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Swapping a Small Block into an SN95 Mustang


Want an old school small block in an SN95 Mustang? Ford offered the 5.0 in this body style for two years, which makes fitting a 302 or a 351 Windsor fairly easy regardless of model year. Fitting a Mod V8 or V6-equipped Mustang with one of these engines is mostly a matter of getting the right parts for the job.

Why Use a Small Block in Place of a Mod Motor?

While Ford used the 5.0 in the first two years of production, 4.6l SN95s are more common. Since the engine bay was already designed for a small block, doing an engine swap is straightforward. The same goes for V6-equipped Mustangs, which are available at bargain prices.

If you’re looking for serious power, even on a budget, a 351 Windsor is a good place to start. Stock blocks are a lot stronger than the 5.0’s, and they can be bored and stroked to get major increases in displacement. In many cases, using one of these engines will be an easier path to big power than sticking with a Mod motor.

Swapping a Small Block into a 4.6 Liter SN95

The engine wiring harness, fan controller and mass air sensor will need to be replaced, as well as the K-member.

When fitting the engine to a transmission, keep in mind that the bellhousing is longer than the Fox body. Automatic transmissions integrate the bellhousing into the transmission case, so there’s no direct route to mate it to the engine.

Swapping a Small Block into a V6

The K-member for 94-95 V6 Mustangs is the same as the one used in the 5.0 SN95, but new motor mounts will be needed to fit a V8. Likewise, 94 and 95 radiators are the same with different versions for manual and automatic cars. The transmissions are even identical down to the bellhousing’s bolt pattern. The engine wiring harness, fan controller and mass air sensor will need to be replaced, while the V6’s 7.5 rear end should be replaced with a stronger 8.8 to handle the added power.

Dropping a 351W into an SN95

Getting a 351 Windsor into an SN95 is a little easier than dropping one into a Fox body because the engine bay is designed for the wide Mod motor and Ford used the 351 themselves in the Cobra R. Depending on your donor engine, a 351 will be 35-50 lbs. heavier than a 5.0.

Since they’re both based around the Windsor design, the 351 will fit on a K-member designed for the 5.0. Swap headers need to be used to get the exhaust to clear the frame, and the 351’s front sump oil pan and pickup need to be replaced with rear sump versions to match the shape of the 5.0’s oil pan.

The 351 uses a different crankshaft imbalance than the 5.0, requires a compatible harmonic balancer and flywheel. A spacer is also needed for the balancer to line up the serpentine belt with the stock accessories, as well as some different mounting brackets to bolt everything up. With the right parts, the motor can be used with the original power steering pump, air conditioner and alternator.

The 351 is three inches taller than the 5.0, requiring a taller hood or shorter engine mounts to fit the engine bay. If you’re using a junkyard engine, the stock truck intake manifold will be far too tall; switching to a car upper manifold or a complete aftermarket intake will solve this problem. The valley is wider on this engine, so the stock 5.0 lower manifold won’t fit. A shorter alternator will also reduce total height: one from an EFI 351W truck will work, but the cast iron gear needs to be replaced with a steel one when used with a later roller cam engine.

Performance heads for the 5.0 will work with the 351 as long as they’re designed to fit the 351’s larger studs.

What Should I Upgrade?

Junkyard motors are a good budget option, but it can be a lot easier to start with a new crate motor. Ford Racing offers options ranging from the affordable 302 Boss to the crazy Z460, a 460-cubic inch Windsor that produces 575 hp.

Even if you don’t need to replace the K-member, an aftermarket unit will be much lighter and stronger than what was fitted at the factory.

The stock cooling system and fuel system are adequate for a stock 5.0 or 351, but it won’t take much to run into fuel and overheating problems. If you don’t need air conditioning, getting the lines, condenser and other hardware out of the car will be easier with the engine out; we have adapters for both motors to delete the compressor pulley. The stock alternator is also weak by modern standards.

No matter which engine you choose, modifying it before dropping it in the engine bay will make the work a lot easier. Anderson Ford Motorsport has helped owners get the most from their Mustangs long before the SN95 was in production, so we have the Ford Mustang performance parts and expertise to help you get the most out of your engine swap.

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