LT1 Spark Plug Change
Thread Starter
Joined: Apr 2007
Posts: 2
LT1 Spark Plug Change
Hi all,
I just bought my first Vette in January and would like to throw a tune up on it. Is there any tricks to changing the spark plugs? Also I can't even see the distributor. Would I be better off having a shop change the cap and rotor? I do have an average mechanical ability. 1996 LT1 Auto.
Thanks in advance for all the help. These forums are invaluable.
I just bought my first Vette in January and would like to throw a tune up on it. Is there any tricks to changing the spark plugs? Also I can't even see the distributor. Would I be better off having a shop change the cap and rotor? I do have an average mechanical ability. 1996 LT1 Auto.
Thanks in advance for all the help. These forums are invaluable.
Joined: Nov 2006
Posts: 209
From: Panama City Florida
RE: LT1 Spark Plug Change
HI on your 96 the dist is below the water pump i replaced mine took about 3 hours to change dist the plugs were a son of gun to change skuffed up my arms pretty good if you have someone that will do it for a reasable price let them
Senior Member
Joined: Mar 2006
Posts: 643
From:
RE: LT1 Spark Plug Change
http://forums.corvetteforum.com/showthread.php?t=956100
OptiSpark
History
The OptiSpark (Opti) was introduced in 1991, with the LT1 as part of the 1992 model year. Why did they do the Opti? Even Gordon Killebrew doesn't have a clue.
The Opti is made up of two sides, one side, the side against the engine, is an optical pickup. The pickup is made by Mitsubishi, and is a very reliable component. The optical system reads a disc that has marks in it. On the outer edge are 360 marks, inside that, are four marks. The outer marks create the so called "High Resolution" signal to control timing, the inner marks, or "Low Resolution" are used to signal fuel delivery.
A common shaft joins the optical side with the high voltage side. The high voltage side is similar to any distributor, except it is much thinner. The unique part, the sides of the cap are sequenced, so all the odds are on one side, evens on the other!
In 1995, the second generation of the Opti was released. It has a venting hose and is better constructed.
Problems
Codes can present themselves if an Opti is failing. These codes very by year, but for the earlier versions, codes 16 and 36 are bad(Note: these codes only apply to 1992 - 1995, 1996 uses ODBII and has different codes). This means the optical portion has a problem. Most likely, the error is caused not so much a failure in the optical portion, but the bearings having worn out, causing a wobble in the drive shaft.
A common problem is when coolant from a bad waterpump leaks in. Coolant will eat the grease inside the sealed bearings. This causes the common shaft to wobble.
If there is a wondering idle or a high RPM miss, you can blame a bad cap/rotor. The cap/rotor fails due to carbon tracing, caused by moisture getting into the Opti.
Factory Options
New Optis are available from the dealer. Also available is the Venting Hose Kit, that can be retrofitted to the original cap design.
You can also update an earlier engine to the later Opti, by changing the timing cover and various internal parts related to the timing gear.
I cannot advise a cap/rotor change. The labour is the same... and there is no guarentee that a rotor change will result in a long term repair.
If your car is a 1995 or newer, then a cap/rotor change might just be worth investigating.
Regardless of the vintage, removing the cap and sealing with RTV is a good idea. It might not be a bad idea to install a drain hose on the waterpump, to direct the weap holes output to the side, instead of on the Opti.
I do not recommend the Ecklers or Mid-America cap venting system. It is a single hose, and as such does not create positive pressure. It might suck some stuff out, but I just don't see how it can without creating a complete loop.
Aftermarket Options
There are now a few options available:
[ul][*]Dyna-Tech - This is a totally reengineered version of the Opti. A good idea for those who wish to maintain a stock look.[/ul]
[ul][*]LTCC - This uses eight LS1 coils, and the Opti to read the data needed to fire the coils.[/ul]
[ul][*]DelTeq - This is similar to the LTCC, but uses a Northstar coil pack.[*]
Generic replacement Optis are not recommended. They don't include the cap/rotor and are of questionable reliability. [/ul]
It is important to understand that the LT1 still needed the harmonic balancer (essentially the crank pulley) to be balanced and "keyed" to the right place on the crank. If you ever remove the harmonic balancer, mark the location on the crank CORRECTLY or it will be a problem. Sadly, the crank is not keyed, this means the pulley can go on anyway it wants to.
Before you condemn the Opti, make sure the coil, ignition module and coil wire are in good shape.
OptiSpark
History
The OptiSpark (Opti) was introduced in 1991, with the LT1 as part of the 1992 model year. Why did they do the Opti? Even Gordon Killebrew doesn't have a clue.
The Opti is made up of two sides, one side, the side against the engine, is an optical pickup. The pickup is made by Mitsubishi, and is a very reliable component. The optical system reads a disc that has marks in it. On the outer edge are 360 marks, inside that, are four marks. The outer marks create the so called "High Resolution" signal to control timing, the inner marks, or "Low Resolution" are used to signal fuel delivery.
A common shaft joins the optical side with the high voltage side. The high voltage side is similar to any distributor, except it is much thinner. The unique part, the sides of the cap are sequenced, so all the odds are on one side, evens on the other!
In 1995, the second generation of the Opti was released. It has a venting hose and is better constructed.
Problems
Codes can present themselves if an Opti is failing. These codes very by year, but for the earlier versions, codes 16 and 36 are bad(Note: these codes only apply to 1992 - 1995, 1996 uses ODBII and has different codes). This means the optical portion has a problem. Most likely, the error is caused not so much a failure in the optical portion, but the bearings having worn out, causing a wobble in the drive shaft.
A common problem is when coolant from a bad waterpump leaks in. Coolant will eat the grease inside the sealed bearings. This causes the common shaft to wobble.
If there is a wondering idle or a high RPM miss, you can blame a bad cap/rotor. The cap/rotor fails due to carbon tracing, caused by moisture getting into the Opti.
Factory Options
New Optis are available from the dealer. Also available is the Venting Hose Kit, that can be retrofitted to the original cap design.
You can also update an earlier engine to the later Opti, by changing the timing cover and various internal parts related to the timing gear.
I cannot advise a cap/rotor change. The labour is the same... and there is no guarentee that a rotor change will result in a long term repair.
If your car is a 1995 or newer, then a cap/rotor change might just be worth investigating.
Regardless of the vintage, removing the cap and sealing with RTV is a good idea. It might not be a bad idea to install a drain hose on the waterpump, to direct the weap holes output to the side, instead of on the Opti.
I do not recommend the Ecklers or Mid-America cap venting system. It is a single hose, and as such does not create positive pressure. It might suck some stuff out, but I just don't see how it can without creating a complete loop.
Aftermarket Options
There are now a few options available:
[ul][*]Dyna-Tech - This is a totally reengineered version of the Opti. A good idea for those who wish to maintain a stock look.[/ul]
[ul][*]LTCC - This uses eight LS1 coils, and the Opti to read the data needed to fire the coils.[/ul]
[ul][*]DelTeq - This is similar to the LTCC, but uses a Northstar coil pack.[*]
Generic replacement Optis are not recommended. They don't include the cap/rotor and are of questionable reliability. [/ul]
It is important to understand that the LT1 still needed the harmonic balancer (essentially the crank pulley) to be balanced and "keyed" to the right place on the crank. If you ever remove the harmonic balancer, mark the location on the crank CORRECTLY or it will be a problem. Sadly, the crank is not keyed, this means the pulley can go on anyway it wants to.
Before you condemn the Opti, make sure the coil, ignition module and coil wire are in good shape.
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