Tom Wilson
June 1, 2013

SOHC 5.4 Into New Edge

Here’s a swap that requires almost nothing from the aftermarket, so there is no kit or shop championing it. Instead, this is a way of adding torque to a ’99-’04 Mustang GT using a wrecking-yard Two-Valve 5.4-liter from an F- or E-Series truck or van or Expedition. Key to this swap is keeping the cost of the 5.4 engine low, as a Three-Valve is likely a better choice because it fits better, is more sporting, and has greater hot-rod potential.

The Two-Valve 4.6 and 5.4 engines are similar enough that the biggest issue is likely hood clearance from the taller and wider 5.4. Items needing attention are to swap the Mustang oil filter/lower radiator hose mount onto the truck 5.4’s block if the truck engine has a remote-mount oil filter. It’s a simple bolt-on swap using stock O-ring gaskets.

The 5.4 oil pan should be replaced by the Mustang’s 4.6 pan to clear the chassis. It may be necessary to bend down one oil control baffle in the pan to clear one of the 5.4’s rod bolts, but otherwise the pan is a bolt-on swap. The dipstick tube will need minor bending and a new hole drilled in its mounting tab to clear the Mustang exhaust manifolds. The H-pipe will also require significant modification to reach up to the manifolds, which will be higher in the chassis.

It takes a practiced Mustanger’s eye to spot the taller 5.4 in a ’99-’04 Mustang GT. The idea is to add displacement for an immediate boost in power up to 4,250 rpm, and to better support tuning or other power initiatives (bolt-ons, nitrous). If you’re wanting a drive-around Mustang with easy grunt, and have ready access to a donor 5.4 and a worn 4.6 under the hood then this swap makes sense.

Flywheels and flexplates are mainly interchangeable (they are not balanced to the crankshaft) as long as you have the eight-bolt pattern (all 5.4s are eight-bolt cranks). Automatic applications must use the 4.6 flexplate as it has a closer torque converter bolt pattern.

Then there is hood clearance. You’ll want to run the Mustang intake manifold to position the throttle body, throttle cable, and so on, and that means fitting intake adapter plates (Professional Products is one source of these) between the 5.4 heads and 4.6 intake. This, and the taller 5.4 engine mean the throttle body ends around 21⁄2 inches taller than stock, necessitating removal of some of the stock hood bracing, or a taller aftermarket hood.

Because you’re swapping in a truck engine with torque cams, don’t expect the 5.4 to be a screamer. It’ll definitely heave harder below 4,250 rpm, but in stock tune it will fall off compared to the 4.6 after that. Tuning and hot rodding the 5.4 has definite potential, but you’d likely do as well for less money/hassle with a freshened and hopped up 4.6, too. Keep it cheap and daily driver easy and this one can be fun.

351W & Clevor Into Fox

Slipping a 351 in the place where a 302 resided is the classic Ford performance engine swap. It offers the big-bicep torque hit that’s fun to drive on the street, and these days 351s can be built big with way over 400 cubic inches if too much is just right. We don’t have the room to detail installing a 351 pushrod in a Fox or SN-95, but that’s OK because this time-tested exchange is one of the best documented, best-supported engine swaps going. It’s an easy to moderate swap depending how crazy you get with the 351 and how many of the 5.0 parts you’re trying to pinch pennies with; 20 years on in the Fox’s life we’re assuming you’re contemplating new everything from engine mounts to a fully dressed 351. So let’s examine the personality of this swap and hit the mechanical highlights as an introduction.

Addressing the 351W, this swap offers cubic inches for either satisfying street torque or big power at the track. It’s also a more durable engine, physically stronger than the 302/5.0 pushrod mill and a less-expensive swap than a Coyote (probably).

Of course, the main Windsor advantage, and the real reason to perform this swap, is to gain displacement. The 351 offers the most cubic inches possible in the light Fox and SN-95, short of the old 460 big-block. The 460 swap had its moment 25 years ago, but it’s too big and heavy to work even at the dragstrip. Besides, a 427ci 351W fitted with a blow-through centrifugal supercharger and carburetor will zoom past 1,100 hp, and we can’t help you if you think you need more than that. Back in the real world, naturally aspirated 392 or 408 Windsors are tough customers and a blast to drive.

Hedman’s (www.hedman.com) Clevor swap headers feature a flat collector. It allows better ground clearance while using large 17⁄8-inch-diameter primary pipes and doesn’t seem to affect performance much. Expect about a $600 price tag.

Highlights of this swap are the need for a rear-sump oil pan and pickup, 351 swap headers, and a taller hood. We also highly recommend the Maximum Motorsports swap-specific K-member to offset the 351’s weight, give header and starter clearance, and improve the handling.

This is just the beginning of the parts list, as the taller and wider 351 cannot use the 5.0 HO’s intake manifold, fuel rails, A/C and power-steering brackets, distributor, and so on. But assuming you have a dressed 351, the engine mounts fit the Fox/SN-95 chassis and the oil pan, K-member, headers, and hood are the main players. For more details and one of the best explanations of this swap, see www.mustang50magazine.com/techarticles/18818_351w_engine_swap/.

Everything about the 351W swap is applicable to the Clevor (or 351C) swap, except until recently the headers and intake manifold were issues. Now Hedman offers a swap header for 351 2V Clevelands in a ’79-’93 Fox (works with 351W, too), and Trick Flow has an R-Series lower intake for fuel injected Clevors.

Hanging a PS pump on aftermarket Cleveland heads is an issue, and manual steering is the usual solution. Use an all-steel lower steering shaft from Maximum Motorsport. Alternately UPR Products offers an entire front-end kit (K-member, control arms, steering rack and so on) for the Clevor Fox swap.

This is not the least expensive swap—the 351W would cost a little less—but it offers superb high rpm performance for a track car. There’s a bit more information on the Clevor Fox swap at www.mustang50magazine.com/techarticles/m5lp_1206_engine_swap_guide_heavy_rotation/.