Engine - Ignition System
Ignition Timing – Leave It Alone
In days long past, when engines had carburetors and ignition points, advancing the ignition timing farther than the
manufacturer’s spec, by turning the distributor, was the quick way to make more power. With fuel injection and
electronic spark advance, tampering with the distributor setting becomes a waste of time, and a source of problems.
This is because the actual time that the coil is firing and sending electricity to the spark plug is a very small
amount if time compared to how long it takes for the metal distributor rotor electrode to wipe across the metal
distributor cap electrode. The engine computer controls the spark event by grounding out the coil and firing it
for a tiny fraction of the time that these two electrodes are touching. And the computer advances the timing of
the spark from the baseline setting, to match the engine load and conditions to maximize performance. Under hard
acceleration, the electronic spark advance will be 30+°, and at idle and off throttle coasting, 0°. Twisting the
distributor won’t fool the computer, it will just retard its timing back to match what the engine actually needs,
and there is no performance gained. However, at idle and off throttle coasting, the computer will not be able to
retard the timing below the baseline setting that is set by the distributor position. Then the computer will
repeatedly advance and retard the timing against the baseline, trying to retard the timing by banging against the
lowest point it can go, trying continually to go lower. This is the root of the majority of the rev-and-drop and
erratic idle complaints.
Don’t mess with the distributor setting, make sure it is at the factory setting and then leave it alone.
Capacitor wires have been discredited for many years and are not worth discussing. Decent quality wires with good
EMI shielding are the best choice. For the DOHC engines, the spark plug boot is not common and not available from
Magnecore make a good fitting wire set, but the assembly is not very good. The spark plug end will eventually pull
away from the metal clip.
Accel’s 8mm wire set is better quality and the ends do not pull loose from the wires.
The original spark plugs used in the Geo Storm engine are conventional resistor plugs, with a steel electrode,
from NGK or Nippondenso. They work well but require cleaning once in a while to keep them at top performance.
Platinum and iridium have become popular with car manufacturers and have been advertised as “performance” plugs.
The truth is that platinum and iridium are very poor conductors of electricity and do not produce a spark as hot
as regular old conventional steel electrode plugs. The advantage of platinum and iridium is that they are highly
resistant to fouling, and basically never require any cleaning. So car manufacturers settle for a mediocre
performing spark plug with the advertising benefit of never having to be removed and cleaned. This allows car
manufacturers to say their engine requires a tune-up every hundred-thousand miles.
But for anyone actually desiring a performance enhancement, regular conventional steel electrode spark plugs
produce a higher spark, as long as the vehicle operator is willing to take them out every six months and clean
The only possible performance improvement with spark plugs would be an open face plug, such as the Torque Master
spark plugs. These are steel electrode spark plugs, which have been modified by removing the ground strap
(finger that extends over the electrode), and replacing it with a ground ring. The advantage is that the spark
does not have to travel around the strap as the fuel/air mixture is ignited, and the explosion within the
combustion chamber occurs a tiny fraction of a second quicker.
The original Geo Storm ignition coil is from AC Delco, and is pretty good quality, but these were not designed
to last 20+ years. If it requires replacement, there are some good options from MSD and Accel. The best of might
be the Accel Yellow Super Coil for HEI ignition. It is a direct bolt-on.
Multi-Spark – MSD and Accel
Multispark systems, such as MSD’s 6AL and Accel’s 300+ systems will provide hotter spark and more power.
Accel’s products seem to be based on AC Delco’s electronics and fit more like original, while MSD always seems
to end up looking more like a forced fit with lots of wire splicing.
One note of caution: While the Isuzu engine in the Geo Storm uses an AC Delco ignition coil, the coil in the Isuzu
engine is wired backwards. Any wiring harness will have to be custom made for the application, and integration
with the tachometer can be a challenge.
Conversion to coil-on-plug will provide better spark and more control over the ignition event. This will eliminate
thermal and electrical loss in the plug wires, and reduce coil recovery time (because each coil fires once per
cycle instead of a single coil firing four times per cycle).
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