So in my search for a new powerplant for my F100 I've come across a deal on a mildly built 400M and C6 trans that I could pick up cheaper than I could build myself. My question is does anyone here have any info on wether or not a 400 will go easily into a 67-72 truck? Have any of you done this swap and are you able to give me specifics on what all is involved? Thanks!

 

Just for future reference (and so you sound like an informed Ford person), there never was a 400M. In the beginning, there was the Ford 400. (1971)
Then, the 400 was de-stroked to make a 351 c.i. engine for cars starting in 1975, and trucks a couple years later. It was called the 351M. The two engines are in the same family, with the only differences being the crank and pistons. If you look closely at the valve cover label, it will say:
Engine family: 351M/400
Engine displacement: 351 c.i.d. (or 400 c.i.d.)
These engines were then produced together for cars and trucks until the early 80's, when they stopped production in trucks (1979 in cars)

 

Thanks, I knew the 400's debut was in 71, and I know all about the differences and such, but I've grown so used to everyone calling the 400 "400M" that it's rubbed off on me. I am very versed in ford engines, but I would say I know the least about parts interchange and what will bolt into what when talking about the cleveland and M family. I know that the cleveland's deck height, a differance of a little over an inch, plus the head design was the major differances between the two, but what I don't know is whether either one will bolt in place of my tired 302 without changing the perches, or wether headers from the 77 1/2-79 2wd trucks will fit in my bump. Plus, I'd really like to hear from someone who has a comparable engine to the one I'm looking at. All I know so far is that it's a 400 with a Lunati bracket master cam, weiand intake, aftermarket timing set to fix the factory retard, headers, and 650 holley. I don't really have any experiance with hopped up M's or 400's so any info would be nice.

 

The 400 has some of the right stuff. It is hard to tell much about it without the cam specs, or the kind of heads, pistons, and compression ratio.

 

He says other than the mods the engine is stock. I'm almost afraid that he may have put too much cam and carb into a low flow, low compression engine, but I'm working on getting some cam specs.

 

The stock heads flow pretty good, but a little work will help. The compression on the other hand is low, and a big cam will not help.

 

351M/400, 302, and 351W/C all will interchange in the same frame perches in 1978/79/80/81/82, etc... That said, if the 78/79 302 motor mount is the same as a 1972 302 motor mount, then a 351M/400 will fit. Only thing is that you need to keep the motor mounts 2wd for a 2wd truck, and 4x4 motor mounts for a 4x4 truck. Pretty simple. The bellhousing on a manual will swap, too, keeping everything in place. The 400 has the big block bell pattern, your 302 is small, of course. An automatic will mean changing trannies, unfortunately.

 

I just checked and the motor mount is the same for my 72 as it is for a 79 302 truck, so the 400 should bolt right in with it's own mounts. Thanks! That answers one question. My truck has a three speed manual currently, so if I bought this engine I would just put the C6 in with it. I know I'll have to figure out something for the trans mount, but thats nothing a drill and correct C6 mount can't cure!

 

Actually, the head design of the 351M and 400 is the same as the Cleveland. You can bolt any Cleveland head onto a 351M or 400. The 2V Cleveland specifically is essentially the same as the 351M/400 head, as they were all 2V. You need a wider intake manfold for the later blocks because of the taller deck height, but there are spacers available to run any Cleveland-designed intake if you so choose.
You need to read this article: https://www.ford-trucks.com/article/...00_Engine.html

Everything you need to know about the 351C, 400, and 351M, and the interchangeable parts between them, like cams, chains, distributor, water pump, etc...
I know you will get great use of this, so be sure to bookmark it, as I'm sure probably everyone here has!

 

Thanks for the link! I suppose head "design" was a poor word choice. I know they interchange, but after 71, from what I've gathered, all the 351M/400 heads were open chamber and clogged up with emissions plumbing.

 

Yeah, the Cleveland 2V were also open chamber. But, in Australia, they did things a little different... They made a de-stroked 351 into a 302, and the heads they used were still 2V, but no longer open chamber, but the desireable quench head. Something we should have had all along, and might have, had it not been for the 'emissions age'.

BTW,
Have you read the link yet?

 

Yes, there is a lot of good info in there. I was just hoping it was going to have a good answer to the piston issue. I really need to find out what year this engine is and go from there. I think I'm going to call the guy tonight and get all the specific details.

 

That's the best thing you can do. To know the year it is is of very little importance. There weren't any significant changes made for performance sake through it's entire production.
But to know what someone else has done is very good info, as long as the source is reliable and knowledgeable. Otherwise, removing the head to see the pistons and the pan to see the crank is your only other option. And the good thing about this, is you will know for sure what you have. Worst case, you will need a head gasket and an intake and oil pan gasket.

 

Usually, unless I get an engine from a very reliable source, I make it a habit of at least taking the pan off and plastigauging the crank to see what kind of shape it's in. If it's not so good, then I'll just plan on a rebuild. If I were really really lucky this motor would be a 71 with 9.0:1 compression, but I'm not counting on that whatsoever. I did just find a fresh longblock 302 on craigslist for $200 obo, so I may jump on it. A torque monster would be fun, but I wouldn't mind putting together a high winding small block either...

 

Ok, so I got some details on the 400. He says it's from a 77 F150 with 40k miles and it's all stock except the intake, cam, and timing set. So it's still got the stock 8.0:1 compression, stock heads and valvetrain, and the timing set was a "performance" set from car quest, so it's probably got the stock 4 degree retard still (which I assume could be fixed by degreeing the cam). He said it's a lunati bracket master II cam, and I can only find one part number for 351c- 351m/400. It's got a duration at .050 of 224 int./234 exh. and a lift of 0.536 int./0.562 exh. Am I crazy, or does this seem awful big for a motor with 8.0:1 compression? And he's got a 650 double pumper on it; does anyone else think it's all a bit overkill? I couldn't ask him because the parts are all new and it's never ran with them yet.