Eight from Four: Fox Mustang 2.3L to 5.0L Swap Guide

Power-steering pumps on four-cylinders feature a unique switch thatshuts off the air conditioning to retrieve horsepower for poweremergencies. Although the pumps are changed from the four-cylinder tothe V-8 because they have different mounts, the hose itself from thefour-cylinder usually stays in the engine bay. That's because removingit requires loosening the rack-and-pinion to unbolt the hose. Since thehoses are the same, you can avoid this extra work by using thefour-cylinder hose and then simply removing the switch and blocking thehole with pipe plug.

Or, you can change the four-cylinder hose to a V-8 power-steering pumphose. Here's a hose from one of Bill's salvage 5.0 Mustangs.

A four-cylinder radiator is a two-core, the same as for any otherengine. The four-cylinder, however, uses a different shroud and anelectric fan, while the V-8 uses a flex fan.

The five-speed clutch cable for a V-8 (top) and a four-cylinder (bottom)are the same length. The ends, where the cable hooks to the throw-outbearing fork, are different. If you use the four-cylinder cable on aV-8, the clutch will be so tight it will burn up. Bill d'Happart hasseen this first-hand when customers come to his shop with worn-outclutches--and he discovers they had a four-cylinder cable. It wouldn'trelease the clutch enough.

You must swap the four-cylinder's five-speed for one from a V-8. Thefour- cylinder five-speed (bottom) has a lower First gear, but that'snot the problem. The gears and teeth in the four-cylinder's five-speedare smaller, and in general parts inside are downsized. The V-8five-speed is stronger. Five-speeds for V-8s generally cost from $400 to$500 used. Note: A V-8 also requires a V-8 automatic, either an AOD or aC4. The four-cylinder automatic will not fit a V-8. Shifters are thesame between these transmissions.

Notice the input shaft on the V-8 (left) is bigger in diameter. Forddoesn't even stock a pilot bearing to mate a four-cylinder input shaftto a V-8. Some backyard builders have installed four-cylinderfive-speeds behind V-8s, resulting in the shaft wiggling back and forthuntil it wears out the bearings in the transmission.

Driveshafts are interchangeable from one engine to the next, with theexception of the four-cylinder automatic that features smaller splines.To use it for a V-8 application, change to the bigger yoke. Thefour-cylinder driveshafts have an extra plate on the front, molded onwith rubber, for vibration damping.

The tach pointer on a four-cylinder will jump to an incorrect rpm aftera V-8 swap. So you have to pull the face and install a V-8 tach for acorrect reading.

The fuel lines, although the same diameter, must be completely changedbecause the connections are different. This photo of a four-cylinderfuel line (left) and a V-8 fuel line (right) show the dramaticdifferences. Gasoline tanks are identical, as are the fuel pumps insidethe tanks.

The lower-rate four-cylinder springs will work on a V-8. Just leavingthem in place is an inexpensive way to lower the car. For the bestperformance, stock V-8 springs or an aftermarket set are the bestchoice.

The four-cylinder disc brake rotors are smaller than the V-8 rotors. Formore stopping power, it's best to get the larger V-8 rotors andcalipers, which require the V-8 spindles as well.

The front sway bar is noticeably larger on a V-8. Changing the stockfour-cylinder sway bar depends on the application. For drag racing, thesmaller bar actually provides better weight transfer to the back of thecar, which is good for straight-line performance. Bill says thefour-cylinder bars work fine for everyday street use. The builder whoplans to autocross should certainly upgrade his front bar.

The first year of the 8.8 was 1986. The 8.8-inch rearend is an integralpart of any V-8 performance swap.

The brake lines on a four-cylinder are on the passenger side. The V-8brake lines are on the driver side. If you leave the four-cylinder brakelines in your swap, the right-side exhaust is up against the hose forthe brake lines, which is dangerous. That's why it's mandatory toconvert to V-8 brake lines.

The 8.8 axle comes with quad shocks, which mount to this bracket that isbolted to the frame. Four-cylinder cars will not have this bracket.Sometime during or after 1984, when quad shocks debuted, Ford begandrilling all frames, no matter the engine, for this bracket. Billadvises welding this bracket to frames that do not have the factoryholes punched.

Four-cylinders did not come with rear sway bars. It's a good idea to addone for more stability in the corners.

True dual exhaust with an H-pipe requires a double-hump crossmember. Itcan be sourced from the '79-'93 Mustangs listed in the table on the first page of this story.