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Optispark identification

Old 12-17-2018, 06:14 PM
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Optispark identification

Hey guys, I recently picked up a LT1 from a 1994 Chevy Caprice to have as a spare LT1 block, I have a question about the optispark. Does the tube that goes from the opti to the air intake mean that it's a vented opti? Also, other than installing and testing it, is there a way to check and see if its working properly? Thanks guys.


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Old 12-17-2018, 07:47 PM
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Re: Optispark identification

Take the cap off and inspect for rust.

Some people have done bench testing, but if it's not rusty inside you're probably good to go.
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Old 12-17-2018, 07:55 PM
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Re: Optispark identification

Ok, where can I get the right torx socket to get the cover off?
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Old 12-17-2018, 08:27 PM
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Re: Optispark identification

Originally Posted by Jdblood202 View Post
Ok, where can I get the right torx socket to get the cover off?
It's an E-4 torx. You can also use one of the screws from the throttle body cover in a pinch. Lot's of threads (ha!) on the subject - here's one;

https://www.camaroz28.com/forums/lt1...ispark-474865/
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Old 12-17-2018, 08:34 PM
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Re: Optispark identification

Awesome, thanks!
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Old 12-17-2018, 09:04 PM
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Re: Optispark identification

Take the harness connector off your current installed Opti. Plug it into the spare Opti, and connect a ground from the Opti metal casing to the block. Turn the key to “run”. Hook a volt meter between the red/black wire and the pink/black wire. Slowly rotate the drive. In one full revolution of the distributor drive, you should see 8 slightly uneven spaced, variable length pulses where the voltage jumps from 0 volts to 5 volts. That would confirm the low resolution signal.

Now measure the voltage between the purple/white (or light blue/black) wire andthe pink/black wire. Rotate the drive slowly. In one full rev of the drive, there will be 360 even spaced, equal length spikes from 0 volts to 5 volts. Don’t try to count them, just observe it appears to match what is described. That would confirm the high resolution signal.

Note that the optical module may fail intermittently when it heat soaks under actual engine heat. Difficult to test, unless on a bench.

Schematic from Shoebox

http://shbox.com/1/95_ign_system_schematic.jpg
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Old 12-17-2018, 09:08 PM
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Re: Optispark identification

To answer your first question, it is the vented version.
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Old 12-17-2018, 09:20 PM
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Re: Optispark identification

And yes, it’s a vented Opti in the photo. In addition to the two hose connections, it has the cam dowel pin drive mechanism used in the vented 95-97 F-Body LT1. The Caprice got the vented Opti in 94. The unvented 93/94 unit has a different splined shaft drive.

From Shoebox:

93/94

http://shbox.com/1/93-94_opti.jpg

95-97

http://shbox.com/1/opti_back.jpg
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