I need any info about optispark system please.
Team Owner
Joined: Oct 2000
Posts: 96,443
Likes: 9
From: Fort Knox, KY
Cruise-In IV Veteran
Cruise-In VI Veteran
Cruise-In VII Veteran
Cruise-In VIII Veteran
Instructor
Joined: Mar 2005
Posts: 174
Likes: 3
From: Yorba Linda CA
Hi Damien-
The first thing that came to mind when I read your post is that I believe the optispark first began on the 1991 model. Since your profile says you have an 1989 I thought I'd better mention this so that there wasn't a confusion and we started giving you wrong advice.
You might want to look at the first "sticky" at the top of this page -"C4 Technical Summary and FAQ - Please Read on a Regular Basis" Scroll down the page a bit. There is a section on the optispark.
Best regards from sunny California!
The first thing that came to mind when I read your post is that I believe the optispark first began on the 1991 model. Since your profile says you have an 1989 I thought I'd better mention this so that there wasn't a confusion and we started giving you wrong advice.
You might want to look at the first "sticky" at the top of this page -"C4 Technical Summary and FAQ - Please Read on a Regular Basis" Scroll down the page a bit. There is a section on the optispark.
Best regards from sunny California!
Pro
Joined: Jan 2004
Posts: 653
Likes: 0
From: Northern New Jersey
St. Jude Donor '03-'05-'06-'07-'08
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Actually it was '92 on the Corvette. The improved opti came along in '95 in the Vette and the F-bodies but actually came out a year sooner on the Impalas and other full-sized GM cars in which the LT1 was used.
Le Mans Master
Joined: May 2005
Posts: 7,362
Likes: 2,282
From: Central Maryland
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.
If you have a good set of general mechanic's tools, and decent mechanical skills, you can tackle an Opti swap yourself. No special tools are required. Here are a few tech tips I wrote up some time ago about doing an Opti swap:
Get a Factory Service Manual, and follow the procedure it lays out.
A few tips (I'm going from memory here, so I'll probably forget a few things):
Drain the cooling system.
Disconnect the MAF sensor and IAT sensor and remove the air intake duct with the MAF and IAT as an assembly.
Disconnect the ECT sensor and remove it from the water pump.
Remove the serpentine belt and tensioner.
You may find that you’ll need to unbolt the coil/ICM bracket from the front of the right cylinder head. I can’t recall for sure whether or not I did.
Unbolt (but don't remove) the power steering pump. This will help you to sneak the new plug wires in/out behind the pump, but may also be somewhat helpful when working on the water pump/Opti.
If you want more room to work, you can remove the radiator, but it isn't strictly necessary, and it involves considerably more work to remove it (I left mine in place).
The FSM will tell you that you need a special Kent-Moore puller to remove the crank pulley/damper. You don't. Here's how to get it off:
1. Raise the front of the vehicle enough that you can get under the car (it's also helpful to have it at a more comfortable height while you're working from above).
2. Remove the three bolts that secure the pulley/damper to the hub.
3. Mark the damper and hub so that you can easily see how to realign them to each other later.
4. Slide under the car with a long pry bar or hardwood dowel (I use a jumbo Snap-On screwdriver that's around two feet long) and a mallet.
5. Place the tip of the pry bar against the rear face of the damper, as close to the hub as possible (Ideally rest the tip alongside of the hub).
6 Give the pry bar a few whacks with the mallet, and with any luck the damper will pop off without too much of a fight.
You may find it helpful to apply a few whacks, then rotate the crankshaft in 120* increments, whacking it a few times at each interval (I haven't needed to do this).
It's also helpful to, if possible, shoot a bit of penetrating oil where the damper meets the hub, a day or more in advance of doing the job.
After you get the damper off, clean the damper/hub mating surfaces to remove all corrosion, etc, and apply a very thin coating of anti-sieze compound to these surfaces before you reassmble the damper to the hub. This should make it a lot easier to get the damper off next time.
Once the damper is removed, rotate the crankshaft so that one wing of the damper hub is at the six-o'clock position. This will position the other two wings at around the ten- and two-o'clock positions. In this orientation, the Opti will clear the hub as it is being removed/installed.
The Opti basically unbolts and pulls off as you'd expect, once you have the water pump and damper out of the way.
Once the Opti is out of the way, inspect the shaft seals for the Opti, water pump, and crankshaft. If they show any signs of leakage, replace them now.
When you install the new Opti, be sure to align it correctly with the cam gear, and don't force it into place against the timing cover (do NOT use the bolts to draw it into place). At most, give it a gentle bump with the heel of your hand to encourage it to pop into place.
Reassemble everything else.
Follow the cooling system refill procedure in the FSM carefully, and you'll have no problems with this. In particular, be sure to bleed the air out of the system as it's being refilled. I recommend a re-bleed after each of the first three thermal cycles.
Does this help?
Be well,
SJW
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.
If you have a good set of general mechanic's tools, and decent mechanical skills, you can tackle an Opti swap yourself. No special tools are required. Here are a few tech tips I wrote up some time ago about doing an Opti swap:
Get a Factory Service Manual, and follow the procedure it lays out.
