It did not stop me. If you get an opti with the mistubusi sensor and put together with the correct sealant and is vented it is very reliable. I recommend the optidoctor here or on ebay. Lots of cars with original opti running fine at 100K miles.

 

I have one since new a 93. When it is running i love it! The clam shell hood the used ones if bought fight are a steal. There are plenty of parts new and used and being as old as they are now always keep spare parts like a opti and a water pump on the shelf. The 93&96 are my choices if bought used.

 

IT's an overblown issue to be sure, and lots of problems are blamed on the opti that are really caused by something else. Also, while it's possible to get water leaked inside an opti, the more likely failure mode is condensation or ozone buildup from the electrical charges passing through it. The vented opti that came in 95/96 resolved this. As Whaleman wrote, if you get an LT-engined C4, and if you actually get an opti problem with it, replace it with a properly sealed and vented unit and you are probably good for the rest of the car's life. It's also not as bad a job to replace an opti as some people make it out to be.

In short, I would not let opti fears dissuade you from buying a C4 with a vastly superior LT engine.

 

Yes, you will read a ton about the Achilles heel of the LT-1.

Let me just say up front, I am not a mechanic. I have replaced three Optisparks so far on two LT-1 Corvettes so it's just my opinion after a measly 3 years of ownership.

What do you plan to do with the car? If it will be a garage queen or a track car, you're good. A daily driver or long distance trip car might be different.

How are your mechanical skills? Or how deep are your pockets to pay a mechanic? A good mechanic with the right tools can swap it in 2 hours. My first took 2 months. All because of the Harmonic Balancer that has to come out.

Once you've done the swap and slathered anti-seize all over the HB mount, future swaps are relatively painless. My second time took less than a day.

The Optispark can and will leave you stranded. Often with little or no warning. My '96 has been towed home three times. Not a question of IF, simply a question of WHEN.

Do you feel lucky?

Then there's the bad news. GM no longer makes the Optispark. Mitsubishi no longer makes the coveted optical sensor. Cheap Chinese junk abounds.

There's the fellow who conferred a doctorate degree upon himself for rebuilding Optisparks. He will show you a video of it working on his bench before shipping. Well, they all work right up to the point where they no longer do so meh.

Every one of them is a crapshoot. The one I'm running now is made by AIP (Bakersfield) and it can be bought with a 90 day warranty on Amazon for $99 or a 2 year warranty at Sac City for $160.

My previous now dead Optispark lasted about 16 months (on a one year warranty) and came highly recommended from Petris Enterprises for $350.

Some folks put the Mitsubishi sensor from their original Opti into a Chinese model. Others swap cap and rotor and cross their fingers.

That's my lousy 2 cents on the topic. Long trips in my vette are virtually non-existent as my butt puckers just thinking about the inevitable fail to come.

Happy hunting!

 

It would be interesting to have a sticky running on C4's where owners who haven't had issues could post their milage and length of ownership to put some balance into the forum. Owners typically come to forums with problems not when their car is running well. It would be especially interesting in regards to the Optispark units!
I understand that the Optispark is used on the same engine in other GM vehicles, do they have the same issues or is it more prevalent in the Corvette?

 

From what I've read in other Chevy forums, yes. BUT the tight physical access to the Optispark on the C4 is uniquely challenging. Impalas have room for a family of four in that engine bay. I had to use an air hammer on the harmonic balancer from underneath and behind. No puller I could find would fit between the balancer and the steering rack.

A sticky would be nice. But If there are folks running the LT-1 without issue, they have had all the opportunity in the world to chime in. It is a distributor, so it has a limited lifespan and the replacements are (all together now) a crapshoot.

Do some folks misdiagnose the issue? Without a doubt. I'm sure many Optispark have been replaced when the coil or ICM were the real culprit. But the bottom line is they will fail at some point, they give subtle or no warning, and you have shizzle for replacement options.

