In 1971, before SAE "net" power measurements, the 400 was rated at 260 hp @ 4400 rpm. By comparison, in 1971 the 460 was rated at 365 hp @ 4600 rpm. Bear in mind that these numbers compare a 400 with a 2V carburetor and 9.0:1 compression ratio to a 460 with a 4V carburetor and 10.5:1 compression ratio.via internet

 

The 351M was a simple, de-stroked adaptation of the 400. It uses the same block as the 400 with a shorter stroke crankshaft (3.50"), the same M-block connecting rods, and a unique piston with a taller compression height to compensate for the shorter stroke with the same rods in the same block. In fact, the only difference between the 351M and 400 is the crankshaft and pistons. All other components are the same. In practice, Ford did use slightly different components in the 351M and 400 for different applications and for performance reasons, such as camshafts, timing sets, and valve springs, but functionally, the engines were identical except for crankshafts and pistons. The 351M's unique piston was a dished type that produced 8.0:1 compression.
see, 351 ms are the ones with the dished pistons glad to help

 

In '72, not only did they switch from gross hp (at the flywheel) to net hp (at the rear wheels with accessories attached), but the 400 also had its compression ratio dropped from 9.1:1 to 8.4:1, and in 73, they retarded the cam timing to meet emissions standards. In '77, they were put into pickups and the ratio stayed at 8.4 for the rest of the run until '82, when it was phased out. 175hp with a 400 doesn't really surprise me (2v carb, emissions standards, poor compression ratio, retarded cam timing, and crude emission equipment).

351m had in the ballpark of 160hp for it's whole run from '75 up until '82, when it was also phased out.

So yes, 175hp sounds about right to me. I've been studying all this info myself for when I do my 400 build, but I was lucky enough to find a '71 400 with flat topped pistons and straight up cam timing.

The "goes like hell" feeling you get from your truck isn't the hp you feel, but instead, the torque. Torque is what you need in these lead bricks to get them going at a decent pace. Keep them in the torque band and they do indeed go like hell.

 

well sorry i love both my pickups and my 77 is a torque monster just wish i had another gear in the tranny even with 3:55 gears

 

Yeah I know both those feelings. My 77's only got the 351m in it, but it's still decently torquey. Could use a 5th gear though. She's revving pretty good to go 60.

Also, I wasn't trying to knock you down, I was just trying to state facts. No harm meant, I apologize if I came off as snobby. No hard feelings, yeah?

 

no same way with me and thanks for the education and what rear end yuo got mine goes about seventy tops and thats wrappin pretty tight and plus i can start off in 3rd so maybe time to put the 3:08 rear end i got on hand with a posi tract lol

 

Haha nice dude. I got the 3.55's in mine. I got it up to 80 once upon a time, but haven't been able to repeat the results. The 351m will scream a little bit more than the 400 will, but not a whole hell of a lot. The carb was tuned in perfectly that day, a little bit colder weather (about 45° maybe 50). Everyone in town said I was pretty brave for driving a lifted 4x4 with bald 33's that fast lol

 

ya same in mine.. a limited slip but yours is pirdier than mine mine is just a good old work truck hand me down from my grandpa 2wd used to pull gravity grain trailers i wanna upgrade to a edelbrock thunder series but then i would get even less mpg but oh well

 

Ah, yeah mine was a hand me down, too. Had a 78, but my old man told me to give up on it and fix his old truck. I put a new trans and t-case in it, along with tires, springs (I lifted it when I was 17), exhaust, driveshafts, etc. He handed me the keys and told me it was mine, then! It looks pretty, but I abuse it. I haul wood with it, I offroad with it, I beat on it like it was gonna go to the scrappers tomorrow haha. It's no tar baby, that's for sure! I got dents and broken mirrors to prove it.

As for the edelbrock, you'll lose a little bottom end and gain up top, so that 70 may turn into 80 or 90 haha. And mpg's, I gave up hope on that a long time ago and bought a 2wd Ranger lol.

 

Manm, that's bad. My 89 Ranger would top in at 115 when new. Take your stock 77 400, swap the cam to a 204/214* .484/.510 lift cam, swap out the Autolite 2 bbl for a Holley 500, add headers and it'll top in at well over 100 without breakin a sweat. As for those retarded timing sets, I've yet to actually see one. The cams were ground with the retarded timing.

 

My 77 doesn't have a 400 (yet) but I wouldn't leave a motor with that much potential stock.

I'm not looking to break 100 with mine. I want a torquey motor, not a fast one.

 

yes i want torque i dont need to go even seventy with a load so all i want pretty much is torque and it has a holley 2 barrel on it now but being i can start off in third i think i need to put that higher geared rear end in it. and as for my grandpa, it was pretty much the same story, my uncle wanted to get rid of it and junk it and i couldnt let that happen..too much sentimental value. so my grandpa said here take it home with you lol and i love her and she starts up in -3 days (at least thats the coldest i tried it to) and fires right up(with the exception that the choke is on) and ya basically if i had another gear or higher gears thats all i need to go faster but i want TORQUE

 

Y'all are a bit confused as to the role of torque. If you have the torque to do what you think you want it to do, the top speed will be there too. HP is simply a derivative of torque x rpm. The 08 Pete I drive is rated at 260 hp, but it'll still do 80 mph with a full load (54,000 pounds) It's got 700-800 ft lbs of torque.

 

you realize i am talking how fast i have had it going and i stop when i think i am revving it too much im sure if i had another gear i could get as fast as i want or higher speed rear end.... do you get what i am saying

 

Unless you have a tach on it, how do you know it's reving too much ? What's the rear gear ratio and what diameter tires are on it ?