LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Absolutely craziest optispark question ever...

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Old 03-11-2007, 06:50 PM
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Default Absolutely craziest optispark question ever...

I feel like a major moron here. Now that that is out of the way.

The reason my new engine would not start is because the opti timing was off. Let me explain.

My functioning GM opti I took off a previous running engine just needed cleaning and the bearing lubed and it would then be golden again. I took the opti completely apart including pressing the two piece shaft apart. I took the bearing seal off and packed the bearing with grease an re-assembled.

Here is what happened, I did not take into consideration that the two piece shaft that goes through the opti base MUST BE PROPERLY INDEXED or the ignition timing will be off. This is the reaon my old opti did not work on my new engine. I cant believe I wasted two full days as a result of this oversight. This clearly explains why I got the DTC 16 low res pulse error.

When I installed a brand new Accel opti the engine fired right up because the two piece shaft had never been tampered with.

I just indexed the two piece shaft using using the #1 on the back of the opti base as a reference point. I bolted the rotor button to the top shaft and pointed it at #1 location using the terminal in the cap as a reference point. I indexed the rear shaft and pointed it to the #1 on the back of the opti base. I then presse the two pieces back together.

I am thinking that when this process occurs during actual assembly of the opti in the factory that there is a range for the indexing to occur. I think if it is off a few degrees one way or the other then the PCM can compensate for this. Maybe I am wrong at it is super critical, this is what I need to know if anyone has the answer.

Using the above procedure this the engine is now running on this re-indexed opti spark. It will be a several days befor I can drive it. It looks like I have sved it.



This is what I am talking about:


Does anyone want to sell me a used busted opti send me a PM. I just need the base and rotating shaft. I dont care about the cap, rotor and sensor. Just make sure the shafts have not been taken apart like in my photo above.

Last edited by wrd1972; 03-11-2007 at 08:10 PM.
Old 03-12-2007, 01:59 AM
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wish I had a spare for you, pretty cool how you tore it down and learned about the indexing, I figured that little bearing was sealed, hmm. Where are you located, if I can find a buddy with a spare (at least the guts) I'll see what it'd take to get it to you. You just need the back half with the Mitsubishi eye sensor, bearing/shaft etc not the cap right?
Old 03-12-2007, 02:15 AM
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PM sent
Old 03-12-2007, 02:22 AM
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I have 1 has 73K on it never been tampered with I just took it off for my rebuild it is a little dirty from a seal leak but it was working when i removed it. Send a PM if interested.



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