i have a 73 f100 with a 77 400 in it and i was woundering if anyone could tell me what these motors put out stock

 

They were rated at about 168 horsepower.

 

actually 158 HP which I posted in the post that got removed for some reason


This HP rating was at the wheels though and not at the back of the crank like old rating were

 

These were still rated at the crank, not rear wheel HP. The HP standard changed in '71 or '72 and required little things like aircleaners, PS pump/other accessories, stock exhaust manifolds and mufflers. These were called "net" HP ratings, vs. the old "gross" rating without accessories etc.

http://www.hardtail.com/techtips/hpexplained.html

http://www.motorera.com/dictionary/SA.HTM

 

Okay thanks.
I thought that method changed in 1975/76.

 

Regardless, its pretty dismal for all of these motors. HP didn't really jump into good numbers until the late 90s with the Modular motors.


However, you add a little compression and all these motors really wake up.

 

well my motor must have someting done to it cause it will run with a mitusbishi 3000 gt thats rated at 320 hp and it will also run with the new dodge hemis no problem

 

The Net Horsepower ratings began in 1972. 85e150 is correct in his description of the difference in those ratings and the previous measuring methods.

The horsepower ratings of these engines can be deceiving. These engines make a reasonable amount of torque. Horsepower is a mathematical calculation which is greatly effected if the torque peak is at a higher RPM. The torque peak of these engines is in the area of 2,200 RPM, so mathematically this produces very little horsepower. A modern 4.6 makes approximately the same torque but at twice the RPM, thus producing much more horsepower.

Lots of torque at low RPM is not a bad thing for street driving. Lots of horsepower is absolutely mandatory for drag racing.

My F150 4X4 that weighs who knows what, is propelled along pretty respectably with a very slightly modified 400. If I were to expect the same pulling power out of a 4.6 with almost twice the horsepower, I would have to use MUCH lower (higher numerically) gears.

As a previous poster in this thread indicated, the downfall of the 400 is lack of compression ratio. Coincidentally, these engines were produced during the low compression era. The heads flow very well and everything else works together pretty well, but the lack of compression keeps them from coming alive.

There are MANY solutions for raising the compression and waking up these engines that can be read in the forum covering the 351M/400. Now that I said all this, I will point out that the forum police will be along soon and chase this discussion to that forum.

 

ford allways underated hp, but if you put a aftermarket intake and a 600/650cfm carb on it it will do pretty well.

 

They didn't under rate the horsepower, the motors really didn't make much horsepower, but trucks operate on torque, and all of the ford motors of that era make plenty of torque.

 

your right that ford motors made plenty of torque, but ford did always underate hp, they did it for insurance reasons, fact not a lie.

 

Torque rating on the 400

In 78/79's the rating was between 260-276 Ft Lbs at 2000 rpm

 

It actually is pretty sad that this 4 inch stroke engine has such a small amount of torque. I blame most of that on the fact that it has such a low compression ratio.

 

Stock compression is about 8.2:1 and makes about 160HP and 260ft/lbs, bump that compression up to 9.5:1 and I'm making 365 HP and 435 ft/lbs. I'm still running pump gas, albeit premium 91 octane.

 

One guy on FTE has a 700 HP 400 he says.