I am planning to rebuild the stock 302 in my 89 ford F-250 4x4. I am very new to engine rebuilding and realize that lack of proper planning will result in me spending way more than I should and wishing I'd done something different to begin with. To start with I am wishing to drive the truck regularly, pull moderate loads, make the pipes talk to me occasionally and would like to feel it rumble a little. I would like to know that the motor is stought, which in its current state, it is most definately not for the size of truck. I love the sound of tuned up engine but don't need to go extremely wild and must operate within a reasonable budget. I have been considering a 331 or 347 stroker and from what I have read sounds like the 331 is probably a better fit for my needs but I am not certain about this. I have also thought about changing the rear end gearing, which is believe are 3:55's. I would appreciate so very much is someone would suggest the parts I need to acheive my objective and supply me with the vendors who would have the parts and to suggest a compatible rear end gear to give me some more torque/pulling power. Would also like to know if it is possible to get a bull dog gear in the stock 5 speed transmission or if changing the gears would accomplish this? Last question is how does changing the rear end gears affect the transfer case gearing and 4 wheel drive gearing? Sorry for so many questions, just really need some detailed help to get me going on this and confident I'm going in the right direction? Would like to have completed by spring of this year? Thanks very much for your replys.

 

If you have the mazda 5 speed, then the easiest answer to that is, swap a ZF tranny in place of it, its a bolt in deal and theoretically, much stronger than the mazda, also has a lower first gear.

Keep the gearing compatible with your tire size and expectations...more gear would be better but if you plan on adding even taller/bigger tires, then you'll need to take that into consideration.

If your starting from scratch why not find a 351w and stroke it or purchase a crate engine.

If you would want to keep the 302, why not go 347? You can add larger heads later and the extra ci will give you a couple more ftlbstq to play with now...besides the 302/351w used the same heads from the factory...cubic inches are cubic inches right?

Do a search, a fella just finished installing a 331 in his truck and he seemed to be very happy.

Good luck

 

A 331 will definitely give you that extra power you're looking for, but the motor will need to be equipped to support it. This means let your machine shop work your factory heads to support greater airflow, otherwise the extra displacement will hardly be able to pump more air. A much better alternative would be a pair of aftermarket heads, like Edelbrock's Performer RPM, would be ideal for a 331 or 347. A 331 with aftermarket heads will be a real beastmonster, but you'll definitely want to do headers with it, and at least get a chip that understands your FI needs. You'd also want to do a cam, because it would be a waste of potential to have a motor ready to rumble like that but not have a cam that could make use of it. In my opinion, a stroker motor is a waste of money unless you can support greater airflow through the heads, intake, and exhaust. You could just keep your 302 and do a .030" overbore to clean up the block, and have a 306 that you could do the same mods to I listed above. You can make awesome power numbers, and have a reliable, efficient ride with a 306 equipped with a bunch of aftermarket goodies.

The 331 vs. 347 debate always incites much passion, but there's one thing that nobody can dispute: nobody owns a 347 with more than 50,000 miles on it that doesn't have awful piston slap and excessive oil consumption. I know the newer kits have revised oil control ability, but 3.4" is too much stroke for the 8.6" deck Windsor block. The 331 uses a 3.25", which is much, much friendlier to long term use. I don't see any reason why a 331 couldn't live for 150,000mi. or more.

Of course all this theory here has probably blasted your budget, but there's another option: If you're really a power-hungry gearhead, then yank a 351W from the boneyard and put one of those 3.85" stroker cranks in it with a .030" overbore. Is 393 enough displacement for you? This would cost almost exactly the same to build as your 302 would to have it rebuilt (minus the new oil pan, installation accessories, distributor, etc.), except that you'd have a heck of a lot more power. The 393 would definitely need some major head work, or aftermarket heads (preferable) to have any chance at reaching its potential. Are you looking at doing a major motor investment, or just some ideas to spruce up your 302? Is off-roading part of the equation?

 

I often hear the 347 is not very reliable but when you look at who is buying the 347 kits/engines, you can't really expect a long service life.

On paper the rod ratio for the 331 is better when compared to the 347, so I suppose it would be reasonable to expect a slightly longer life but how much would be the question, there is a difference in the rod ratio..1.5 for the 347 and 1.6 for the 331....however the 351w looks real good at 1.7. Who knows? later

 

It's all about geometry. I know the stroke/rod ratio is close on both of them, but even an 8% increase in S/R might make the motor last twice as long. The 347 turns too high of an angle in rod sweep about the wrist pin, thereby inducing differential stresses on the piston walls, eventually creating piston slap. The rotating mass has too much inertia when stroked that far, and it overstresses the smaller mains. The 351W has beefier, Cleveland-style mains that are much better suited to handle more rotating mass. Some say that it's just talk, and 347's are great motors, but my final word is that I have challenged people all over to show me a single 347 that remains healthy after 50,000 miles of street use. I think we can hear the crickets chirping....

