Jeff Smith Senior Technical Editor
April 1, 1999

It takes dedication to be a hot rodder. You have to be part engineer, part physicist, and part mechanical genius. If you happen to be a Ford fan, you must learn to avoid the common pitfalls that are a no-charge part of the Blue Oval world. It must be that Ford engineers take deranged pleasure from making parts that almost interchange. While hot rodding will always be a game of mixing and matching parts, it seems especially tough for Ford fans.

It’s often helpful for a Ford fan to know what not to do so he can either fix or avoid problems altogether. To help you out, we’ve talked to a few knowledgeable Ford sources, such as John Vermeersch at Total Performance (who also runs the Motorsports Technical Hotline), Chris Kaufmann at Kaufmann Products, and Mark Sanchez at Advanced Engineering West. These experts have come up with some of the most common Ford mistakes and ways to avoid them. Commit these gems to memory and make fixing up those Fords a far more fun experience.

The distributor gear on the right illustrates what happens when you don't use the proper distributor gear with a steel roller cam. Imagine all those iron filings going straight into the oil!

Gear Up
The late-model, roller-cammed, fuel-injected 5.0L engine has become the powerplant of choice for a number of Ford followers. The popular plan is to buy a used, fuel-injected engine from a wrecked Mustang or T-Bird and fit it with a carb and a different distributor. What most folks don't realize is that the steel roller cam requires a special distributor gear. Since all 289/302 Windsor Ford distributors interchange, it's easy to drop in a distributor and fire up the engine. Unfortunately, the steel roller cam will quickly chew up a nonroller-cam distributor gear and will probably destroy the cam gear as well.

The quick fix is to add a bronze or specific steel-compatible distributor gear to the distributor. Crane Cams offers a high-quality silicone copper alloy gear that is superior to the inexpensive bronze gears. There are two different shaft diameters, 0.467 inch (PN 52989-1) and 0.500 inch (PN 52990-1), for the 289/302 Windsor distributors, and remember that even the silicone alloy gear will wear at a faster rate than normal.

The Ford SVO catalog lists three different gears that can be used with a 0.467-inch distributor shaft. Its newest is a steel gear compatible with the factory steel roller cam and aftermarket cams (PN M-12390-B), while a larger 0.531-inch-shaft-diameter steel gear for 302 EFI roller-cam motors and all 351W engines is also offered (PN M-12390-F). An SVO bronze gear (PN M-12390-E) is also available.

This flywheel and harmonic dampener are for the heavier 50-ounce external-balance, late-model 5.0L engine. Notice the size of the imbalance weight located on the flywheel and harmonic dampener. The lighter 28.2-ounce flywheel or dampener will have roughly half the size imbalance weights, making it easy to spot.

Balancing Act
Another problem that crops up when swapping later-model small-block Fords into earlier-model cars is flywheel or flexplate balance. Many Ford enthusiasts don't know that Ford changed the external balance weights of the Windsor small-block in 1980 with the introduction of the short-lived 255ci V8. The external balance changed from 28.2 ounces to 50 ounces with the '80 engines.

Other than this change, the flywheel/flexplates are the same, which means that they will interchange. While this change may not sound significant, if you bolt a pre-'80 flywheel or flexplate to an '80-or-later small-block (or vice versa), the engine will vibrate horribly from the moment you fire it up, causing severe engine damage if driven for even a short period of time. In some instances, the later-model flywheel or flexplate may not fit inside the earlier bellhousings, since Ford offered both 157-tooth and 164-tooth flexplates.

Not only is the firing order different on the 302- and 351W engines, but Ford also numbers its cylinders differently than GM engines.

All's in Order
Many neophyte Ford freaks don't realize that the firing order of the early 351W engine is different from the 221-, 260-, 289-, 302- and late 351W engines. The early 351W's firing order is 1-3-7-2-6-5-4-8, while the smaller Windsor engine's firing order is 1-5-4-2-6-3-7-8. What makes this interesting is that 289/302 cams are completely interchangeable with 351W cams, providing you match the firing order to the camshaft. If a 289/302 cam is used in a 351W engine, the firing order must be changed to the 302 sequence by moving the wires on the distributor cap. The same procedure is used if a 351W cam is used in a 289/302W engine where the firing order in the distributor cap must match the camshaft.

Unfortunately, this trick won't work with sequential EFI engines like the 5.0 if a 351W cam is installed, so be forewarned. According to Kaufmann, switching the plug wires will make the engine run, but power will be down dramatically. The fix is a new ECM to establish the correct injector firing order.

There's no easy visual way to tell a serpentine-belt-drive water pump from a V-belt water pump unless you remove the rear cover of the pump and look at the the pump impeller vanes. So make sure your pump is correct for the belt-drive-system application.

