2 months later and shes still running great
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On my 93 Z28, at about 120k my factory optispark bit the dust. It all started one morning.. I got off work and went to Walmart, upon leaving my car would crank and crank and crank but it would not start. I popped the hood and found an odd puff of smoke in my intake elbow but at the time I wasnt aware of the implication of this. I kept trying and EVENTUALLY she did start and I was able to make it home. I got the high resolution signal failure code and an ignition control code. I crossed my fingers and changed the Ignition Control Module and the Ignition Coil since its alot cheaper than the opti. After getting the new ICM and coil in, that night I was just double checking everything with a flash light and I come to find out my coolant crossover/steam pipe sprang a pin sized hole leak where the metal pipe(that runs from the back of the heads to the end of the valve cover between the alternator and throttle body) meets a rubber hose that has a factory metal clamp fitting that runs to the radiator. It was in the perfect position to leak down onto the distributor and cause a failure. If I hadnt had the flash light on it to see the ever so slight mist of water coming from that pin-hole leak.. I might've never noticed it at all. She drove fine for another month then again as I was driving home in the morning, I noticed the slightest of power losses.. probably more like it slightly "bogged down" and my speedometer went wild for a moment but still I made it the 45 minute drive home though the SES light came on again warning me of high res signal failure. I figured it was finally time to deal with the issue.
My options were 1- AC Delco OEM replacement at 400 bucks or so, 2- the nice MSD opti for about 480, 3- the duralast at 160, or 4- the cardone at 250 something like that. i called up a guy i know who has a shop that almost specializes in LT1's and he offered me an MSD he had lying around for 450 and I was going to accept, however you cant just get any old opti as there is a difference between 93-94 (non vented allowing gasses and moisture to build up in the unit, spline driven) and the 95-97 (vented requiring a vacuum line connected to it, also cam-dowel driven). This guy had the 95-97 and I needed a 93-94, but even a quick google search will tell you that the quality of MSD opti's seems to have fallen over the years and many report bunk units right out of the box. Obviously when you give autozone the year of your car they will set you up with the right one but if you buy one from another source, pay attention.
So my local autozone had me one 2 days later and I set to work. Probably the most annoying thing about the disassemble was taking off the harmonic balancer\crank pulley. You DONT have to remove the center hub or the bolt in the center, just the 3 bolts that hold the actual pulley onto that center hub. That said, those 3 bolts were kind of a hassle as the pulley moves when you try to turn the bolts. I got the bolts out by jamming a crow bar into the open slots on the balancer and the other end against the radiator support. Then the balancer was on the hub pretty good so I had to take a 2x4 jammed up against the back lower side of the balancer resting in between the sway bar and the oil pan.. and a big ass hammer and wail on the that section.. then rotate it, and wail on it, and just keep beating on it and beating on it until it comes loose. Probably took me a good 30-45 minutes just to get that balancer off.
Aside from the balancer, it wasnt too bad of a job.. the rest of it was pretty cut and dry and quick going. I figured I would do the intake manifold gasket due to an oil leak out of the back and the water pump drive seal and opti seal on the timing cover. When I had removed my opti, there was quite a bit of oil behind it on the timing cover and its just a smart thing to REPLACE THOSE SEALS while you are there. I took my opti apart and noticed some oil built up in it so I think that was the last straw for it.
One thing worth noting is that this Duralast unit COMES with the pigtail that goes from the top of the opti to its connector on the wiring harness right near the Evap Solenoid. This is nice but it was kind of unexpected as it doesnt tell you that it actually comes with it. I had intended on replacing this as well but we looked through their system and couldnt find it listed individually and I even had some trouble finding it in a google search on my own. Also when reinstalling mine.. I plugged in the pigtail at the opti and then dabbed a bit of black rtv around it to kind of "seal it off". I dont know if it helps at all but it certainly cant hurt and the last time I had done the water pump, I noticed that the previous owner of the car had done the rtv around the connector as well.
When you go to put the new one on, the spline drive has a keyed section that is a little hard to notice. It has ridges on it and on the keyed section one of the ridges is a little bit bigger. DONT TRY TO FORCE IT IN. If you can, take a flash light and peek into the hole and you should be able to see where the key is. You could also take the actual spline drive out of the old opti and use that to feel into the spline and then just adjust the position of the spline on your new unit.. though the opti itself has a couple weird headed screws on it.. and it took about 45 minutes to get it completely apart. Im kind of a novice and I was able to make due with simple tools. I kept the entire broken opti unit just for if I ever get curious about the internals of it and definitely kept the spline drive incase I have to do this job again.
Anyways, when I got all done.. the car fired up immediately and I have not had a single issue whatsoever.
Pros: Cheap, half to a third of the cost of other brands, comes with pigtail
Cons: Risky purchase due to the bad reputation duralast optispark's have