what dose it do??How do u know when its going out??

1990 doesn't have one

thanks for lettin me know

Despite you not having one, for those of us that do it's basically the distributor just in a different design. It has the little thing inside that goes around and around and sends the spark through the wires to the plugs.

It was also put in a very convenient spot for Gm to make money on repairs.Bad opti replace opti,leaking water pump,replace pump and opti.Plug wire change,too hard for some take it to the dealer.
They could have at least put a drain around the opi from the weep hole

How do u know when its going out??

Engine stops running.
Have a habit of dying real fast with little notice when they go

There is nothing wrong with the design of the Opti; many Japanese cars run the same unit without problems
But they are not mounted down low under a waterpump that can leak

Despite you not having one, for those of us that do it's basically the distributor just in a different design. It has the little thing inside that goes around and around and sends the spark through the wires to the plugs.

:thumbsup3: PITA too!

Found this - might help.

Opti-Spark Ignition System Tune-Up
Don't be afraid that you can't even see your distributor. With new MSD goodies, you too can tackle the Opti-Spark tune-up.
By Terry McGean
Photography by John McGann

The engine bay of a '94-'96... read full caption

The engine bay of a '94-'96 Caprice/Impala is easily the most spacious of any LT1-equipped car, yet it can still be intimidating, particularly if you're not one to wrench on late-model stuff. Buried in there is the Opti-Spark ignition distributor, itself a bit of a fearsome device, but servicing it is no big deal, as you'll see.Man, time flies. It seems like just a couple years ago when GM introduced the first major renovation of its small-block, but of course, that was back in 1991 for the '92 Corvette. At the time, one of the big deals of the Gen II engine was the Opti-Spark ignition system, which was driven directly off the cam and treated the engine "like eight one-cylinder engines," according to GM, in reference to the system's agility in constantly adjusting ignition timing based on need. The Opti-Spark system still used a distributor and conventional spark-plug wires, but it seemed to be considered a maintenance-free device, at least if the 100,000 spark plugs were any indication. But now the youngest of LT1-powered cars have been on the road for about nine years, and it's pretty common to see them with well over 100K on the clock. What's more, time has shown that LT1s tend to be hard on their ignition systems, if only because the plug wires are routed behind the exhaust manifolds where they are frequently baked prematurely. The resulting increases in resistance can in turn stress the distributor cap, and that's where a lot of guys get hung up.

If it isn't the fear of the unknown causing hesitation in tearing the system open, it's the lack of available parts, or at least their unusually high cost. Apparently, since GM didn't intend for this system to need frequent maintenance, the cap and rotor were not initially available on their own, and a whole new Opti-Spark unit had to be purchased. Later, the cap and rotor were sold separately, but often at a price that made the complete Opti unit seem more attractive. Now MSD has stepped up to offer its own version of the Opti-Spark cap and rotor, and by the time you read this, a complete, billet-housing Opti-Spark distributor. Both the cap-and-roller sets and complete distributors will be offered in early and late designs to cover all LT1 applications. We'll tackle the simple tune-up parts and illustrate that getting the job done on a Caprice/ Impala, isn't so bad. Have a look.


Within a few minutes, and... read full caption
Within a few minutes, and with a few twists of a flathead screwdriver, the air inlet ducting and radiator hoses are removed (obviously, make sure the car is cool first), making the front of the engine a little less cluttered. The bad news is the water pump, air pump, and crank balancer all have to come off to get to the Opti unit, but it really isn't that tough once you know where the fasteners are and the removal procedure.
If GM hadn't used one of the... read full caption
If GM hadn't used one of the water-pump bolts as a mounting stud for one of the air-pump bracket's mounting ears, the air pump could stay in place while the water pump comes out, but it did, so it does. There are three bolts holding the electric air pump to its bracket--a 10mm socket easily removes them, and then the pump can be swung out of the way with its hoses and wiring intact.
The air-pump bracket has three... read full caption
The air-pump bracket has three mounting bolts, and a 916 will get them if you don't have a 14mm socket. The bolt over the water-pump stud accounts for one, another is in the center of the bracket, and a third is tucked behind a spark-plug wire. Pull the second wire from the top on the left bank and stick the socket through to the bolt.

what dose it do??How do u know when its going out??
A little more reading. Good info on Optispark.

Why does the Opti-Spark Design Need Improvement?


