Ford Engines - 302 to 351

January 15, 2015, 12:56:47 PM

Found a tid-bit of information that explains Ford Motors in the 302 to 351 range pretty thoroughly. I thought posting it to help anyone that was deciding on an engine swop in the future or engine modification. Sorry Turbo Coupe and V6 owners-nothing personal. :D

260, 289, 302
Small blocks in the Windsor family, just smaller and weaker than the 351W.

Windsor’s are the smallest of the V-8 engines, with the 289 and 302 being the most common. The problem with those is that it is hard to get any “real” power out of them (torque) because there simply isn't enough stroke, and the stock heads have tiny little runners and valves. You could cover the entire exhaust port between the tip and first knuckle of your thumb! When you do build them to make serious power, (aftermarket heads, blown, nitrous, etc.) the blocks just don’t take it very well because they just aren't beefy enough.

In 1969 Ford came-out with the 351 Windsor which was basically a beefier version of the 289 / 302, which are about an inch taller and wider than a 289 / 302. Side by side (a 289/302 next to a 351W), it is hard to see the difference in size, but the Windsor has larger head bolts, larger – thicker main caps, larger & stronger main bolts, thicker main webs, a taller deck height for much better rod angles and internal geometry, etc, but sitting side by side to a 302 it looks almost identical. They pretty much all use the same timing covers, water pumps, valve covers, exhaust manifolds, etc. between the 289, 302 and 351W. It is more “internal” differences than external, but the power making capabilities and power HANDLING is MUCH better. The only "bad" 351W's to use are the 69 and 70 blocks because they had a shorter deck height of 9.480". In 71 Ford decided to raise the deck to 9.503". It's only a .023" difference. It doesn't sound like much until you go to find pistons that don't stick up above the deck surface, so we prefer to stay away from 69 and 70 blocks and just go with the 71 and up blocks.

In the 80’s when the 5.0 Mustangs were getting more and more popular, companies like Edelbrock, Trick Flow, and other’s began making much better designed heads with larger valves, larger runners, better designed combustion chambers, etc that could support making MUCH more power than any factory 289/302 ever could. Once companies like Air Flow Research came into play with CNC’d heads that make amazing power numbers, and companies like Paxton, Vortech, etc stared the centrifugal supercharger craze, the game was on, but the problem was, the 289/302’s just didn’t have the cubic inches to make any "real" low-end torque, which is much more important than “horsepower” for moving and accelerating a vehicle, nor the strength to contain and handle all of that added power, so the 351 Windsor’s began coming into play. With a 351W you could have a MUCH stronger engine and make MUCH more power (and torque) than ANY 289/302 based engine. Once this took hold, companies like Scat and Eagle began making better & stronger cranks, rods, etc and began making stroker kits to turn little 289’s & 302’s into 331’s and 347’s! They also began making stroker kits for 351W’s to make 393’s, 408’s and 427’s out of them! Now you could build a fairly tame small block that can easily make 450 HP and 500 Ft. Lbs. of torque on plain old pump gas in a package that can easily fit under the hood of a 65 Mustang! More commonly building 408’s that make upwards of 530 HP and 575 Ft Lbs. of torque (on standard pump gas) that with good traction and a decent stall converter commonly propel 65 / 66 Mustang’s into the low 11 second, and even the mid 10 second quarter miles times in basically full street trim! Not even new Shelby GT500’s with their supercharged 5.4L / 540 HP engines cut those kinds of quarter mile times.
Of course there’s a LOT more to it all than what I just listed, but for the “basics” of what the differences of these Ford engines are, this gives you a pretty good overall idea.

351C
Basically all Cleveland type engines (canted valves), classified as mid sized blocks. Not really a big block, but not a “small” block either. Cleveland’s are based off the famous BOSS 302 from 1969 and 1970. The BOSS 302 was short lived because Ford figured out that the massive valve and head runner sizes worked pretty well in Trans Am racing, but not very well on the street unless you were at 6,000 – 8,000 RPM and had really short rear-end gears. 302 cubic inches simply wasn’t enough cubic inches to achieve any velocity through the heads to make any torque or low to mid range power on the street, which is why it only lived 2 years in production. In fact, Ford made the valves smaller in '70 BOSS 302 heads than they were in the 69 BOSS heads to help remedy the sluggish, low velocity issue, but it still didn't help much. Ford decided to make the 351C-4V which is very similar to a BOSS 302 except with 351 cubes to make those heads work a bit better. They even had a BOSS version with 4 bolt mains. You usually saw those in Panteras and rare Mustangs like the Ram Air Mach 1's, etc. Ford also modified the combustion chambers with a dual quench design to help get a better burn in the cylinder and made the valve sizes a smidge smaller than what the 69 BOSS 302 came with to help with lower to mid range RPM flow and torque. Ford also got wise and made a 2V version with MUCH smaller runners in the heads, much smaller valves, etc which ran fairly decently on the street and made much more low- end torque and response than the 4V version. It was a better suited engine for larger / heavier cars and for "normal" driving. The problem with Cleveland’s though is that compared to a Windsor, they are heavier, much bulkier and make for exhaust header issues when swapping them into cars like Mustangs, etc. Not to mention the head runners are just too large for most guys on the street unless you have short rear-end gears and high stall converters. A great variation to remedy a lot of the issues is to turn one into a 393 stroker, The added cubic inches makes the heads work better and adds to making more low-end torque. It’s quite easy to get 500 HP and around that in torque with a well built 393 stroker.

The problem with Cleveland engines, other than what I just listed above, is that they are more expensive to build than a typical Windsor engine, not to mention they are heavier and are much bulkier in an engine bay than a Windsor, so in a lot of cases, guys with cars they are modifying for performance use tend to set their Cleveland's aside and swap over to a Windsor engine. Headers fit better, they're lighter, less expensive to build, they have better designed heads, etc. In fact, even guys with Panteras do this Windsor swap to lighten-up the car and make it more responsive at lower RPMs. Ford dumped the Cleveland engines for a reason... and they stayed with the Windsor platform for almost 4 decades for good reason. If you have an original Cleveland car that you want to keep stock, like an original 351C-4V Ram Air Mach 1, etc, then by all means, it DOES make sense to stay with the original Cleveland, but if you want to build something for performance use that has more options and less costly components, then I'd suggest going with a Windsor.

Ford also had the 351/400M (M stands for “Modified”) which appeared to be identical looking to a 351C except they had a taller deck height and the bellhousing bolt pattern is the same as the big blocks, so it's different than the small blocks and the Cleveland's. You found these engines mostly in late 70’s trucks and large / heavy cars. They were only like a 4 or so year production. The fact of the matter is; the Cleveland & Modified type combustion chamber is just a “dirty burning” design so Ford dumped the engine family because of smog issues and continued on with their Windsor’s in 5.0L and 5.8L (302 and 351).

351W
The W stands for Windsor. A small block that is about 1” wider and 1” taller than its little brothers, the 260, 289 and 302. More info on these engines below in the 289 / 302 area.