What is an Opti?
Thread Starter
Intermediate
Joined: Sep 2007
Posts: 36
Likes: 0
From: Cincinnati, Ohio
What is an Opti?
I have done alot of reading on this forum searching for an answer to my "super rich" running 1988. I have came accross several mentions of the opti and I am kind of embarrasssed to admit that I don't know what that is. Anyone care to explain?
Thanks
Thanks
Team Owner
Joined: Sep 2001
Posts: 62,142
Likes: 1,729
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Its the type of distributor ignition used on LT1/4 engines. You dont have it.
It sits on front of the motor, which means if they dare wash the engine it gets wet, and that thing doesnt like getting wet. Later years have a vented one, which doesnt fail when wet.
It sits on front of the motor, which means if they dare wash the engine it gets wet, and that thing doesnt like getting wet. Later years have a vented one, which doesnt fail when wet.
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
It's understandable that someone would be confused about opti's due to all the mi-information about it, due to some owners being screwed by shops, and having it spread around as gospel. It is, as stated above merely a distributer cap and rotor with a sensor that tells the computer the position of the cam shaft, and thus the engine. It is in a bad location, so it's susceptible to water from bad water pumps and engine washings. Other than that they are AT LEAST as reliable as any other distributer. Because they are only used on LT1-4 engines, there isn't a good secondary market for them, and they cost $220-$350 new (deduct $100 if you only want the cap and rotor
). Most of the problems are actually in other parts of the system (wires,plugs, coil, ignition module, etc.), but like VATS, it's the first thing everybody blames.
). Most of the problems are actually in other parts of the system (wires,plugs, coil, ignition module, etc.), but like VATS, it's the first thing everybody blames.
Le Mans Master
Joined: May 2005
Posts: 7,340
Likes: 2,272
From: Central Maryland
Here's a re-run of a post I made here some time ago:
--------------
The Optispark is a distributor, but is rather different from any other distributor. It is mounted to the front of the timing cover, and it is mechanically coupled to the front end of the camshaft.
The Optispark is essentially a two-part device. It contains a low-voltage optical section (camshaft sensors), and a high-voltage section (distribution of spark) that uses a cap & rotor.
The optical section uses two optical sensors and a triggerwheel to determine, with great accuracy, the position, velocity, and acceleration of the camshaft. One sensor (the high-resolution sensor) reads a series of holes near the outer edge of the triggerwheel. This high-resolution sensor feeds electrical pulses to the ECM, which the ECM then uses to calculate camshaft velocity and acceleration. The other sensor (low-resolution) reads a series of eight holes nearer to the center of the triggerwheel, and it feeds electrical pulses to the ECM, which the ECM then uses to calculate camshaft position. The engine will run (although not optimally) if the high-resolution signal is absent, but it will not run if the low-resolution signal vanishes.
The ECM uses these timing pulses from the optical section of the Optispark, in combination with data from numerous other on-board sensors (Vehicle Speed Sensor, Mass Air Flow Sensor, Engine Coolant Temperature Sensor, Knock Sensor, Intake Air Temperature Sensor, Manifold Absolute Pressure Sensor, Throttle Position Sensor, etc) to exercise very tight control over spark timing. In fact, the ECM can even retard the spark on only the offending cylinder, in the event that one of the knock sensors triggers.
The high-voltage, distributor section of the Optispark functions the same as the cap and rotor of any conventional distributor, but the cap is rather different in its design. Because the plug wire towers are not spaced equidistant around the cap, and because the towers are not arranged in the same sequence as the engine’s firing order, conductive ink is used to make the connections from the contacts to the towers.
The Optispark was, conceptually, a brilliant design, but it suffered from two major flaws:
1.There were durability issues, a great many of which were associated with moisture build-up inside of the Opti. This moisture build-up could result from condensation, or from invasion of liquid from outside if the Opti got douched by coolant from a leaking water pump, hose, etc, or if the engine was cleaned with a water hose.
