Ignition decision troubles
MrBrown
07-17-2006, 02:23 AM
What are my options for replacing my ignition module and coil? Can I just buy an aftermarket coil and module, or does it have to be a special one since my car is an 84 with the computer carb? In the summit catalog I found Accel coils and modules for kinda cheap. Also, would it help performance/economy wise?
silicon212
07-17-2006, 02:38 AM
What are my options for replacing my ignition module and coil? Can I just buy an aftermarket coil and module, or does it have to be a special one since my car is an 84 with the computer carb? In the summit catalog I found Accel coils and modules for kinda cheap. Also, would it help performance/economy wise?
As stated in another thread, Accel coils, modules, caps and rotors don't help at all for around town driving where they'd be just throwing money away. The stock HEI unit has a limitation of about 5500 RPM before it starts getting really flaky - acting as a de facto rev limiter. What the Accel stuff does is broaden the RPM level of the HEI distributor. It's a poor man's Mallory or MSD.
Inasmuch as what you can use on the distributor, you have to use a module that works with the computer (these distributors' advance curves are controlled by the ECM and not mechanically).
A somewhat more reliable unit is available that drops in - all you have to do is rewire the connectors for the computer interface and module - it's the so-called "TPI distributor". It's also an HEI system, so wire for wire it's the same, but it uses an external coil, a small-diameter distributor cap and a rotor that pushes onto the shaft like other makes (Ford, Chrysler etc). It's the distributor used on 1987-93 Caprices with 305/350 engines. You can get this distributor/coil package from a junkyard car - cut the wires from the harness so that you have them along with the parts - on the power interface for the coil, you might find one that has a pink wire by itself or a pink and a white wire. The pink wire is hot for the distributor - this wires into your current HEI power lead. The white wire (if it's present) will have a quick-connect on the end - this is a tach lead. There is also a pink and white harness that goes between the coil and distributor. Then there's the 4-wire interface on the distributor itself - you can splice this in place of your current one. The colors are like for like.
Driving around town, you're not going to get any performance or economy increase with any distributor unless your current ignition system is in need of serious help. Performance ignition systems will be more reliable than regular HEI at higher RPMs, and in the case of stock HEI, will enable the engine to climb above 5500 RPM, but they won't do squat around town for you. Anyone who tells you otherwise doesn't understand the definition of snake oil.
As stated in another thread, Accel coils, modules, caps and rotors don't help at all for around town driving where they'd be just throwing money away. The stock HEI unit has a limitation of about 5500 RPM before it starts getting really flaky - acting as a de facto rev limiter. What the Accel stuff does is broaden the RPM level of the HEI distributor. It's a poor man's Mallory or MSD.
Inasmuch as what you can use on the distributor, you have to use a module that works with the computer (these distributors' advance curves are controlled by the ECM and not mechanically).
A somewhat more reliable unit is available that drops in - all you have to do is rewire the connectors for the computer interface and module - it's the so-called "TPI distributor". It's also an HEI system, so wire for wire it's the same, but it uses an external coil, a small-diameter distributor cap and a rotor that pushes onto the shaft like other makes (Ford, Chrysler etc). It's the distributor used on 1987-93 Caprices with 305/350 engines. You can get this distributor/coil package from a junkyard car - cut the wires from the harness so that you have them along with the parts - on the power interface for the coil, you might find one that has a pink wire by itself or a pink and a white wire. The pink wire is hot for the distributor - this wires into your current HEI power lead. The white wire (if it's present) will have a quick-connect on the end - this is a tach lead. There is also a pink and white harness that goes between the coil and distributor. Then there's the 4-wire interface on the distributor itself - you can splice this in place of your current one. The colors are like for like.
Driving around town, you're not going to get any performance or economy increase with any distributor unless your current ignition system is in need of serious help. Performance ignition systems will be more reliable than regular HEI at higher RPMs, and in the case of stock HEI, will enable the engine to climb above 5500 RPM, but they won't do squat around town for you. Anyone who tells you otherwise doesn't understand the definition of snake oil.
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