 

Your right, it might, it would be interesting to see some sort of test done.

 

I'd love to see a test done. You always hear about the buildups in the magazines, but you never hear from them years or even months later. I personally know of Mustang idiots (18-26 year old males, usually the parents buy the vehicle) with the money spending discipline of an 11-year-old who keep throwing 347's in theirs, and wonder why they have to replace them every 25-35,000 miles. Some have wasted totally functioning factory motors in favor of these swaps, and are consequently on their 3rd motor. That's no big deal if you're driving a '68 F-100, but when you own a 2000 Mustang GT, it's getting out of hand. Some mod-motors blow up just as quickly on their own, with no internal mods. "I'm using a different machine shop this time, that last guy didn't know what he was doing". If you want to be one of these guys, please buy a Honda, so that you don't send a Ford to an early grave!

 

You lost me right about here....?..

 

Another thought...a 393 has the same rod ratio as a 347...how many complaints do you hear about those? None, IMO for one reason, no one builds them for dependablity and when they do break, given the target market (drag racers), its accepted, as anything pushed to its limits can break. However when they are in mild applications they seem to be very reliable, yet its not an issue because its usually in an underpowered street vehicle. So maybe its not so much the 347 is unreliable but its pushed beyond its capability, as usually those running 347's are also competing again larger 351w variations or BB's. So in higher hp applications the 331 maybe ideal due to its slightly improved rod ratio, as far as longevity but that doesn't mean a 347, in the right build and proper application, wouldn't be as dependable, right, when use correctly? Who knows? This is an interesting topic. Later

 

Instead of buying new heads. Take your existing ones to a machine shop and have them port matched to your plenum and exhaust. Dont forget to take your gaskets as well. What this does is match the port holes of the heads to the same size as the intake and exhaust (actually the gasket). For some reason Ford was really off on those calculations, at least on my 302. Dont tell the machine shop this, but there is a lot of metal to be grinded off of that head! Make sure they smooth out the surface and give it a valve job while your at it. I had mine done for under $400 about 4 years ago. WELL worth it!

 

The 2000 Mustang comment was about people who do retarded mods to the new modular V8's, like put superchargers with way too much boost, or just revv them too high, or just do stupid things in general. I've never seen anyone swap a 347 into anything after 1995.

It's not just about stroke/rod ratio with regards to the 393. It's the fact that the oil control ring intersects the wrist pin on most 347's. The 393 holds together better because it has larger mains to anchor the rotating mass. Yes, the mains aren't titanically larger, but it's all about inertia, and even a slight increase in diameter of the mains gives a much greater surface area to bear the load across the face of the bearing. I think that even if 347's were properly cared for, they'd still end up falling to pieces too soon, but you're correct that people don't build 347's to properly care for them.

 

Why is everyone so quick to build a stroker? I'll tell you. Because it can compensate for a poor combination of parts and general lack of knowledge. Ford has been using rod ratios around 1.7 all these years for a reason. It's the best compromise between power and longevity. I'm not disputing that more stroke makes more torque. But a stroker should be the last resort, not the first. Start with some of the AMAZING aluminum heads available today. Take advantage of the compression and timing afforded by the heads and build a combination based on the power curve that suites the application. It's actually that simple. Oh hell, what am I saying? Go ahead, build yourself one of those piston slappin', oil burnin', shakin', short life motors. Oh yeah, might as well have 12.5 to 1 compression to go with all that stroke. It's only time and money. Best of luck.....

 

dude, once we get that big 'ol stroker put together, we can slap a 14-71 blower and about a 1,000 HP shot of nitrous. That should put us into the 8's, especially with the stock drivetrain. We can use all of the prize money from the local drags to buy some stickers & bass equipment. That'll get us on the cover of any magazine!

 

Well one reason why the mod motor fans are quick to throw a blower on their car is because crazy amounts of hp and tq can be made, as compared to a stock ford pushrod engine. Worth the risk? Well not if longevity is your goal but to attain a goal in short order...sure. Whether one application is better than another is a difficult one to judge, everything has its place, build it accordingly and you'll be fine. Besides once you've done the first mod you've reengineered the engine right?

 

I just think it's funny how many of these kids that go to car shows and drags have a new car that their parents bought them, and they void the warranty with superchargers, and then try to push it even further, sometimes with catastrophic consequences. It's just unwise.

Building your 302 up with warmed-over factory heads, or high-quality aftermarket heads and a well-matched cam is a good idea. You'll have a durable, efficient motor that will be reliable to drive anywhere and a heck of a lot of fun to throw some mud around in. Throwing an aftermarket supercharger on your '03 Mustang is a very bad idea, see above.