If I'm ever in the C4 market again, I would look for a '91. And it would probably have a whole new pile of issues. So I'm watching the C6 prices drop...

 

I bought my 95 13 years ago. It had approx 30K on it at the time. I used it as a year round daily driver.

At 70K I had the entire ignition system replaced with new parts (including MSD opti & coil) when I had the LT4 hot cam kit, long tube headers and some other items installed.

The car now has 135K on it and no opti issues.

For someone like the Original Poster .... if you are considering buying a C4 for the first time I would strongly encourage you to invest $20.00 and buy yourself a copy of Mike Antonick's Corvette Black Book and go through the pages for 1984 - 1996. It makes it real easy to see what options were available with each year, what improvements were made to the car each year and.... what optional equipment became standard equipment in later years.

 

 

 

It's a distributor. Distributors require maintenance.

The problem with the optispark is that the location makes maintenance difficult, and if you're paying someone else to do the work, expensive. So most people choose to skip the maintenance and drive it until it fails.

Given how much more likely the opti is to get wet than a traditional distributor, it's arguably way more reliable than those are.

I don't think the optispark was the most brilliant engineering decision, but "the majority of everybody who owns/has owned an LT1/LT4 corvette hates it with a passion" is just silly.

The vast majority of car owners aren't on internet forums, and those who are rarely start threads to describe how their car isn't broken. Complaints are amplified.

 

As I pointed out MULTIPLE times, this has been my personal experience of Optispark nightmares from a '95 and '96. That's right, the one's with the factory miracle vent.

In the case of my '96, I did my research and bought a Petris because they've been making and selling Optispark replacements for seven years longer than yours and whalemans beloved optidoc. That failed in 16 months at the bearing, NOT the sensor. So much for the mitsubishi miracle meme.

On the '95 I went with AIP. It's still going strong for the new owner.

I am thrilled that your experience has not mirrored mine. But your experience does NOT negate mine. You just won your spin at the crap table. For now.

The sheer volume of rants about the optispark are not baseless. They permeate every LT-1 forum for a reason. Where there's smoke, you'll find fire.

I don't like to drive my '96 farther than AAA can tow it. Not if, but WHEN.

 

 

I think I have a 180 t-stat laying around for my 94 that I've never used and I have a Hypertech programmer that I believe is capable of setting the fans. Is there any particular method for choosing what temperature the fans come on with a certain t-stat?

 

Hey Diz,
My Optispark ordeal has been well documented, photographed and videotaped. There's no magic bullet here. Pretty sure you'll find a design flaw with every generation Corvette from what I've read. Warped heads on the wimpy L98. Harmonic balancers and electronics on the C5. Even the C7s have problems. The list is long and stupid. In this case, replacement options just aren't good. With or without the mitsubishi sensor.

I am all in with Park City Tom on this issue. Buy the cheapest with the best warranty. And keep your AAA card handy.

Not IF, but WHEN.

 

For the 95 and 96 Opti, be sure that the vent line is functioning. The orifice/filter tends to clog over time and disables this feature. The life span of the distributor will be affected if this happens.

 

I don't think the opti is any less reliable than standard GM HEI distributor used on the TPI cars. Replacing it is the major "complaint generator" on places like this one. I swapped out distributors over the years on many GM vehicles with rear intake mounting point, both small block & big block. It's an easy procedure for the DIYer, as is just a basic cap/rotor/wires/plugs tune up. Not so easy on a gen 2 small block.....in any car let alone a vette.

 

I have a 96. Opti was still running fine at 126k and never failed but during a recon tear down, I found the original bearing had a hell of a wiggle. I attempted to rebuild the stock one but the single shouldered bearing I bought still had a little wiggle, regardless of direction of install. If i could find the double shouldered bearing, I'd still be running the stock, rebuilt unit. I bought an AIP unit, installed the stock Mistubishi sensor, which I cleaned out with electronic parts cleaner and put it on the car. Runs fine.

 

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