Reverse Cooling
Engine swapping late-model, serpentine-belt-accessory-drive-equipped engines into earlier cars can also lead to problems if the late-model engine is retrofitted with a standard V-belt pulley drive system. It's easy to overlook the fact that serpentine-belt drives rotate the water pump in the opposite direction from V-belt drive systems. If you equip a late-model 5.0L engine with V-belts without changing the water pump, water pump efficiency will drop radically, and the engine will overheat. The same is true if an early-model engine is equipped with a serpentine-belt drive. The simple fix is to equip the engine with the appropriate water pump for the accessory-belt drive you are using, regardless of engine year.

This is a late-model, four-bolt harmonic dampener for a 5.0L engine. Note the position of the TDC mark (1) compared to the crank keyway (2). Earlier three-bolt dampeners will have a different location for the TDC mark. Earlier three-bolt dampeners will have a lighter external balance, too.

Timing Mix 'N' Match
Hot rodders revel in the mix 'n' match form of building a car. Often, parts come from unknown or long-forgotten sources. One source of headaches is Ford's switch from three-bolt harmonic dampeners to four-bolt pulley-mount dampeners around 1968. While that can cause problems in itself, the real challenge comes when the timing marks don't line up. In addition to the pulley-bolt-pattern change, Ford also changed the location of the TDC mark from the left (driver's side) to the right side of the engine. If your timing mark is 90 degrees off, you can change pulleys, change the location of the timing mark indicator or use an aftermarket timing tape to indicate TDC referenced 90 degrees from the original mark.

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T5 Trans Trickery
The Borg-Warner T5 trans is the hot ticket for budget Ford street heroes, butthe proliferation of those transmissions can lead to problems. Before you step up to buy a used T5, be aware that not all T5s are the same. Later-model Mustang T5s, beginning with '90 Mustangs, are upgraded transmissions that offer much stronger nickel-steel gears and superior synchros and are highly prized by knowledgeable Ford fans. They can be identified by a B-W tag listing either a 1352-208 or 1352-199 serial number.

If you are junkyard or swap-meet hunting, keep in mind that the four-cylinder T5 transmission looks the same but actually has a longer input shaft and slightly smaller-diameter pilot shaft. If you bolt the four-cylinder T5 into a V-8 application, the clutch will chatter on engagement, because the pilot shaft is loose inside the pilot bushing. Worse yet, the longer input shaft presses forward into the crankshaft, placing pressure on the thrust surface of the main bearing, which will quickly destroy the bearing and cause major engine damage.

If that isn't enough, four-cylinder transmissions have deeper 4:1 First-gear ratios that are substantially weaker than the V-8 boxes. Borg-Warner engineer Steve Whitaker advises that you steer clear of pre-'85 V-8 T5s, as well, since they are a little weaker than the post-'85 models. Furthermore, the new '94 Mustang T5 is different from either of the previous T5s and will not interchange. Hey, nobody said it was easy! The bottom line is that there's no reason to buy a four-cylinder T5, even if it's dirt cheap.

The head on the left has the Ford-supplied insert (1) that also blocks off the exhaust port. The head on the right is open (2). You need to look carefully to ensure that the plugs are in place, or you'll have a noisy exhaust leak.

Leakproof
All Ford small-block heads since the 1975 are configured to accept smog-pump input into a hole in the back of the right cylinder head that is plumbed to the exhaust ports. The hole is drilled and tapped in both heads for a 5/8-inch national coarse (N.C.) thread. Ford inserts an adapter plug that is internally drilled and tapped for a 3/8-inch N.C. thread for the opposite end of the head in the front to mount the accessory-drive bracket. When an engine is rebuilt and bolted into an emissions-exempt vehicle, the rear hole may be left unplugged. Left open, the holes will generate a tremendous exhaust leak that may not be immediately apparent and could be blamed on leaky header gaskets. If the smog pump is not used, the O.E.M. Ford 5/8-inch blind hole insert (Ford PN 351418-S) is a simple and inexpensive fix to this problem.

Using a quality head gasket, such as Fel-Pro part No. 1011, line up the steam holes between the gasket, head and block. If you find the indicated passages (arrow) not drilled in either the head or the block, carefully drilling them could eliminate an overheating or detonation problem.

All Steamed Up
When mixing and matching Ford small-block cylinder heads and blocks, there is a great possibility of mismatching steam-pocket relief holes between the heads and the block. If the steam pockets are not vented properly, they can cause internal water-jacket hot spots that can lead to detonation and engine damage, especially in high-output, high-compression situations. The fix for this problem is to line up a head gasket such as a Fel-Pro PN 1011 on first the head and then the block to check for small holes located on the intake side of the cylinder deck surface. The holes should line up with holes in the cylinder heads. If there are holes in the block but not in the head, you should very carefully drill through the deck surface of the head or block to ensure that the steam-pocket points are open. Carbide drill bits work best, especially in high-nickel-content blocks. This mismatch can even occur on original factory engines and could account for engines with a sensitivity toward overheating or detonation problems.