In theory, the Opti-Spark design is good. In fact, high-resolution engine speed sensing leads to extremely accurate ignition timing, and was a rare occurrence even on high-dollar sports cars back in 1992. In practice however, quite a few things are problematic with GM's execution of the Opti-Spark distributor.

First and foremost, there are the typical wear, heat, and moisture problems associated with a distributor cap and rotor. Since most Chevrolet V8 engines feature an easily accessible rear-mounted distributor, it is not a big deal to change the cap and rotor every 50,000 miles (or sooner in high performance applications). Plus, the availability of standard-style cap and rotor assemblies makes them extremely cheap. These facts do NOT hold true for engines with the Opti-Spark distributor.

From an accessibility standpoint, both the water pump and the crank pulley need to be removed in order to gain access to a failed Opti-Spark distributor. On Camaros and Firebirds in particular, this is not a quick (or fun) job.

From a reliability standpoint, the environment at the front of the engine is notoriously harsh for things like heat, water, and debris (not to mention other variables like leaky front crank seals and worn, leaking water pumps!), but the Opti-Spark distributor is not even sealed on 1992-1994 models! Later versions of the Opti-Spark incorporate a seal and venting provision, but are by no means free of problems.

From a cost standpoint, the Opti-Spark units can retail for well over $400, depending on model year. Dealers have been heard to quote over $1000 (parts and labor) to replace this item!

To add insult to injury, the Opti-Spark distributor uses a "Correct-a-Cap" design that places the spark plug wire terminals on the proper side of the engine for easy spark plug wire routing. To do this, the terminal traces molded into the distributor cap must come extremely close to one another, which leads to premature arc-over in high-load applications and applications using constant high-voltage (Capacitive Discharge) ignitions. Not good.

But not all is defective on the Opti-Spark distributor. Inherently, the optical sensors are fairly robust. For most applications, the sensors are not the cause of most problems. To prove this fact, Mitsubishi manufactures the Opti-Spark sensors, and variations on these same sensors can be found on most late model Mitsubishi and Nissan applications. Reliability problems with the optical sensors on the Nissan and Mitsubishi vehicles are simply not present in anywhere near the same quantity as the LT1 and L99 engines. This would suggest that the main problems with the Opti-Spark distributor are not the sensors, but the cap and rotor.

Very informative and helpful! So does the Opti-spark actually have a 'cap and rotor'? I can understand the rotor being the part in the middle that actually spins and causes the spark, but what's the 'cap'? I'm wondering because I need mine replaced as soon as I can afford it. According to the mechanic I need new plug wires, possibly cap and rotor, and distributor I think, and a leaky seal which is the front crank, water pump, or distributor seal. I just need a basic definition/ breakdown of what the Opti-spark actually consists of. I thought it was just the housing with the terminals, then the little thing at the center that spins and controls the spark timing. How much more is there to it?

From what I can tell think of taking a full size cap and rotor and squish it down like a pancake.
The last time my car was on the rack grab a flashlight and look up underneath above the crank balancer its the best view of the unit. Myself I'm not even going to try and change it.I'll gladly pay the grand lol.

I can understand the rotor being the part in the middle that actually spins and causes the spark, .... I thought it was just the housing with the terminals, then the little thing at the center that spins and controls the spark timing. How much more is there to it?

The ECM controls the spark timing .The little thing in the center (rotor ) only "distibutes" the spark which is made by the external coil .Nothing in the Opti " makes" the spark .
Two seperate parts ;
the optical sensor ( where the Opti name came from ) that tells the coil when to make the spark and the cap /rotor that sends the spark from the coil to the right plug

Serious Tech explaination here
http://www.gmhightechperformance.com/tech/0310htp_lt1_ignition_system_understanding_modifyin g/index.html

Myself I'm not even going to try and change it.I'll gladly pay the grand lol.

How to with pics:thumbsup:
http://www.corvettefever.com/howto/16758/index.html
http://www.carcraft.com/howto/ccrp_0603_opti_spark_tune_up/index.html

Cheaper to buy this @ $785 No more Opti problems ; it only works as a crank trigger
http://www.delteq.com/default.htm

Ah I see. I agree though I'm not touching the thing lol. I'll get frustrated and break something. I'd rather pay to have it done and have the confidence that it's done right and that I didn't screw something else up in the process.