rwd

I've studied the posts and TSB's, and as far as I can tell, the unit seems to have significant failure issues and is expensive to repair unless you do it yourself. It also seems like the design/layout make it susceptible to problems whenever a water pump fails, which seems to be every 60-70K miles.

Is this perception correct, or is the failure rate more like that of a common HEI unit but given additional prominence by the postings I've seen?

Also, is the '95 Optispark II unit the answer or do the miss and drivability issues referred to in the TSB occur with similar frequency?

Thanks in advance for your insights.

Corvette Kid

Depends on the year. The early version is more failure prone than the later one. Any LT1 can be upgraded to the later style and if you're changing it anyway, it's not that much more work and worth it IMO. Also, the later style is less expensive. You'll need the later timing cover, extend the cam pin and make minor wiring adaptations. Also, proper installation and care has a lot to do with either opti's life span.

aboatguy

I have a 95 that seems to be on Optispark number one. If the opti is like everything else that GM has done the 95/96 is probably pretty good, since it seems that once they perfect something they replace it with some new totally different system.
I still don't understand why after 40 years of SBC with rear mounted distributers, Chevy went to the front like a Ford.

Mike

STL94LT1

I have ~21,000 miles on my car, and third optispark. I just upgraded to the 95/96 unit. Hopefully, this upgrade will last a little longer.

bogus

space. They needed space for the intake plenum.

aqualung

I own a 92 LT1. The car was bone stock for 12 years. Original opti, 40,000 miles, no problems.

When I went with my heads, cam, headers package, I decided to upgrade to the newer vented opti.

Less than 2 months and 1,000 miles, I needed a new opti.

I don't know if it was because of the way it was installed or what. But I made sure it was installed correctly this time and loaded the connection with dielectric grease.

We will see how long this one lasts.

Mr Mojo

Everyone makes a big deal over the opti.
Has anyone ever neglected their distributor in any other car? What happens? They fail.

The opti may be more prone to failure if the water pump craps out, but not necessarily. I know of people who have blown the pump but left the opti in there.

On a normal distributor, how often would you change the cap and rotor? Has anyone ever got any kind of moisture in a standard distributor? If so, it will fail.

My '95 is on it's second opti and I have 131,000 miles on it. I replaced it around the 70,000 mark only because I blew the water pump and decided to do it all at once.

My '93 opti crapped out due to sitting around more than it was being driven, same for my GMC. Why? Condensation.

Redeasysport

I think that is a major factor Mojo a lot of these cars do not get driven on a regular basis. Probably the reason 95s last longer with some kind of venting.I have not had a distibutor car for quite some time but remember having to do the cap at least bi-anualy. The only real problem with the Opti is the price the price of the cap and rotor is ridiculous.Also the fear of failure and the amount of work probably makes people swap the unit out instead of just the cap and rotor.

One other point is remember no one comes here to brag about how good or long lasting thier opti is only when it craps out so it may seem they are total junk if you base your opinion on what you read here.

Mr Mojo

and yes the price is ridiculous

Tom Piper

To convert my '92 to the later Opti-Spark, I also had to change the camshaft -- my original camshaft had a center hole in the front that was too small for the later Opti-Spark to fit inside.

Be careful putting silicone grease on, or around seals of, the vented Opti-Spark, it can kill O2 sensors.

My original early Opti-Spark never had any problems in 50K miles. I only had 20K miles on my first vented Opti-Spark when it carbon tracked the cap.
But, I put AFR heads and a Crane cam (needed a new cam to use the later Opti-Spark) in when I went to the later Opti-Spark.
I think the added cylinder pressure of modified engines cause the need for higher voltage at the plugs and more carbon tracking of the cap.
That's why I decided to go with the Delteq, to get the high voltage out of the Opti-Spark.

Tom Piper

mitchcole

After looking at all the options - I went with the dynaspark. Yes it was $150 more than the stock one - but with a 92, I had the most to gain. It seemed easier and cheaper than getting the whole setup for the newer version.

If I had a 95 or 96, it would have been a tougher decision. It's been on for a year with no problems. That's not much of a test though.

mikey whipreck

Not that I want to argue with you, but I've never heard of, or seen, a standard distributer fail (neither of my two cars, my family's cars or my friends- of course none of us race or put extreme wear and tear on our cars).

ninetyfivevette

I think he's referring to the cap & rotor of a normal distributor. Since the OptiSpark has a conventional cap and rotor, they will definately fail sooner or later, but they all will. Since it is buried under the water pump, people don't change them until they are completely junk. The other failures (bearings, optical section) has a lot to do with poor bearings and poor location. A normal distributor gets to sit high and dry instead of under a water pump that leaks when it decides to die. Remember GM is not in the business of making cars that last 1,000,000 miles, but I don't think they intended on the failure rate some people are experiencing.

