If you are buying OEM, there is no way to beat Chris at Superior, even with shipping... Great service and even better prices...

 

Even though I am a Accel/EMIC dealer. I would still go for the MSD unit. It is much more robust. The Accel from what I can tell is equal to a OEM GM unit.

 

I think i tend to believe Jesse, he has many people saying nothing but good about his abilities and judgement !

 

Saw some MSD Optis on ebay last night for around 127.00. I know nothing about them, but again thought I would pass it along - it might help someone out.

 

Probably the cap&rotor not the entire opti.

 

The new MSD opti looks pretty sick. I like the new sensor they use to replace the optical unit.

Really the Opti gets a bad rap, they aren't THAT bad.. As long as they are vented and you keep water off them most of them last 100k miles.

 

You didn't entirely miss the boat. That Accell Opti WON'T FIT Gen. 1 cars like yours, only Gen. 2 Opti-equipped cars.

 

I have never heard of an optical sensor failing that was not contaminated.It is probably the only part of the OEM opti that was done right.Figures it was made by Mitsubushi and not GM.

 

The optical sensor on mine failed. The wheel the sensor uses rusted up

 

And what part of what I said did you not get Alvin?Rust is caused by contamination in the opti(moisture) that should not be in it.I will bet there was nothing wrong with the sensor itself.If the slotted disc could have been replaced it would have worked just fine.Even when contaminated the lenses can be cleaned off and they will work.The problem is plugged slots on the disc.This was to point out the lack of need for MSD to re-invent the wheel so to speak.

 

I consider the slotted disk a part of the sensor.

The rust comes from the NOx that is stored in the optispark when a arc happens and not vented like it should be.

 

Actually Ozone is the spark by product.How can a mechanical part of the opti be considered a part of the sensor?I stand by what I said the optical sensor( emitter and reciever) is a very robust little device.The code 16&36 indictate that it is unable to read the disc either due to contamination(rust,coolant) or mechanical damage(shattered rotor).

 

My '95 Vette is a daily driver I've got about 164,000 on the car with the original Opti.

 

I had 55K miles on my stock '92 LT1 with an original unvented Opti-Spark and no problems.

I, then, tore the motor down and put AFR heads, Crane cam, roller rockers, and a '95 style, vented, Opti-Spark on it.
That vented Opti-Spark lasted 20K miles and the cap was carbon tracked badly. And, there was no sign of moisture in the Opti-Spark.

It is a known fact that higher cylinder pressure (higher horspower = higher cylinder pressure) causes more stress on an ignition system because it takes a higher voltage to fire the plug gap. And, that higher voltage puts more stress on everything on the secondary side of the ignition system -- including the cap and rotor of the Opti-Spark.
It is my belief that modified engines will have a greater potential of having Opti-Spark problems.
That is why I decided to go with the Delteq -- to get the high-voltage out of the Opti-Spark.

As an added side note:
You can think of the spark plugs (and their environment, such as cylinder pressure) as a high-voltage regulator. The secondary potential of the ignition system will not go higher than what it takes to fire the plug. Once the voltage fires the plug gap and current starts to flow in the secondary, the voltage will not build any higher.
If you pull the plug wire off of the plug, that is when the highest voltage will be available on the secondary.
In fact, it was not uncommon for the Delco platinum plugs to have the platinum "pucks" fall of of the plug electrodes causing the plug gap to increase. This causes the secondary voltage to build higher than necessary and this voltage is placed on all components in the secondary side of the ignition system -- including the Opti-Spark cap and rotor.
I actually suspect that the pucks falling off and plugs with excessive gaps have contributed to the demise of many Opti-Sparks.

The Northstar coils, used in the Delteq system, are so potent that they can arc internally and destroy themselves if the plugs are not connected to limit the voltage from rising.
Part of the Delteq testing procedure tells you to disconnect the plug wires from the coils and crank the engine to confirm the sparks at each coil.
Don't do this for too long or you may be buying a new coil.
A waste spark system (four coil system on a eight cylinder) has to fire two plug gaps in series. So, if your plug gaps are .050", each coil in the waste spark system sees a total gap of .100". But, since one cylinder is on the compression stroke and one is on the exhaust stroke, only the cylinder on the compression stroke sees a very high pressure. That cylinder on the compression stroke is the one that determines most of the voltage on the series system.

Tom Piper

 

Can you explain to me how the ignition system knows what's going on in the cylinders?

 

Kid I think he is refering to the fact that higher air pressure changes the electrical resistance in it.That in turn raises the votage required to bridge the gap on the plug.I could be wrong but mabey not.

Anyway the stock coil produces ~20kv IIRC and the gap fires at ~10kv but Duration of the spark is more important than voltage and if the voltage required to bridge the gap increases the duration decreases.It also puts more stress on the coil when it is required to fire at higher voltage(heat) and will shorten the life span of the coil.

We all know the rotor in the opti does not touch the cap and actually arcs across and since the voltage across the gap resistance is higher at the plug causing higher voltage arc so will be the arc inside the opti.It will cause the rotor to burn and other bad things over time which may lead to premature failure of the opti.Think of a welder turn it up too high it melts the metal.

 

That about says it all.

The only thing I can think of adding is:
The secondary side of an ignition system typically has a high impedence.
It is designed for high voltage, but not high current capability.
That is why you can grab the spark plug wire with 20+ kilo volts on it and not end up in heaven. You will feel it, but it won't kill you.
When the current starts flowing through your body, the voltage is essentially dropped throughout the resistance of the secondary side of the ignition system. Your body does not see the voltage and current needed to fry it.
Don't try that with a 20 KV source from the power company -- that source has the current capability to maintain 20 KV with high current.
You will fry like a hot-dog.

That secondary resistance (thousands of coil windings, resistor plug wires, resistor plugs) limits the current and drops the voltage.
This is exacly what happens once the spark plug gap is bridged by the arc and current flows. But, until that plug gap is bridged, the secondary sees an open circuit and will build voltage to the max capability of the ignition coil.

Tom Piper