2.The Opti was mounted to the timing cover, behind and beneath the water pump. This placement left the unit vulnerable to coolant leaks (see 1 above), and also placed the unit where accessibility was a major issue in the event that a problem developed with the Opti.
The Optispark works extremely well, so long as everything’s in order. Problems only arise when something goes wrong with the unit, and it can become a major headache mostly because of the relative inaccessibility of the unit because of its placement on the front of the engine. Digging down to gain access to the Opti requires removal of the water pump, etc.
The Opti was used on the Corvette LT1 engines from ’92 – ’96, and on the LT4 engine (which only was used on manual transmission Corvettes in ’96). GM revised the design of the Opti mid-way through its life. The first-generation Opti was used on ’92 – ’94 Corvettes, and the revised, second-generation Opti was used on ’95 and ’96 Corvettes. The first-gen Opti was passively vented with three weep holes to allow moisture to drain out of the unit. This proved inadequate, and the revised, second-gen Opti was actively vented using intake manifold vacuum to draw filtered air through the Opti’s housing. The second-gen Opti was a major improvement over the first-gen units.
There are several aftermarket products available which attempt to address the Opti problems:
1.The DynaSpark is a direct, bolt-on replacement for the entire Optispark unit. It is a very well-engineered and well-manufactured item, and is also actively vented. It sells for approximately $600.
2. MSD is now also selling a direct, bolt-on replacement for the Opti. This unit is new to the market, so there isn't a lot of field history available to suggest how well it holds up.
3.The Delteq system is a DIS conversion package that eliminates the high-voltage section of the Opti. It uses four Cadillac Northstar wastespark coilpacks to deliver spark to the eight spark plugs. This system is carried on a bracket that mounts on the driver’s side valve cover of the LT1/LT4 engine. It requires the use of different-length plug wires, and on some Corvettes also requires either the elimination of the tachometer filter, or the addition of a MSD tach amplifier, in order to preserve the operation of the factory tachometer. It’s important to note that the Delteq system does not eliminate the optical section of the Optispark. The ECM will still require the camshaft data from the Opti to drive the Delteq system. The Delteq also adds some clutter and a non-stock appearance to the engine bay.
4.The LTCC system is similar conceptually to the Delteq, and accomplishes basically the same things, but it uses eight LS1-style coilpacks, rather than the four Northstar wastespark coilpacks that the Delteq uses.
I installed a DynaSpark on my ’94 in August 2004, and I’m very pleased with it. The car runs great, and I no longer have any anxieties about Opti issues.
The issues surrounding the Optispark should be understood by those who own, or are considering purchasing, a car that uses the Opti. So long as they are understood, there’s no reason to be scared away from owning and enjoying these great, LT1 or LT4 Corvettes.
I hope this helps to remove some of the mystery about the OptiSpark.
Be well,
SJW
--------------
The Optispark is a distributor, but is rather different from any other distributor. It is mounted to the front of the timing cover, and it is mechanically coupled to the front end of the camshaft.
The Optispark is essentially a two-part device. It contains a low-voltage optical section (camshaft sensors), and a high-voltage section (distribution of spark) that uses a cap & rotor.
The optical section uses two optical sensors and a triggerwheel to determine, with great accuracy, the position, velocity, and acceleration of the camshaft. One sensor (the high-resolution sensor) reads a series of holes near the outer edge of the triggerwheel. This high-resolution sensor feeds electrical pulses to the ECM, which the ECM then uses to calculate camshaft velocity and acceleration. The other sensor (low-resolution) reads a series of eight holes nearer to the center of the triggerwheel, and it feeds electrical pulses to the ECM, which the ECM then uses to calculate camshaft position. The engine will run (although not optimally) if the high-resolution signal is absent, but it will not run if the low-resolution signal vanishes.