BrianCunningham

Nathan Plemons

The failure rate on the opti depends entirely on who you ask, personally I think it's just something that the LT1 haters of the world like to bitch about.

The failure of the water pump takes out many opti's prematurely. Many people who drive their cars very little replace the opti more often than those who drive them every day. They can crap out after 15k miles or they can last 150k miles. It all depends on the conditions under which they are run. My best advice though is to DRIVE THE CAR. The garage queens seem to have a much higher failure rate than the daily drivers. Often this is because the water pump failure rate is also much higher on the garage queens.

Also of notable mention is the way people treat the LT1. If an LT1 has a problem, people automatically assume it is the opti because of all the bad press. More often than not the opti is not the problem. This results in costly repairs only to find out that they weren't needed at all. Sure the opti fails, but it should never be the first place you look unless you specifically have a trouble code that points to it. Plugs, wires, and the coil all work the same old way.

mikey whipreck

Okay that makes sense

Draven

Mojo,

I'll step up to the plate and make the sacrafice. I'll drive your '93 for "problem prevention" purposes. ; )

-Joe

pwrful c4

I have a 94 with 75000 miles on it,I changed to a Delteq unit only because of the war stories about the Opti.I never had a problem with the Opti.

Corvette Kid

I changed my original at 93K the first time I did major engine work, but it was still performing flawlessly. I was going to throw it away but then thought I'd offer it cheap on the forum if it could help someone out. It may still be going for all I know.

SJW

I also suspect that the Opti can suffer from lack of use, and I strongly suspect condensation as the culprit. I bought my '94 last year when it had only 19,100 miles on the clock, and the Opti started misfiring within three weeks.

Conversely, I know others who drive their first-gen-Opti-equipped Corvettes daily, and have had no trouble with the Opti through over 100k miles of service. I suspect that the frequent temperature cycling of daily driving helps to bake condensation out of the Opti, unless it gets douched by a leaking water pump, etc. Purely conjecture on my part, but it's a hypothesis I'm beginning buy into.

IMHO, changing all of the parts required to bolt the second-gen Opti on a 92-94 car is not worth the hassle and $. The DynaSpark can solve the Opti problems for you, and should last a long time if installed correctly. If my DynaSpark ever fails, I'll probably bolt a DelTeq system on, and keep on rolling, if the optical portion of the DynaSpark is still operational. I didn't go for the DelTeq this time because I just didn't have any confidence in the integrity or longevity of the optical section of my original Opti.

The OptiSpark was a great idea, but poorly executed. The primary reason for moving away from the HEI system on the LT1 was to gain greater control of spark timing. The HEI simply couldn't give the ECM anything to work with other than a rather sloppy approximation of when to fire the coil (really not a lot better for timing than a fresh set of points/condenser), and it could give the ECM no data as to which cylinder was being fired at any given time. Additionally, the HEI relied upon proper timing adjustments by service techs, and was prone to problems with timing advance mechanisms as they aged.

In contrast, the Opti furnishes to the ECM true camshaft position, speed and acceleration data, which gives the ECM a great deal more to work with. Thanks to the Opti, the ECM can adjust timing, on the fly, for each individual cylinder. If one of the Knock Sensors should trigger, the ECM can retard the timing on only the cylinder that knocked.

In short, the ECM can optimize ignition timing for each cylinder under a broad range of operating conditions. This is only possible because the ECM knows true camshaft position, speed and acceleration (thanks to the Opti), as well as engine coolant temp, intake mass air flow, manifold pressure, vehicle speed, etc. Without all of those sensors, and a replacement for the HEI, none of this would have been possible.

The LT1 produced the best brake specific fuel consumption figures (a good measure of combustion efficiency) of any engine of its type in its day. It was a brilliant leap forward in terms of combustion management, and the Opti was a crucial part of that. The Opti was a huge transitional step in the engineering evolution that carried us in the direction of today's Distributorless Ignition Systems.

The shortcomings of the Opti are almost exclusively tied to its placement on the engine. The engineers wanted to couple the Opti directly to the camshaft, for obvious reasons given their design objectives, but bolting the unit to the timing cover (and beneath the water pump) took what would otherwise have been no problem at all and turned it into big trouble when service became necessary -- and increased the likelihood that it would become necessary, when coolant dumped onto the unit.

If they'd placed the Opti where it was readily accessible, this simply wouldn't be an issue for us. Obviously, their failure to adequately engineer the unit for durability greatly exacerbated all of the problems.

IMHO, the Opti deserves to be cursed for these two engineering blunders. But it also deserves to be admired for the great leap forward that it truly was. It is far from being entirely bad. To be fair, we probably should view our relationship with the Opti as one of those love/hate things...

Be well,

SJW