I have a 1992 Ford F-250 4x4 w/a 5.8l blocked 408ci stroker attached to a ZF 5 speed tranny running 3.55 gears. On the engine sits a set of 64cc chambered, 190cc intake runner, 70cc exhaust runner, 2.02 intake/1.60 exhaust heads (which given the stroke, bore, and pistons, it has roughly 10.2:1cr), and an Edelbrock Performer truck intake. So far that's as far as I've gone.

Now, when this engine was just a .030 over bored 351/357ci engine I was running a Comp Cams 35-255-5 cam, but, considering that I'm swapping the computer out with a mass air computer, adding the mass air meter, and installing a Moates Quarterhorse in it, I'm thinking a slightly bigger cam would be nice, but I'm not sure since the valves in the heads are good sized and I'm considering going with link bar roller lifters, which even on the cam that I have now it would increase the lift some, and this is a 4x4 truck motor. That's why I threw in the tranny and gear info, I'm hoping that someone who actually builds performance 4x4/everyday drivers that will both pull a decent amount of weight like a truck should, yet be fun to drive on the street and be able to power out of mud holes with ease like a 4x4 should, will decide to read this and have personal experience building a beast like mine and decide to respond.

My 3.55 gear is optional as well. I have a rear axle that I'm planning on putting in that's out of a 1 ton dually. It's 4" wider, 2" per side, so using it will space my back tires out as wide as the front, and it's got 4.10's in it, and since I'll also be solid axling the front in the near future, I can go 3.55's or 4.10's.

So, wether I roller cam it or not, should I go with a slightly bigger cam, or maybe even a slightly longer duration or overlap or should I stick with something close to what I've got? My thinking is that maybe I should go for a little more air in and out, and whatever I lose in low end torque will be made up for at about 2500-3000 rpm's or so. When it was just a 357 it had so much low end torque that on dry pavement you couldn't take off without it barking the tires unless you let off the clutch without touching the gas. It doesn't have a neutral start switch in it because it used to be an automatic and I eliminated it when I swapped trannys because I didn't have the stuff to put it in. Anyway, right after I built the 357 I was goofing around and not paying attention that my son had got in it and he just barely turned the key and the truck fired up and plowed into my house, but, it had so much torque that hitting the house didn't shut it down, it was sitting there wheel hopping the back tires trying to push the house over, at idle, nobody touching the gas, my son was like 7 or 8 at the time and couldn't possibly touch the gas.

Now, in my opinion, a pickup truck needs a lot of torque, but that's insane when at idle your truck is trying to push your house over by itself. I also used it one day to pull a shed, and, a Ford 3500 tractor, around my uncles yard. He tried to move the shed with his tractor and it just buried to the gear box in his yard. He couldn't get away from the shed with the tractor, so I had to pull at an angle. The first thing that happened after I hooked to his tractor that was hooked to the shed is that I barely touched the gas and took off and pulled the tractor and shed about 8' before I almost pulled the tractor over on it's side. When I realigned and hooked on I drug both the tractor and shed all the way across his yard to where he wanted it, and the shed was just being drug on the 4x4 posts in it's sub floor, it didn't have wheels or anything, and the shed was full of shit top to bottom.

So, long story short, I don't think I need that kind of low end torque. I think that I should allow more air in (and yes, I know that I need new injectors, I rough figured about 32lb injectors, that based on a 408 build that some hot rod magazine built using almost identical heads and the same cam that I've already got, they dyno'ed it, and it put out 475 torque with 390 hp, all power peaks in the right areas for my truck build also, and on a website fuel injector calculator it came out 30lb injectors would just barely cover it so I decided 32lb injectors since I might tweak my hp/torque curves some with the Quarterhorse and you can always tune fuel down some if needed, but it's real hard to get more fuel than what the equipment will spray no matter how bad you need it, plus it seems like the mass air would adjust that also.

Anyway, that's all the detail that I can think of right now. I'm hoping that some 4x4 truck genius gets on here and can point me in the right direction as far as whether I should get a bigger cam, keep my cam (if I decide to go roller cam then should I stay about the same cam specs or bump up some, the cam I have now, which only has about 20,000 miles on it, the specs are .478 intake/.485 exhaust, duration @ .050 is 210 intake/214 exhaust, 114 degree lobe separation), whether my calculations of the fuel injectors seems right, and honestly and basically whether I should build this engine to have it's hp peak a little higher in the rev range and make up for it with the 4.10 gears or keep the hp peak about the same and stick with the 3.55's.

Anyway, thanks in advance, hopefully somebody reads this that knows all the details that I'm a little iffy on and can straighten me out on this. The only thing really that's throwing me off is that I'm used to building cars that weigh 3,000 lbs, not a truck that weighs 5,000, that and, well, it's good on a car to be able to boil the tires, it gives you better traction, but trucks are exactly the opposite, especially if it's a 4x4, there has to be at least the take off range where it doesn't slip the tires everytime I take off, and my tires aren't slick, they're fairly new mud and snow tires with decent sized lugs on them, but my truck pulls itself at idle from a dead stop, hell, it's in overdrive when I'm cruising town at 30 mph idling, so in my honest opinion I think it's got enough low end torque, I feel I should be trying to boost its torque in about the 2500 to 3000 rpm range, but that's why I posted this, to see what other fairly well educated gear heads thought.

  • 1
    This is quite a book ... reading through it, I'm wondering ... what exactly is your question? – Pᴀᴜʟsᴛᴇʀ2 Dec 29 '16 at 16:14
  • I kind of think you're answered your own question – if I'm understanding everything, you've got too much low end torque, so it would be good to trade some of that for a wider torque band. Do you know how to estimate how much torque you do need/want at the low end? (I don't.) – dlu Dec 29 '16 at 18:22

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