When a phone caller asks me to diagnose a problem in his FI unit, I always give him the same initial advice: “First, don’t take the unit apart”. I say that because many fuel injection problems are actually in the ignition system. There’s usually something significant that must be addressed beyond replacing the points, rotor, cap, and condenser with new parts.

Even after fifty years, the distributor cross-shaft gears and mainshaft bushings seldom have much wear IF the oil feed tubing has never been disconnected. But many times a past owner will have plugged the oil feed line while he ran an FI distributor with a carburetor. This is a serious mistake. The distributor needs that lubrication even when it’s not powering the gear pump. Without the extra oil, the gears can wear out in the center of the teeth. You can tell if the gears are still good by looking at them. If the teeth are the same thickness throughout their length, then they’re full strength. A shiny face is okay. However, if they’re noticeably thinner in the middle, they should be replaced.

If so equipped, you must make sure the vacuum advance is still working and that it has the correct specs for your model year. The hexagonal ’57 – ’61 vacuum canister is no longer available new, but Standard Products still sells B22 canisters for ’63 distributors and B28 canisters for the ’64 – ’65 distributors. By the way, these new canisters don’t come with a rubber bushing to limit the amount of advance. You have to provide that yourself.

The contact points must have high tension springs to avoid point bounce at engine speeds over 5,000 rpm. I normally install Standard “Blue Streak” ignition parts. Standard has consolidated some part numbers over the years, but the good numbers used to be DR2336XP for ’57 dual-point distributors, and DR2270XP for the later models. You’ll have to cut off the lubrication wick on one set of the DR2270XP points to install them in a ’58 – ’62 dual-point distributor. I do that with a Dremel tool cut-off wheel.

I’ve found that some ’58 – ’65 FI distributors are worn in a way that makes the point dwell change at high rpm. This can be an issue if the dwell drops by more than 5 degrees. This problem could be due to up-and-down movement of the point cam on the mainshaft, or it might happen because of a warped lower housing… I just don’t know. The only sure cure is replacing the points with an electronic spark trigger. I normally use the M & H single-wire design because I think it’s very durable. The Pertronix set-ups work fine too… well, right up until the time they don’t work at all. Take your pick.

Having the right coil and ballast resister is important too. But you shouldn’t trust the part number to tell you if the coil is right. For years, one vendor in particular has sold genuine Delco coils with the right numbers but the wrong resistance across the primary windings. Evidently he’s been taking old Delco coils from God-Knows-What vehicles and putting new metal skins over the bottom can. Another vendor sells new Delco coils made in China. These overseas coils may work fine with brand new plugs, but they don’t provide a strong spark and aren’t reliable over time. Check the electrical resistance across the small terminals on top of the coil. Your ohm meter should read 1.5 to 2.1 ohms when the coil is cold. If the resistance is much less than that, you’re going to burn your points by passing too much current through them. If it’s much more, you’re going to have a high speed misfire because of a weak spark. The same test can be used for the ballast resister. It should have 0.3 to 0.6 ohms of resistance when cold.

Here’s what I think of reproduction plug wires from Chicago and modern AC spark plugs: they suck. If you have those repro plug wires because they “look correct” with the fake dates, please use them for shows only. Eventually they will cause misfiring at high speeds. The same goes for AC resister type spark plugs. Since AC no longer makes a non-resister design, I suggest you use Autolite #295 plugs. Those plugs are equivalent to the old AC 46 heat range.

The mechanical advance curve is determined by the length of the slot in the point cam, the thickness of the bushing on the limit pin, the strength of the springs on top, and the mass of the weights that stretch the springs. I seldom receive a distributor with all those parts working properly. Some of them have usually been exchanged for aftermarket parts that don’t fit or work right. In fact, most of the original factory advance springs don’t work right either. They allow the mechanical advance to start below idle speed. That gives you an erratic idle speed as the engine hunts for a stable amount of spark advance.

I’m not going to list all the weird distributor aberrations I’ve come across. It would just depress you. It seems that all Delco fuel injection distributors were owned by Gyro Gearloose at one time, and Gyro “improved” them to the point of not running right. My advice is simply this: make sure your distributor is working properly before you even think about tearing down your fuel injection. You’ll probably find at least some of the problems I routinely encounter.