Optic spark distributor concerns

[dave69]

Just getting ready to install a 96 LT4 in my 69 c10 heard a little about this dist I have always had HEI so this is new to me what are the pros and cons? Can I just leave it a long and do the install?

[WIDESIDE72]

You will need the ECM from the donor car if you are going to install an EFI LT1. I don't beleive anyone makes a carb intake for an LT1. Optispark are sort of trouble prone. I believe a recent issue of Hot Rod magazine discussed swapping it for a coil on plug system from a Northstar. Not cheap. I say install a rebuilt optispark during the swap and keep going.

[WIDESIDE72]

http://www.lt1howto.com/articles/optisparkfaq.htm

What is an Optispark and why do they fail?

The GM Optispark is an optically-triggered ignition distributor used on the LT1, LT4 and L99 engines. The "opti" has two parts, a low-voltage optical section and a high-voltage cap and rotor section.


What is it? The GM Optispark is an optically-triggered ignition distributor used on the LT1, LT4 and L99 engines. The "opti" has two parts, a low-voltage optical section and a high-voltage cap and rotor section.

Where is it? The opti is mounted on the front of the LT1, above the crank snout and behind the water pump. To replace it the water pump must be removed.

How does it work? The optical section consists of a disk with 360 slots in it, representing 360 degrees of crank rotation. A small laser/eye unit throws a beam through the disks and reads the pulses created as the slots pass through the beam. In this way, the PCM knows the precise location of the crank at all times. Spark pulses are timed through the cap/rotor side and injector pulses are also timed from this. When its working right, the opti is an extremely accurate timing mechanism.

GMHTP's Opti article is an excellent in-depth treatment of how the opti works.

Why do optis fail? Due to its location, the optispark is subject to moisture from several sources. First, driving through high water can submerge the opti completely. Automatic car washes with undercarriage wash can also soak the opti. Secondly, if the water pump suffers bearing failure and coolant comes out the weep hole, the opti can be soaked with coolant. Lastly, NEVER WASH AN LT SERIES MOTOR WITH A HOSE OR HIGH PRESSURE SPRAYER. To wash your motor, use a damp soapy rag and take your time.

Moisture buildup inside the opti can cause the precise parts of the optical side to rust up. The bearings are also weak and prone to faliure, particularly from misalignment or a too-long cam dowel pin distorting the drive mechanism. Last, high voltage causes ozone buildup inside the cap...which is to be considered a wear item just like any traditional cap/rotor distributor. Aftermarket ignition amplifiers make the ozone buildup worse and can significantly shorten the life of your opti.

What are my replacement/upgrade options? There are four basic options. (1) replace with a new GM unit. (rebuilt parts store units are of questionable quality). MSD now makes an upgraded cap/rotor of supposedly higher quality than stock if your optical section is in good working order. (2) The Dynaspark is a totally re-engineered unit with a billet body and improved moisture sealing. (3) the LTCC is an LS1 coil-pack conversion adapter to which you supply your own coils. It uses the signal from the optical section of your opti to work, so if you suffer optical section failure you'll still have to replace the opti. But, by removing the high voltage section from operation, you can significantly prolong opti life. (4) the Delteq opti eliminator converts the LT1 to a Northstar coilpack setup using either the Opti optical section or a stage 2 which eliminates the Opti all together

[WIDESIDE72]

http://www.delteq.com/

The Delteq Opti-Direct Solution



The Delteq Opti-Direct system solves most of the LT1's Opti-Spark problems by converting to a distributorless system similar to that used on the Cadillac Northstar engines. With high voltage removed from the Opti-Spark, the problems of cap & rotor wear, internal arc-over and cross-firing vanish. The rotor can be removed, preventing the problem of high RPM rotor failure, seen on many race applications.

The distributorless system consists of four high-output ignition coils, each firing two spark plugs. The four-coil system is able to produce longer charging time than a single coil system, even at high engine speeds, which means more energy to the plugs when it's needed most. The system is well-proven in its Northstar application with a stock redline of 6500 RPM and a recommended tune-up interval of 100,000 miles!

The Opti-Direct system is easy to install. Every kit is 100% plug & play, so no cutting, splicing or fabrication is required. Each application is custom-designed for a specific vehicle, so it's a perfect fit every time.

Included with the Opti-Direct system are:

Delteq Opti-Box (the "brain")
Plug & play wiring harnesses
New Delphi ignition module with 4 coils (the "coilpack")
Application-specific brackets
Custom 8mm double-silicone spark plug wires
Labels for coils and spark plug wires to aid proper connection
All stainless steel fasteners (No rust!)
Detailed instruction manual

Experienced "driveway mechanics" should be able to install the basic system in an hour, plus the time required to run the new plug wires.

Opti-Direct Requirements


The Opti-Direct (and every LT1 ignition system) uses the Opti-Spark sensors to determine crankshaft position and calculate the spark timing. Therefore, any Opti-Spark-related trouble codes must be resolved before installing the Opti-Direct. Unfortunately, this sometimes requires Opti-Spark replacement at additional cost. On the good side, Opti's seem to last longer without all that high voltage running through them.

Delteq offers a one-year limited warranty on ALL parts of the Opti-Direct Ignition System. The Opti-Direct Ignition System has been submitted for CARB approval.

[70c10lt1]

If you want to carburetor it Chevrolet performance parts has a manifold for about $300 and you can put a HEI distributor on it just like a gen 1 small block. Don't forget this has reverse cooling and a cam driven water pump that "CAN'T" be replaced with a gen 1 pump! the thermostat is in the water pump and there's no coolant in the intake manifold.

[dave69]

Thanks for input I should have explain that I will be swapping everything out I want EFI I just wanted to learn more about optic spark. Want to get away from carbs.