I have a 91 f150 with the 302 5 speed and my 302 is on its way out so I'm going to start putting a motor together to replace it so I have not quite decided what to do build a 302 or build and swap in a 351w I have never rebuilt an engine before so this is going to be a learning exsperiance how much more work would it be to swap in a 351w over just rebuilding a 302 I would like about 350hp and about 400 ft lbs of torque at the flywheel I know a 351 could probably get that no problem but could the 302 whitch would be the easiest thanks

 

351W is drop in, and it will be much easier to meet your power targets.

You will have to convert to the Mustang mass-air computer though, in order to meet those power targets.

 

Whats all involved in a mustang mass air conversion what all do I need to do it

 

You'll need the mustang computer, the y-pipe intake from the 94-96 F-150 5.0 trucks, the air box, and the mustang mass-air flow sensor. There's a little bit of wiring involved, but it's not too bad.

 

I take it I'll need a 94-96 mustang computer and will my 302 headers work with a 351 and can I substitute a y pipe for straight pipes and I thought the 351 intakes were diffrent than the 302s

 

so i have been doing some parts searching online. And think i might go with a 408 stroker kit i found this one what do you guys think. https://www.summitracing.com/parts/sca-1-94306 The only thing i am worried about is the cast crank shaft. I have a forged 4340 scat crank shaft in my 700hp Camaro and i like it. But how is there cast crank shafts i don't want to spend the money on a forged one as i don't think ill need it for a dd truck with the HP and TQ i am shooting for. And don't plan on revving past 6000rpm. And what kind of heads and cam would you suggest for this set up thanks.

 

You need an 89 to 93 mustang computer. Keep in mind the more radical you get, the more extensive the tuning you will need. A stock Mustang computer with 24 lb injectors and a calibrated MAF could handle a 350 hp 351. A built 408 stroker is going to require a lot of tuning.

 

So a stock cubed 351 should be able to reach my goals with a head and cam setup if so that be the route I would take it would be cheaper and I don't want something that's going to be really complicated to get running its just a dd truck

 

350hp to the crank is easy with a 351. If you have the money, a stroker is a much better option and will easily reach your hp goals on speed density. I'd rather have a 408-427 with speed density and a 460 computer 24# injectors than a 351 and maf conversion....if money is a factor and I had to choose between the two.

In other words, money would be better spent on extra cubes vs tunability if you have to choose. Obviously tunability and extra cubes would be optimal if you can/are willing to go that route. You can also run a stroker on speed density (even factory 351 sd) and gather your money and time for a maf conversion down the road but it'll run great with speed density otherwise.

All you need for a low redline truck is a cast rotating assembly. Rpm is mainly what kills cranks.

As for heads, some ~190 afr's or similar aftermarket would be optimal. Your budget dictates what you get in the form of heads so telling us the budget would help in suggesting specifics.

 

Well I need to be careful with my money until I find out if I'll have a job at the end of the year so I was thinking around 4k do you think I could build a 408 with that if I do most of the work I'm likening the 460 computer swap over a maf conversion I'm guessing it's just plung in play with a 460 computer and is it still going to be as picky about the cam I choose

 

4k will get it done but you should probably not crack open a catalog and order some afr's. China aluminum heads (like pro comp) are probably better suited for your budget. You'll hear bad stuff about them but most people have no issues.

Gt40s is the cheapest upgrade over e7s but not nearly enough to take advantage of the engines potential. Ported gt40s would be a last resort, but if you're not porting them yourself you'll pay just as much as aftermarket heads for less performance.

Cam selection will be tricky because you will be able to run a cam that has more duration than the recommended 351 efi cam; the added displacement will tolerate more duration without sacrificing drivability. I'd be happy to recommend one for you but I'll have to sit down and look at some with comparison to the 351 sd friendly cam.

stock 351 intake is a prime example of how not to design an intake, it's a choke point of a 351 and would be huge choke point of a stroker. Budget for a replacement....typhoon intakes are cheap and lots of people run them with no complaints in functionality.

if you have 93 octane in your area and don't mind paying for it, plan your parts for 10.5-11:1 compression ratio. Substantial power gain and fuel econ increase.

460 computer and injectors will be a direct swap and it will run well and pull hard...it's what I've been running for years now.

As with any build, you should also include a wideband in your budget.

 

Yes I have 93 near me and I don't mind paying for it as long as I can get 10mpg I'll be fine whitch is what I was getting any way with a 302 that's not running good and what cam would recomind thanks

 

Comp makes an efi friendly cam: 35-351-8

218/224 duration @ .050, .512 lift, 114* lsa....this is the smallest cam I'd try running in a 408-427. I didn't do a ton of searching, so I don't know the specs of the off the shelf cams, but this is prob one of the largest duration cams you'll find with the efi friendly label. I think 220-222 on the intake side would be ideal for your setup and not risk idle vacuum woes, with exhaust around 225.

If you go custom, you can have them grind the duration I stated above with a ~.550 lift on 1.6 rockers and should be good to go.

I got 9-10 with my 302 as well, but I get 13-14 now driving how I want to drive. Increasing stroke increases thermal efficiency at lower rpm, and increased compression increases it across the board. Id expect a similar increase even with a 408 under normal driving. Thank you thermal efficiency.

 

Thanks for all the help I actually came by your thread on 460 computer and injector swap while searching for more info. It was a good read I leard quite a bit from it. So from what I gatherd from it souds like the more air I can move the happier the 460 computer will be. And since I'm going with a 408 over a 351 and afftermarket heads over gt40 heads. I suspect my set up could possibly run better would I be correct in this assumption.

 

You would be correct. Mine runs numerically rich at idle, but not enough to smell rich or destroy my oil. All other loads and rpm it's just fine, yours will be much better at idle but the computer does all the trimming/enriching it needs to do so long as you have an o2 that is functioning and it can go into closed loop.