Ok, I am trying to collect information here, nothing is set in stone and it will be a long while before things get to the building stage. Nonetheless early and informed is better than last minute and clueless, so here I am.
Some of you will find this project a little unusual, and may poo poo it, but I find it very interesting. I have had a fast car or two (69 falcon, with 69 351w 4v built to the hilt) and don’t get me wrong I love fast cars and they are thrilling, but pretty hard to make them different than the multitudes. and after awhile there becomes a certan lackluster ability to impress or excite anyone. So I have a project in mind that I think is pretty cool. Someday I hope to Call it the ‘ultimate sleeper’
So I have what would be a ‘survivor’ 1970 ford f-350 1 ton with the 12 foot flatbed on it. (not perfect, but good shape) it has a 360 ci in it right now that I have tuned up to run like new. of course it has no ‘get up and go’, it has the unstopable 5mph crawl.
I plan to fix that. This truck looks like a work truck (in fact… it is). It has the burned off ford turquoise paint on the hood, a bullet hole in the fender, and a chip in the grille. The interior is a step back in time frozen in 1970.
Not something you would think a tire burner. However, that is in fact the plan. I know this truck is a beast at just shy of five thousand pounds, but I would like to make a sleeper out of it. It has plenty of rubber on the road already, so that makes part of the plan.
What would you suggest to do to this truck to make it able to support 850+ hp?
What would be the best route for an engine? a 385 series and spray the heck out of it? what is the best and ‘biggest bang for your buck’ route?
what, if anything, would need to be beefed up in the suspension, frame? would ladder bars be needed?
I am pretty sure that a one piece driveline is a must for that kind of HP? and that the rearend would most likely need to be renforced, but what else would be needed? cluch and gearbox?
thank you very much for any advice.
The rear end may hold up but everything else may be on shaky ground. I’d say go for a 460 and build it up. Lot of cubic inches and they can be found everywhere; often on the cheap.
The driveline will definitely need to be worked. A friend of mine whom I had not seen in a while dropped by my shop late one Fri. afternoon to chat a bit. He was driving a 1-ton Ford truck that belonged to the electrical contracting company he worked for and when he was leaving I yelled at him to get on it a bit as he backed out onto the roadway. (stock truck with duals on the back)
I didn’t think he would do it but he dumped the clutch and threw the driveshaft clean across the street while only leaving about 6" of rubber on the pavement.
That will teach him to listen to me. 
See the post “this truck puts most hot cars to shame”.
Seems to be a popular recent subject matter.
I know, I started that thread.
Anyone have any other advice on this build?
Find a mountain Kenworth for sale, take out out the 12 cylinder diesel,(about 550 HP) and drop it in. You may want to add a blower to the diesel. That will fake out guys that hang around dark streets with their tricked-out Hondas.
850+ HP? The entire drivetrain, from engine to axle will need to be replaced with beefier stuff. That type of horsepower requires forced induction, so a lot of cubic inches with low compression will make it easier to reach. I like the 460 idea. They can be built up plenty stout for this project.
A custom two piece driveshaft can hold that power, but will require a beefier center bearing and reinforced frame mounting. A four link or ladder bar system will be required to keep the rear end planted. The factory leaf springs will buckle and twist like no-one’s business with this amount of power. Frame and suspension should be more than strong enough, being an F-350. This was designed for over-sized loads, so that should be OK.
Definitely need to go with a clutch and gearbox set-up that is strong enough for 850+ HP. I’m not sure the (guessing here) original three speed mixer can handle the extreme power you want. Most weren’t built with more than 400-HP in mind back in the 70’s.
The 850+ was a number to show serious business, not something that is a “WILL NOT TAKE LESS”. As I understand it, a 460 is pretty simple to build to 550 hp, and it has been suggested that I give it a 250 shot to get the numbers where I want them, scraching the need for a blower or turbo.
any bigger than 800 or so and I’ll save up and spit out 40 big ones and get the 800 inch 1800 hp bigblock I spotted on a ford racing site. Oh, the somedays… (that day will be a long time coming however)
the leaf springs on the rear are a good 3" thick, but they will still flap around? any idea where to look for, or how to build a set of ladder bars?
it’s running a granny 4sp right now (not sure if that makes any difference).
Would you suggest going to a built c-6, or keep a manual setup? (which is less $$$ to renforece).
I would assume that the huge 3" wide drums would deliver enough stopping power?
what axle would you suggest running?
thank you for your advice. in a week going over sites and asking questions, you are the first person to give actual facts.
A popular and affordable Ford stroker is a 460-based 514". It can be had in many different compression ratios, cam specs, heads, etc., to get it to perform the way you want. Those factory truck leaf springs are not going to be a very good choice for what you want to do. A coilover setup would work better, but if you still want to use the leafs, at least invest in a set of ladder bars and a housing floater, both readily available from any chassis parts supplier. A well built C6 can handle the power levels you’re contemplating, or you could use an adapter and run a pro-built GM T400, which is also available everywhere and is probably the cheapest tranny that can handle the power. As for gearing, with a big-inch, torquey engine and a good converter, you wouldn’t need to run a super steep gear. I’d suggest a 4:30 - 4.88 range with about a 28" tall tire, and top quality internals in the rear to handle the load.