1993 LT1 Opti Replacement

My optispark died last summer with no warning and no water leaks. My first thought riding home in the tow truck was dead fuel pump. Nope, fuel pump tested good. Checked spark out of coil, also tested good. Checked for spark at 2 of the 8 cylinders, no spark.
I completed my conversion 10 years ago (1993 Corvette LT1 in a 1977 XJ6) and have never touched the opti.
I wanted to try replacing the optical sensor in the opti.

With some extra time this month I removed the opti. Upon removal and disassembling looks like I will need to change coarse on my planned repair.
The rotor was completely distroyed, there is surface rust on most of the metal pieces inside the cap and the bearing is completely siezed.
I cannot find a replacement bearing, 17mm ID, 35mm OD, 5mm thick. That stops me from rebuilding it.
I believe I am going to go with the Petris replacement optispark. Can’t find any Delphi’s or AC Delco’s. Any body tried one? It comes with a 1 year warranty and the added venting kit improvement. A little pricey at $400.

It looks like my water pump was weeping coolant out the drain hole onto the opti. Ordered a new water pump. I noticed my coolant is very, very rusty! Will do a good flush to try and clear it out.
Is there any kind of additive for the cooling system to help get rid of the rust?


Summit have the whole thing for $240 I think?
But for the coolant, flush a lot and with good 50/50 you should not get a lot of new rust with the included anti-corrosion additives, although some will keep dissolving into the water and you‘ll have to live with it.

The thing looks cheap. Cheaper than hundreds of dollars? Breakyard?



I believe it might be the original optispark, has a Mitsubishi optical sensor.


Aye, the classic OPTI failure. Weep from the water pump.
And, as best as I can tell, yours is the first version, sans venting! the venting is to draw any moisture that gets in to the intake. The second version, as you say is vented. And supposedly sealed better.

Tales of it’s “weakness” caused me to install a brand new late version on preparing my LT1. Done in the car, but before the radiator was mounted. Not easy but doable. I had the tools to pull the crank pulley. Alas, on pulling the WP, I busted the drive!!! That little shaft is cast iron!!! More tear down?? NO, I found Mezzierre. An electric pump! A bit pricey, but has been great… “knock on wood”. Bye, bye, WP weep issue.

I like David’s idea. Get an OpTI from a “junk” yard. Who knows, fantastic luck might reap a new genuine unit!!! If not, at least a source for the unobtainum bearing. Make oe good unit outta two.

But, then from 93 til now, pretty durn good service.

Carl ,

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