A few tips (I'm going from memory here, so I'll probably forget a few things):
Drain the cooling system.
Disconnect the MAF sensor and IAT sensor and remove the air intake duct with the MAF and IAT as an assembly.
Disconnect the ECT sensor and remove it from the water pump.
Remove the serpentine belt and tensioner.
You may find that you’ll need to unbolt the coil/ICM bracket from the front of the right cylinder head. I can’t recall for sure whether or not I did.
Unbolt (but don't remove) the power steering pump. This will help you to sneak the new plug wires in/out behind the pump, but may also be somewhat helpful when working on the water pump/Opti.
If you want more room to work, you can remove the radiator, but it isn't strictly necessary, and it involves considerably more work to remove it (I left mine in place).
The FSM will tell you that you need a special Kent-Moore puller to remove the crank pulley/damper. You don't. Here's how to get it off:
1. Raise the front of the vehicle enough that you can get under the car (it's also helpful to have it at a more comfortable height while you're working from above).
2. Remove the three bolts that secure the pulley/damper to the hub.
3. Mark the damper and hub so that you can easily see how to realign them to each other later.
4. Slide under the car with a long pry bar or hardwood dowel (I use a jumbo Snap-On screwdriver that's around two feet long) and a mallet.
5. Place the tip of the pry bar against the rear face of the damper, as close to the hub as possible (Ideally rest the tip alongside of the hub).
6 Give the pry bar a few whacks with the mallet, and with any luck the damper will pop off without too much of a fight.
You may find it helpful to apply a few whacks, then rotate the crankshaft in 120* increments, whacking it a few times at each interval (I haven't needed to do this).
It's also helpful to, if possible, shoot a bit of penetrating oil where the damper meets the hub, a day or more in advance of doing the job.
After you get the damper off, clean the damper/hub mating surfaces to remove all corrosion, etc, and apply a very thin coating of anti-sieze compound to these surfaces before you reassmble the damper to the hub. This should make it a lot easier to get the damper off next time.
Once the damper is removed, rotate the crankshaft so that one wing of the damper hub is at the six-o'clock position. This will position the other two wings at around the ten- and two-o'clock positions. In this orientation, the Opti will clear the hub as it is being removed/installed.
The Opti basically unbolts and pulls off as you'd expect, once you have the water pump and damper out of the way.
Once the Opti is out of the way, inspect the shaft seals for the Opti, water pump, and crankshaft. If they show any signs of leakage, replace them now.
When you install the new Opti, be sure to align it correctly with the cam gear, and don't force it into place against the timing cover (do NOT use the bolts to draw it into place). At most, give it a gentle bump with the heel of your hand to encourage it to pop into place.
Reassemble everything else.
Follow the cooling system refill procedure in the FSM carefully, and you'll have no problems with this. In particular, be sure to bleed the air out of the system as it's being refilled. I recommend a re-bleed after each of the first three thermal cycles.
Does this help?
Be well,
SJW
Drifting
Joined: Aug 2004
Posts: 1,430
Likes: 2
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.
If you have a good set of general mechanic's tools, and decent mechanical skills, you can tackle an Opti swap yourself. No special tools are required. Here are a few tech tips I wrote up some time ago about doing an Opti swap:
Get a Factory Service Manual, and follow the procedure it lays out.
A few tips (I'm going from memory here, so I'll probably forget a few things):
Drain the cooling system.
Disconnect the MAF sensor and IAT sensor and remove the air intake duct with the MAF and IAT as an assembly.
Disconnect the ECT sensor and remove it from the water pump.
Remove the serpentine belt and tensioner.
You may find that you’ll need to unbolt the coil/ICM bracket from the front of the right cylinder head. I can’t recall for sure whether or not I did.
Unbolt (but don't remove) the power steering pump. This will help you to sneak the new plug wires in/out behind the pump, but may also be somewhat helpful when working on the water pump/Opti.
If you want more room to work, you can remove the radiator, but it isn't strictly necessary, and it involves considerably more work to remove it (I left mine in place).
The FSM will tell you that you need a special Kent-Moore puller to remove the crank pulley/damper. You don't. Here's how to get it off:
1. Raise the front of the vehicle enough that you can get under the car (it's also helpful to have it at a more comfortable height while you're working from above).
2. Remove the three bolts that secure the pulley/damper to the hub.
3. Mark the damper and hub so that you can easily see how to realign them to each other later.
4. Slide under the car with a long pry bar or hardwood dowel (I use a jumbo Snap-On screwdriver that's around two feet long) and a mallet.
5. Place the tip of the pry bar against the rear face of the damper, as close to the hub as possible (Ideally rest the tip alongside of the hub).
6 Give the pry bar a few whacks with the mallet, and with any luck the damper will pop off without too much of a fight.
You may find it helpful to apply a few whacks, then rotate the crankshaft in 120* increments, whacking it a few times at each interval (I haven't needed to do this).
