Ignition Upgrade For Jeep 304 & 360 CID V-8 AMC Engines

Main Upgrade Information | High Performance Upgrade Explanations
Tips, Tricks & Troubleshooting | 1977 and Older Vehicles | Part Numbers

TIPS, TRICKS & TROUBLESHOOTING

DISTRIBUTOR:
The stock Motorcraft distributor is just fine for any stock application. It is also just fine for any engine that operates below 5,000 RPM. Expensive billet distributors are not needed for stock or slightly modified, applications.

The centrifugal advance springs can be accessed by, Taking the distributor out of the engine, Taking the vacuum advance off, (don't loose the little 'C' clip!) Taking the two screws out of the floor plate, and lifting the entire shaft and advance assemblies until the weights and springs are visible. DO NOT hammer on the shaft! Stand it up in parts cleaning solvent until you can pull the shaft out by hand. It may take a day or two of soaking and pulling, so be prepared. You must grease all friction surfaces before reassembly. (Top and bottom bearings, and the thrust washers above the drive gear)

You DO NOT have to use the same type of spring on both sides. It is the total spring pressure that determines the centrifugal advance. (Heavy/ heavy, heavy/ medium, medium/ medium, medium/ light, etc.)

An even number of teeth on the distributor gear means no front or back, so the distributor gear can go back on either way. If you have an odd number of teeth on the drive gear, make sure you mark the gear to align with the rotor nose. (I do them all this way, no matter what it comes off of)

GO EASY ON THE DRIVE GEAR! The drive gear is made of cast iron, and is pretty fragile. Don't clamp it in a vise too tight, and don't hammer on the gear when you take the roll pin out. I always use a vice to press the new roll pin in on reassembly.

DISTRIBUTOR CAP & ROTOR:
The distributor cap and rotor should be a quality set, with brass terminals in the cap, and a brass blade in the rotor nose. This is one area that should not be overlooked. In the cases of the 'Can' style coil, a distributor cap with aluminum terminals will offset any increases you may gain with a premium coil. So protect your investment, and get the premium cap & rotor.

PLUG WIRES:
What I try to look for in a set of plug wires is good boots & connectors on both ends, low resistance, and good RF noise suppression. The three basic types of wires on the market right now are:
1. Solid Core: Never Ever use solid core wires on anything with an electronic ignition!
2. Fiber/Graphite Core: Accel, Taylor, Jacobs and the $20 lifetime warranty brand of discount store wires fall into this category. These wires are perfectly all right if you do not plan to optimize your ignition system, and want to stay with the stock type technology developed in the 1940's.
3. Helically Wound Core, or Spiral Core: This type uses a thin wire wrapped around the resistor core, and makes a good RF choke, while conducting more of the spark energy where it can do the most good, the spark plug.

The highest output wires with the lowest resistance we tested were made by MSD.

SPARK PLUGS:
Extensive testing produced no clear results with spark plugs. The very same engine may run best with one kind of plugs, and an engine built exactly the same in every way may do better with a different kind of plugs.

There are some basic guidelines that stay true no matter what the engine, or application.
1. The more expensive plugs DO NOT perform better than the standard brands.
2. The 'Gapless' or 'Horizontal Gap' spark plugs require the flame front to travel down, and then turn 90 degrees to travel correctly across the combustion chamber.
3. Standard Spark Plugs orient the spark in the correct direction, and inject it deep into the combustion chamber.
4. Indexing spark plug ground electrodes on anything but the highest performance output engines is a waste of time and effort. With modern plug gaps, and ignition energies, the ground electrode doesn't present enough of an obstacle to worry about.
5. I have never seen any extra horsepower, torque, longevity or reliability out of the 'V' Split ground electrode spark plugs.
6. If you pry down on the center electrode to gap the plugs, you have a 50/50 chance of just destroying the plug internally.
7. If you ever drop a plug on anything hard, throw the plug away and get another one. It's not worth the $1 each to take a chance on loosing 1/8 of your total horsepower.
8. Always use an 'Anti-Seize' type product on the threads before installing spark plugs. It insures the threads don't seize in the head, and it insures a good electrical ground to the head.
9. Make sure your spark plug wire connectors 'Snap' into place. If they don't 'Snap', figure out how to 'pinch' them closed so they do 'Snap' into place. A solid connection at the plug head connector is essential to proper function.
10. Remember to use a little Dielectric grease on the spark plug porcelain to 'seal' any voltage leaks.

