LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Best Opti????

Old 02-11-2019, 08:01 AM
  #16  
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Re: Best Opti????

I got pretty lucky,I think. A local dealer had a brand new GM Opti, in the box covered with dust on his shelf. He was glad to finally get rid of it and gave us a good deal on it. It’s a vented one so we replaced the original line with new line and sealed everything up. New water pump too.

this is on my 94 Buick Estate Wagon.
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Old 02-11-2019, 08:31 AM
  #17  
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Re: Best Opti????

Wasn't Delphi actually part of GM until it was spun off? I always considered their stuff to be OEM even if it wasn't branded ACDelco. Regardless, it seems they haven't been manufacturing optis for a few years now. I don't think I ever saw a remanufactured Delphi, unless they were doing them for ACDelco.

I bought a couple of spare ACDelco/GMPP units several years when Summit was clearing them out. I guess I'm glad that I did.

Last edited by BTC; 02-11-2019 at 08:34 AM.
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Old 02-13-2019, 08:00 PM
  #18  
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Re: Best Opti????

Bentwings BTC If ever your optispark goes bad, for whatever reason, there is a guy on ebay who refurbishes only genuine OEM optisparks with the Mitsubishi sensors. He goes by the name berrington1.
https://www.ebay.com/itm/Optispark-reconditioning-service-with-data-that-it-works/322692854278?epid=2211552581&hash=item4b21fe3206:g :Tj0AAOSwVm5ZARQg:rk:1f:0#rwid

I figure it is a way to help preserve your OEM optispark if the sensor is not what failed on it and it helps small-time business people who can contribute to the classic car industry and keep our cars running well beyond their expected lifetime. I certainly will fight to keep my LT1 bird going strong into the coming decades, so long as the New Green Deal doesn't force me to part with her...
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Old 02-16-2019, 10:43 AM
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Re: Best Opti????

Phoenix and all,

I like what Berrington1 is doing with his rebuilds as well (though I do not have one on my car). He claims to be a 20 year veteran test engineer and given his test bench photo and what he is testing I don't doubt his claim.

He is heating the unit while it is on the scope which may be very important. I used to work in a semi-conductor reliability department and we saw a lot of returns and problems with devices that tested good at room temp but then failed at elevated temperatures; usually due to stresses induced by different rates of expansion in the device packaging or the printed circuit board material. Berrington claims to be bringing the opti up to 180F operating temperature and is verifying that the outputs are not degrading at temperature.

He also claims to be seal testing the units which (if true and done correctly) is a big difference from the less expensive new unit sold at Summit (the last time I bought one anyway). The Summit unit did not have a sealed rotation input bearing and would not give me any vacuum reading when I pumped it with my mini mighty vac tool.

Last edited by squarehead; 02-16-2019 at 04:18 PM. Reason: spelling
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Old 02-16-2019, 11:02 AM
  #20  
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Re: Best Opti????

I should find my factory opti and send it to him for a rebuild. I don't know what I did with it when I replaced it, but I don't believe I would have thrown it away. The one I replaced it with is supposedly an ACDelco that I bought off of someone on this site many years ago. It's got about 500 miles on it and I bought a couple from Summit Racing back when they were clearing them out in 2012-2013. I don't think I need another opti, but I guess you can never have too many.
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Old 02-16-2019, 12:04 PM
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Re: Best Opti????

Originally Posted by BTC View Post

I don't think I need another opti, but I guess you can never have too many.
LOL!

I think that Berrington1 pays a bounty on old original Delco units so it might be worth your trouble make the search.
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Old 02-16-2019, 01:36 PM
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Re: Best Opti????

45 year electrical test engineer here. A photo of my Opti test setup in 2015. The Opti is mounted in the plywood box. A DC motor is used to spin it at varying speed: A 150 watt incandescent light bulb is used for temperature setting and a temperature control keeps the temp at a preset level.The supply current and waveforms are monitored continuously. A PC is attached and will log the time of loss of either Hi or Low res signal, or dc supply current.


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Old 02-16-2019, 04:17 PM
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Re: Best Opti????

Hi GaryDoug,

Have you checked out what Berrington1 is doing with the opti rebuilds on eBay? What do you think?

The photo of his test rig will look familiar to you!
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Old 02-16-2019, 05:53 PM
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Re: Best Opti????

He is about 4 years behind me ;-) See this one in 2014 with a hair dryer:
And this post #10 in this topic in 2015 using a portable heater:
https://www.camaroz28.com/forums/lt1...talled-877594/

In both cases I found the heat soak to be inadequate unless the Opti was placed in a chamber. Otherwise the heat did not soak evenly. I purchased one very cheap Opti on eBay just for evaluation and it has held up so far to this type of bench test, but I would never use it in a real engine as that environment is far more stressful. In other worlds I don't think his test is enough. Nor is mine.

But I normally do not repair these. I have done only 5 so far just for friends. Only with one was I not able to repair it, and it was a real OEM version with a bad amplifier board. The amplifier board is hidden under the the metal plate opposite the optic sensor.




