I am going to buy a 74 F-100 with a 390 in it. It already has headers on it. I was wondering what the horsepower and torque would be

 

pretty vague...

 

It is basically a stock motor

 

I think stock they're around 200hp and 376ft lb torque @ 2600 rpms. I understand headers really wake up FE engines as their exhaust manifolds are really restrictive. I'm not sure how much more power it has but would guess around 15 to 25 hp extra w/ headers depending on exhaust setup...

"8.6:1 — 201 hp net (150 kW) at 4000 rpm and 376 ft·lbf net (510 N·m) at 2600 rpm

* 1972-1975 Trucks"

http://www.answers.com/topic/ford-fe...cat=technology

 

Does anyone know what that would work out to as far as grossHP approx.?

 

I think the 390 is rated at 255hp and 376 lb/ft stock.

 

The 255 is pre-72. Post-72 there were no gross horsepower ratings anymore, just net.

 

Excluding design, nothing post '71 was too exciting. The engine foundation to build on remained fundamentally unchanged except that lazy cams and dished pistons were the order of the day. Other important parts, like ignition systems, had improved, but power levels continued to sink to new lows. I'd be surprised if your 390 was anywhere near 255 hp in '74, maybe 195hp with 320fp torque. Late model FEs were heavy and slow, but there's hope buried beneath those dirty valve covers.

 

That is probably true but here is the thing. I recently sold my 2000 F150 4.6 5 speed that was only 3875lbs and bought a 74 F250 390 C6 with headers and this 74 feels a LOT stronger. The F150 was 220hp 290 torque and it does not hold a candle to this 74. The 74 does have lower gears but it also has 33" tires.