The ECM uses these timing pulses from the optical section of the Optispark, in combination with data from numerous other on-board sensors (Vehicle Speed Sensor, Mass Air Flow Sensor, Engine Coolant Temperature Sensor, Knock Sensor, Intake Air Temperature Sensor, Manifold Absolute Pressure Sensor, Throttle Position Sensor, etc) to exercise very tight control over spark timing. In fact, the ECM can even retard the spark on only the offending cylinder, in the event that one of the knock sensors triggers.
The high-voltage, distributor section of the Optispark functions the same as the cap and rotor of any conventional distributor, but the cap is rather different in its design. Because the plug wire towers are not spaced equidistant around the cap, and because the towers are not arranged in the same sequence as the engine’s firing order, conductive ink is used to make the connections from the contacts to the towers.
The Optispark was, conceptually, a brilliant design, but it suffered from two major flaws:
1.There were durability issues, a great many of which were associated with moisture build-up inside of the Opti. This moisture build-up could result from condensation, or from invasion of liquid from outside if the Opti got douched by coolant from a leaking water pump, hose, etc, or if the engine was cleaned with a water hose.
2.The Opti was mounted to the timing cover, behind and beneath the water pump. This placement left the unit vulnerable to coolant leaks (see 1 above), and also placed the unit where accessibility was a major issue in the event that a problem developed with the Opti.
The Optispark works extremely well, so long as everything’s in order. Problems only arise when something goes wrong with the unit, and it can become a major headache mostly because of the relative inaccessibility of the unit because of its placement on the front of the engine. Digging down to gain access to the Opti requires removal of the water pump, etc.
The Opti was used on the Corvette LT1 engines from ’92 – ’96, and on the LT4 engine (which only was used on manual transmission Corvettes in ’96). GM revised the design of the Opti mid-way through its life. The first-generation Opti was used on ’92 – ’94 Corvettes, and the revised, second-generation Opti was used on ’95 and ’96 Corvettes. The first-gen Opti was passively vented with three weep holes to allow moisture to drain out of the unit. This proved inadequate, and the revised, second-gen Opti was actively vented using intake manifold vacuum to draw filtered air through the Opti’s housing. The second-gen Opti was a major improvement over the first-gen units.
There are several aftermarket products available which attempt to address the Opti problems:
1.The DynaSpark is a direct, bolt-on replacement for the entire Optispark unit. It is a very well-engineered and well-manufactured item, and is also actively vented. It sells for approximately $600.
2. MSD is now also selling a direct, bolt-on replacement for the Opti. This unit is new to the market, so there isn't a lot of field history available to suggest how well it holds up.
3.The Delteq system is a DIS conversion package that eliminates the high-voltage section of the Opti. It uses four Cadillac Northstar wastespark coilpacks to deliver spark to the eight spark plugs. This system is carried on a bracket that mounts on the driver’s side valve cover of the LT1/LT4 engine. It requires the use of different-length plug wires, and on some Corvettes also requires either the elimination of the tachometer filter, or the addition of a MSD tach amplifier, in order to preserve the operation of the factory tachometer. It’s important to note that the Delteq system does not eliminate the optical section of the Optispark. The ECM will still require the camshaft data from the Opti to drive the Delteq system. The Delteq also adds some clutter and a non-stock appearance to the engine bay.
4.The LTCC system is similar conceptually to the Delteq, and accomplishes basically the same things, but it uses eight LS1-style coilpacks, rather than the four Northstar wastespark coilpacks that the Delteq uses.
I installed a DynaSpark on my ’94 in August 2004, and I’m very pleased with it. The car runs great, and I no longer have any anxieties about Opti issues.
The issues surrounding the Optispark should be understood by those who own, or are considering purchasing, a car that uses the Opti. So long as they are understood, there’s no reason to be scared away from owning and enjoying these great, LT1 or LT4 Corvettes.
I hope this helps to remove some of the mystery about the OptiSpark.
Be well,
SJW
