
On a 351M-400, the fuel pump bolts to the block with a vertical 2 bolt pattern, a 429-460 fuel pump is attatched to the aluminum timing cover, with a horizontal 2 bolt pattern.
From the factory, ALL 351M-400s had 2 barrel carbs, all carburated 460`s were 4 barrel, although some early 70-72(?) 429`s were available with a 2 barrel.

 

Thanks for the great tips guys! I was able to determine that it was a stock 400 with a 2 bbl carb. The unfortunate thing is, by the time I was able to make it back out to the yard, the truck had already been pretty well ravaged (by somebody that didn't have a clue..or care)! They didn't seem to care about the way to get what they wanted and they made a mess of it. The pristine tailgate was gone (no rust or dents either side, latch mechanism was crisp!!!) but instead of just lifting it out, it was like they used a crowbar and just reefed away at the corners, destroying the taillight lenses & chrome...rear windows were cracked, upholstery on the rear bench was torn and had holes, front grill had been smashed, tossed an alternator onto what previously had been a rust-free, scratch-free hood, all this was in near perfect condition earlier...and apparently they didn't know about the right way to remove the racetrack trim on the bed as they just pulled and pulled on it thinking it would just "pop" off!! Needless to say, they made the whole thing unusable and really ruined a beautiful truck! I managed to get the air cleaner, one bedside trim, wiring sockets & lenses & a few interior components that weren't broke & the carb but there could have been so much more! I don't understand why some people just have go like Sherman's march thru Georgia to get what they need...I mean if they need it to replace something they have...you'd think they would know how to get it!!