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Old 02-16-2019, 09:09 PM
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Re: Best Opti????

Thx for posting.
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Old 02-16-2019, 10:20 PM
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Re: Best Opti????

Too bad my original got trashed before I knew about the rebuilds possible. I think I’ll hit the U Pull in the spring after the snow goes away and see if I can find another OEM unit to get rebuilt just in case. I’d really like the new one to go a 100k. The car will probably be done in by then.

I really should also look for another wagon. Buy it and store it. That way I’ll have a car until they take my keys.LOL
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Old 02-17-2019, 08:11 PM
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Re: Best Opti????

Jegs still has em in their magazine.
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Old 02-17-2019, 09:23 PM
  #28  
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Re: Best Opti????

I don't think Jegs is selling OEM optis. They're certainly not listed on their website. They do show some ACDelco and Delphi Cap & Rotor kits and the prices seen pretty high.
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Old 02-18-2019, 10:18 AM
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Re: Best Opti????

It reads like buying an Opti is a gamble on what went inside it no matter the manufacturer. Difficult to test and difficult to replace it's very frustrating in the age of smart phones and modern digital controls. I bought a "rugged" smart phone for only a hundred bucks and I can drop it 10 feet or submerge it 10 feet under water and it will still work. Takes great pictures too. But the opti still uses 25 year old electronics that are vunerable to water, heat and possibly vibration. If only a large tech company like Samsung or LG would re-engineer it for us - but we know that won't happen.
So we are stuck with a sensor/detector to produce a high and low resolution signal to work with the stock computer. And that's where the hobbiest gives up rather than try and convert to a 28x or 54x system. I know I don't want to take that on. Heck I might be driving an electric car before I could finish that much of a project. Or maybe the electric car would be driving me I should say.
And it makes me wonder why the water pump is timing gear driven. I don't know of any cars since the Opti that use the timing gear through a shaft to drive the pump. So they left the water pump close enough to block the Opti removal and leak on the opti too making a troublesome part much worse.
Aftermarket companies just haven't been able to find any fixes probably because the enginneering effort involved.

On the other hand some owners are able to swap their opti in 2 hours I have read so even a primative fix it seems to be the most practical fix. The fear of get stranded on a long trip remains. But heck that pretty much goes for any 25 year old car take it or leave it. Just my 2 cents here.
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Old 02-18-2019, 11:47 AM
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Re: Best Opti????

Originally Posted by cardo0 View Post
It reads like buying an Opti is a gamble on what went inside it no matter the manufacturer. Difficult to test and difficult to replace it's very frustrating in the age of smart phones and modern digital controls. I bought a "rugged" smart phone for only a hundred bucks and I can drop it 10 feet or submerge it 10 feet under water and it will still work. Takes great pictures too. But the opti still uses 25 year old electronics that are vunerable to water, heat and possibly vibration. If only a large tech company like Samsung or LG would re-engineer it for us - but we know that won't happen.
So we are stuck with a sensor/detector to produce a high and low resolution signal to work with the stock computer.
I know how you feel. The obvious issue here is that the Optispark technology was merely a small stepping stone for the ignition system set-up that the LS family would eventually receive. I am sure GM engineers took the time to gain any last minute R&D information they could get from the Optispark before coming up with the direct ignition multi-coil pack system. It's no different with the intake manifold of the LT1, the TPI is actually the prototype for what would become the LS family intake system, granted GM engineers would also have bridged the gap learning what they could from the LT1 intake and blending the best of both into the LS intake.


Originally Posted by cardo0 View Post
Aftermarket companies just haven't been able to find any fixes probably because the enginneering effort involved.
The problem with the optispark and why the aftermarket won't bother to create a truly sealed and reliable unit is that people have been quick to ditch these ignition systems for the LS1 PCM 24xx systems. People are ditching their LT1s and swapping in LS family engines into their former LT1 f-bodies/b-bodies and Corvettes. There is not enough of a market to justify making such a product for the expenses required for R&D and then the money needed for the molds. You would go bankrupt trying to sell enough of them to break even.

For me, I am actually torn about swapping over to the LS1 PCM torque head ignition system when my Petris optispark is working just fine! It would actually save me money to stick with the optispark for my future engine build if the Petris is still running strong by then and the engine builder can tune my LT1 PCM for it, however he may have to use an aftermarket computer.


Originally Posted by cardo0 View Post
And it makes me wonder why the water pump is timing gear driven.
Less parasitic drain on the engine. This is one aspect of the 5.7L LT1 design that I like, and the next best thing when compared to using an electric pump conversion! Instead of the traditional water pump that is accessory belt driven and which adds more tug to the belt, the LT1 uses the actual cam itself to spin the impeller so in theory less energy is required to turn the water pump impeller directly when connected by gear to the cam versus using a water pump pulley attached to the impeller which adds resistance to the entire accessory belt run off the crank.

Last edited by Phoenix'97; 02-18-2019 at 11:59 AM.
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