The distributor gear on the...
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!
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...
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.
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.