Like the title says i swapped in a roller 351 in place of my 300 in my 93 f150 single cab short bed 4x4 zf im not really impressed with its power. I mean anything under 2k rpm is a joke compared to 4.9 but when it comes alive around 2500 rpm its much faster but i really expected more it has long tube headers dual 2.5 inch exhaust do i have something wrong or was i expecting to much? Im new to the v8 s but my brothers 302 impressed me

 

if you have it properly tuned then i have to think that you swapped in a tired 351 ???
until just recently i owned both a 300 and a 351 and while the 300 was a good little mule, the 351 was better in every way except mpg, and even there it was close. not a night and day difference, but definitely noticeable.

 

A long time ago, I did this swap in the other direction. Replaced a 351W with a 300 six. Found the towing capability was pretty comparable, but killed any hope of exceeding 70 mph. All this was in an E150 van. Originally was a 302, so I had the advantage of driving all 3 engines in the same chassis. 302 just did not compare favorably.

Bore on the 300 and the 351 is the same at 4.00. Stroke on the 351 is 3.5 and 3.98 on the six. Mechanical advantage favours the six, but the extra two cylinder give you around 325 ft lbs torque with the 351W vs the 260 ft lbs for a 300 six. If you are feeling a difference in favour of the 300 six, there's something not right.

 

What have you set the timing to and did you remove the spout plug to set the base timing? That things should be able to peel rubber from idle so you got something messed up.

 

When I was selling new Fords everyone who was driving a GM truck would tell me the 351's were dogs compared to the 350's they were used to after a test drive. I think the "tune" that Ford put into the ECM didn't favor off the line snap.

I've owned two 351's… one in an E350 and another in an F150 SC. Both performed well but neither would snap your neck from a stop light.

Try bumping up the timing a bit… that may help it feel a little better.

 

It wasn't the tune holding these motors back it's the badly undersized heads and intakes these motors got along with smog era cam grinds. You can pull any old 350 out of a junkyard, swap in a cam and bolt on a 4bbl and headers and have a 350hp motor, do the same with a 351 and you might get 260hp.

 

The engine has 44,000 miles and fresh heads (stock) and 2nd gear in the zf let off clutch at 1500 rpm it will smoke tires but towing 3 k was really weak and 5th gear empty at 45 mph wont do any kind of incline where my 300 hardly comes out of 5th for any reason. Yes the 351 will smoke the 4.9 but thats not how i judge torque

 

What is the timing at?

 

Timing should be stock as far as i kno i havent touched it but i am gonna cam it just confused on what cam to run in a sd roller motor

 

Is it a stock motor? Almost sounds like it has an after market cam that doesn't make its power in the low rpm range. Gearing has a lot to do with this also to tall and they have no pull in the low end.

 

It has 3.55 gears and 33 inch tires i swapped stock tires on it and it was faster but in 5th its still a dog

 

It's all about running in the power curve. 5th gear overdrive is usually a dog unless you are really already up there in speed. You said 2500 rpm is where the power comes on. Then that's where you need to be. Use the shifter don't just lug it along. And yes check the timing I have seen ford trucks that weren't timed right from the factory. The two 351 trucks I have had with 3.55 gears where doggy. One I put a 4.56 gear set in and it was like a new truck. And didn't hurt mpg's enough to notice.

 

Get a timing light and have a look, you can borrow one from a parts store usually if you don't own one. Your description of the engines power makes it sound like you have a 5.0 not a 5.8, are you 100% sure you don't have a 5.0?

 

Yes its 5.8 out of 94 f250 4x4 and i under stand power curve but the reason i swapped is i was told by many on here the 351 is the best of both worlds between a 4.9 and 5.0 and it is not showing me that? It has more power than a 5.0 every where but like i said under 2500 is maybe half of my 4.9 ill throw my timing light on it when i get time

 

If it's less powerful that a 4.9 it's broken.

Until you get rid of the stock e7 heads it will be a turd no matter what you do. Heads, cam, long tubes and it'll move.