DURASPARK MODULE:
There are at least a dozen kinds of DuraSpark modules on the open market. The modules are identified by the color of plastic grommet that connects the wiring to the module housing. The most common is the 'BLUE GROMMET'. The 'Blue Grommet' module is the one most Jeepers will want to use.

All DuraSpark modules are full 12-volt units. Anything less than 12 volts and the module becomes unstable. (Ask anyone driving a Ford that threw an alternator belt)

All but the Ford SVO Dura Spark units, and a couple of aftermarket units, become unstable at around 3,500 RPM, and can fail completely at around 4,500 RPM. Most stock or mildly modified vehicles will not operate long enough above 4,000 RPM long enough to uncover the flaw. (The only reliable ignition above 6,500 RPM I know of is MSD 6,7.8,9, & 10 series, and they are good to over 15,000 RPM)

The black wire that comes out of module and goes to the four-wire connector is the ONLY GROUND FOR THE MODULE. It normally grounds through the distributor wiring. I always splice into the black wire, and solder a second lead to it, and ground it to a solid engine or battery ground on the racecars.

The DuraSpark module can be reliably triggered by any of the factory, and most aftermarket, magnetic pickup coils, so it can by used to get you home in a pinch no matter what kind of electronic ignition you have.

THE IGNITION COIL:
There are two basic ignition coils to choose from. Both can be interchanged at will, as there are no differences in primary resistance, and both are full 12-volt coils. The choices are:
A) The 'Canister' or 'Can' or 'Volcano' coil
B) The TFI (Thick Film Integrated) or 'Square' coil.

Like most of the automotive ignition systems, progress sense the 1920's has been slow. The TFI coil is a large improvement over the canister coil, but should have been done 45 or 50 years ago when the technology first became available.

'Can' coils have several draw backs, but the biggest two are the current outputs on the high voltage side are lacking. These are oil filled for the most part, and must be operated with the high voltage tower pointing up, or coil damage can result.

Switching to the TFI (Thick Film Integrated) coil will effectively double the usable spark energy, and can be mounted in any orientation. The TFI coil has the added benefits of having the 'Tower' style high voltage terminal and the high voltage terminal much farther away from potential grounds than the 'Can' type coil.

When upgrading to a TFI coil on a factory ignition system, some attention has to be paid to the voltage POLARITY. If you hold a 'Can' coil with the Primary 'horseshoe' connector at the top, above the high voltage tower, the Primary Green wire, Negative, is on the Left, and the Primary Red wire, Positive, is on the Right.

If you hold a TFI coil with the Primary connector at the top, and the high voltage tower at the 6 o'clock position, the wiring hookup is reversed. With the TFI coil, the Primary Positive, Red wire, is on the Left, and the Primary Negative, the Green wire, is on the Right. If you look into the Primary Connector, the polarity is usually marked there (/-).

(See the attached Wiring Diagram) ?

TFI COIL BRACKET:
The TFI coil bracket can be salvaged off of any V-8, V-6 or I-6 engine that used it. All Ford cars past 1986 had the TFI coil (according to the interchange book), so there should be an abundance of coil brackets in the junkyard and parts houses. (The one I used was from a 91 Mustang with 302 V-8.)

Fabrication of a bracket is pretty easy with any kind of metal. I have seen a dozen done out of 1" X 1" X 1/8" angle iron about 3" long, and these work as well as anything I have ever seen. They take about 20 minutes to fabricate with a Dremel tool or file, hand drill, and hack saw.

A good ground on the bracket and coil frame will help keep the RF noise out of your radios.

WIRING HARNESS:
If you intend on upgrading from breaker points, Prestolite or whatever ignition, you may have to fabricate a wiring harness, or you may want to modify your wiring harness for a MSD or TFI coil, or what ever...

Proper connections are a three step process:
1. Mechanical Connections. Use UN insulated metal crimp connectors, solid copper if you can find them, and a good set of crimping pliers. Cheap crimpers can do more damage than good. Never use aluminum connectors on anything.
2. Electrical Connections. Many people think that the mechanical connection will provide the electrical connection. Not true in all cases. The only way to be sure is to solder all connections with silver bearing rosin core solder. I can recommend Radio Shack P/N 64-013. It will stick to almost anything, melts at an acceptably low temperature, and does a great job of tinning the wire.
3. Heat Shrink Tubing. The tubing slipped over the wire before the connection is made, and pulled into place when the connection is finished. The Tubing shrinks down on the wire to seal moisture out of the connection. If the correct tubing is used, and it's installed correctly, the joint should be trouble free for the life of the vehicle.

Look in the parts lists to find the connectors to make your own wiring harness.

Berkeley | Back to FSJ Wagoneer