Howdy all, Figured I'd go ahead post my new project truck. I've just got a hold of a 1982 4x4 F250.. I haven't even looked at it yet but is supposed to be a pretty squared away truck.. good axles, C6, needs a motor ( had a 460) not bad for 150$$ if ya ask me.. I'll probably put a "welfare" 351m in it for now until I can figure out what else to put in it. I'm thinking a small block with the price of gas these days, Maybe even a 300 I6. I've had a 77 f100 302/c4 never did run perfect but I drove the crap out of that truck and still couldn't kill it. Always been a ford truck fan especially 4x4's.. anywho found this site doing some 'googling' and here I am. lots of good info.. expect the questions to start pouring in when i get the beast home.. later..

 

May as well put a 400 in it, if you're willing to look at an M block. The 400 has a longer stroke than the 351, and lighter pistons. It will get the better mileage of the two, and is the more worthy of the two to build up for power. Even in stock(welfare form) it's a torque monger(long stroke!) and there's a lot of hidden, un-tapped power in that engine with a decent rebuild, adding some mild compression and cam upgrades.

The M blocks should bolt in with some mild changes, as opposed to changing over to a small block that is barely capable of hauling around a 3/4 ton truck. Small engines were offered in them, and did the job, but you're looking at a heavier truck, so the smaller engine will have to work harder than the bigger engine, in the long run.

I would race to find another 460, the 400 would make you as happy, with a decent rebuild. Keep the mods mild(stockers came with 7 or 8:1 compression, so bumping to 9 or 9.5:1 would be more than enough of a compression boost for street use, along with a mild dual pattern RV cam(260/270 comp cams dual pattern rv cam's work extremely well from my past experience with several different Ford engines), add a small 4 barrel carb(around 600-650 cfm, no more, with vacuum operated secondaries) from Edelbrock, and one of their infamous torker series intakes, and you'll have an engine that will respond, as well as get respectable mileage for a truck. Driving it for mileage, is up to you.

 

I can get 2 351m's for probably a couple hundred bucks.. Ones locked up and the other needs a set of heads.. I was thinking of doing a 400, get a good crank, rods, bearings, and pistons.. That way I'd have a clean bottom end for about the same price as a rebuild.. A 460 is not out of the question, I'd just have to find one for the right price.. Also, what's the deal with the 351m? I've always heard emissions is what killed the power, retarded cam etc.. Never seen first hand, seamed to perform all right to me... Oh, and if the trucks capable of double digit gas mileage.. It's fine by me..

 

The 351M is a destroked 400. It also has heavier, low compression pistons.

That being said, both engines have a surprising amount of hidden power in them, with the addition of mild performance parts.

If I were to build either, my choice would be 9:1 compression pistons, at least .030 over moly faced rings. Machine the crank and put under-sized bearings in. New cam bearings, 260/270 dual pattern Comp Cams rv cam. Definitely have the heads looked at, and replace any worn guides/valves, seals. A mildly heavier than stock set of valve springs will actually reduce valve float at higher rpm, and improve power and mileage.

One of the issues with the M series engines was oil flow, and some performance shops will do a flow job on your oil journals, as well as drain back holes, to alleviate this..IMO, worth the money. I'd also add a high volume oil pump, new push rods and lifters, and a small(say around 600cfm) Edelbrock street performance carb, and torker series intake.

That combination will work really well for a daily driver, and still let out a howl from the rear tires if you're in the mood to wake up the neighbors.