It's also helpful to, if possible, shoot a bit of penetrating oil where the damper meets the hub, a day or more in advance of doing the job.
After you get the damper off, clean the damper/hub mating surfaces to remove all corrosion, etc, and apply a very thin coating of anti-sieze compound to these surfaces before you reassmble the damper to the hub. This should make it a lot easier to get the damper off next time.
Once the damper is removed, rotate the crankshaft so that one wing of the damper hub is at the six-o'clock position. This will position the other two wings at around the ten- and two-o'clock positions. In this orientation, the Opti will clear the hub as it is being removed/installed.
The Opti basically unbolts and pulls off as you'd expect, once you have the water pump and damper out of the way.
Once the Opti is out of the way, inspect the shaft seals for the Opti, water pump, and crankshaft. If they show any signs of leakage, replace them now.
When you install the new Opti, be sure to align it correctly with the cam gear, and don't force it into place against the timing cover (do NOT use the bolts to draw it into place). At most, give it a gentle bump with the heel of your hand to encourage it to pop into place.
Reassemble everything else.
Follow the cooling system refill procedure in the FSM carefully, and you'll have no problems with this. In particular, be sure to bleed the air out of the system as it's being refilled. I recommend a re-bleed after each of the first three thermal cycles.
Does this help?
Be well,
SJW
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.
If you have a good set of general mechanic's tools, and decent mechanical skills, you can tackle an Opti swap yourself. No special tools are required. Here are a few tech tips I wrote up some time ago about doing an Opti swap:
Get a Factory Service Manual, and follow the procedure it lays out.
A few tips (I'm going from memory here, so I'll probably forget a few things):
Drain the cooling system.
Disconnect the MAF sensor and IAT sensor and remove the air intake duct with the MAF and IAT as an assembly.
Disconnect the ECT sensor and remove it from the water pump.
Remove the serpentine belt and tensioner.
You may find that you’ll need to unbolt the coil/ICM bracket from the front of the right cylinder head. I can’t recall for sure whether or not I did.
Unbolt (but don't remove) the power steering pump. This will help you to sneak the new plug wires in/out behind the pump, but may also be somewhat helpful when working on the water pump/Opti.
If you want more room to work, you can remove the radiator, but it isn't strictly necessary, and it involves considerably more work to remove it (I left mine in place).
The FSM will tell you that you need a special Kent-Moore puller to remove the crank pulley/damper. You don't. Here's how to get it off:
1. Raise the front of the vehicle enough that you can get under the car (it's also helpful to have it at a more comfortable height while you're working from above).
2. Remove the three bolts that secure the pulley/damper to the hub.
3. Mark the damper and hub so that you can easily see how to realign them to each other later.
4. Slide under the car with a long pry bar or hardwood dowel (I use a jumbo Snap-On screwdriver that's around two feet long) and a mallet.
5. Place the tip of the pry bar against the rear face of the damper, as close to the hub as possible (Ideally rest the tip alongside of the hub).
6 Give the pry bar a few whacks with the mallet, and with any luck the damper will pop off without too much of a fight.
You may find it helpful to apply a few whacks, then rotate the crankshaft in 120* increments, whacking it a few times at each interval (I haven't needed to do this).
It's also helpful to, if possible, shoot a bit of penetrating oil where the damper meets the hub, a day or more in advance of doing the job.
After you get the damper off, clean the damper/hub mating surfaces to remove all corrosion, etc, and apply a very thin coating of anti-sieze compound to these surfaces before you reassmble the damper to the hub. This should make it a lot easier to get the damper off next time.
Once the damper is removed, rotate the crankshaft so that one wing of the damper hub is at the six-o'clock position. This will position the other two wings at around the ten- and two-o'clock positions. In this orientation, the Opti will clear the hub as it is being removed/installed.
The Opti basically unbolts and pulls off as you'd expect, once you have the water pump and damper out of the way.
Once the Opti is out of the way, inspect the shaft seals for the Opti, water pump, and crankshaft. If they show any signs of leakage, replace them now.
When you install the new Opti, be sure to align it correctly with the cam gear, and don't force it into place against the timing cover (do NOT use the bolts to draw it into place). At most, give it a gentle bump with the heel of your hand to encourage it to pop into place.
Reassemble everything else.
Follow the cooling system refill procedure in the FSM carefully, and you'll have no problems with this. In particular, be sure to bleed the air out of the system as it's being refilled. I recommend a re-bleed after each of the first three thermal cycles.
Does this help?
Be well,
SJW
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
I started this thread a year ago, still great reading: Most everything you ever wanted to know about the Opti... And were afraid to ask.
Thread Starter
Racer
Joined: Jul 2002
Posts: 466
Likes: 0
WoW guys! You provided me with loads of info. I need the info because of a debate i have at the auto school which i'm going.
Thanks a lot to all of you!
I really can say that people like all of you make this forum feel like home, i browse on other forums but their isn't a better community than this one!
Thanks a lot to all of you!
I really can say that people like all of you make this forum feel like home, i browse on other forums but their isn't a better community than this one!
