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Installed new opti-spark in 92 base corvette and now won't start


Active member
Sep 5, 2020
Beaverton Oregon
92 base corvette
Hi all, I installed a new Cardone opti-spark and now won't start, When I got it I did the vent mod on it then when I went to install it it wouldn't fit flat against the timing chain cover, even with out the spline shaft attached. It turned out that where the spline shaft when in, the base plate protruded out to far preventing it to fit flush against the timing cover. Because of the mod I did on it, there was no returning it. So i used my base plate and swapped everything over to it and fit fine but now it won't start. I get spark to spark plug and getting fuel to it as I pulled a couple of plugs and they were wet with fuel. At the same time I installed intake, timing chain cover, oil pan, valve cover gaskets alone with any seals. I also adjusted the valve lash too. Could the opti be putting out spark and still be bad? Could the spark plugs be bad now because of fuel on then, even though I changed them a month ago? Please help because of the bad fitment and a lot of time just pulling the hub and bad weather, I have been working on this for three weeks now, please help!!!
I had similar issues when I swapped the opti on my 94....but I can't remember what the problem was.
GMJunkie Where are you?
Yea, I'm thinking, 40 to 45 is where it should be.
42-47 psi at key up is what the big boys down at the pool hall claim it should be.
Check the FPR for leakage at the vacuum line,If there is fuel in it, it's faulty!
Otherwise I'd suspect the FP.
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I was going from my (poor) memory. I knew Junkie would know.
42-47 psi at key up is what the big boys down at the pool hall claim it should be.
Check the FPR for leakage at the vacuum line,If there is fuel in it, it's faulty!
Otherwise I'd suspect the FP.
Put fuel pump in and when I went to try to start it it seemed to try to start then I got a back fire from the intake. So it must be some kind of timing problem. Now remember I transferred everything from the new opti to the old base because it wasn't fitting right, I was real careful to put it back correct , but it would be the first time I screwed something up, but what?? How would the timing be off? I also adjusted the valve lash by three different methods but got to thinking that isn't there a chance the they might collapse some and the adjustment are off?? I might add then the car was running before I stated screwing with it.
Ok, when I swapped to roller-rockers I didn't get the valve adjustment quite right and it acted just like you are experiencing. I'd go back to and readjust the valves. Did you check fuel pressure at the injector manifold? Those fuel pressure regulators are a common problem.

Yeah,I'd go with checking the valves again,If you have them too tight it will act that way! Re-Man Opti- Sparks suck Big time too! I've got them NEW right out of the box and they wern't worth the powder to blow them to hell! LoL!
I brought it to TDC right after intake closed and adjusted the as shop manual says but back then all the way out till whole rocker wiggled then tighten till no up and down movement then 1/2 turn. Took opti apart to see if I put together right now no spark anywhere. fuel pressure at 40# key on and 44# crank and held for hours.
Following this. Wondering why so many issues with Opti's. Like Junk says parts are not reliable and bad out of the box. Hope you made out okay, please post when it's rectified.
Another "trick" or method to use when adjusting rocker arms to ensure you are not going too far and collapsing lifters is to rotate the push rods while tightening the adjusting nuts, don't worry about rocker arm movement, and when the push rod stops rotating, then use 1/2 turn more.

Built hundreds of Chevrolet engines and this is the method I use to adjust valve lash on all of them.
Here is up date. After installing fuel pump and a day after getting that backfire out of intake, I stopped getting spark. Bought a AIP opti sill no spark. So someone suggested that it might be the ICM, so I replaces ICM and STILL NO SPARK. WTF. I'm lost guys as to where to turn next, This three day repair is going on 6 weeks now and really getting down about it. Need all experts, Please!!!
When it stops raining I'm going to have to check out this 93 I have here to verify what I think I remember! LoL!
Meanwhile, Check at the back of the engine to make sure that the bracket at the back is not chaffing the main harness to the ecm! They have a problem with that.
OK, I followed the FSM Chart C-4 Opti-spark ignition systems check. No spark coil driver connector pins A and D 11,6 dcv, coil driver connector B 4-7 ACV while cranking, coil driver connector C good ground, So according to FSM faulty coil driver connector bad or faulty coil driver. It has a new coil and ICM so if I'm getting good reading how can it be the connector. A few days ago I was getting very confusing reading , come to find out coil fuse blown and one for the ECM, BUT STILL NO SPARK!!!

I also checked the opti connector and 12 DCV on yellow and 5 DCV reference on pin A and B, good ground on pin D

Where should I go from here?????????
Junkie will check in here shortly and give you a suggestion.
How did you check the ground,Test Light or VOM?
I had a White 94 6 sp that gave me fits like this a few years ago (probly 8-10 years now) that I had all ready to deliver to a new owner and it just quit, after I replaced the Opti, ICM, Coil, Plugs and Wires still No start.Tom even sent me his back up 94 ECM because I thought mine was bad but that wasn't problem. Still NO GO! I've been looking for the thread to see what I finely found to get it running. (I've had 2 Hearty Acks and a mild stroke since then) This new software that Rob installed on the site is completely different and I can't find the thread it was in. I'll get in my files in the office and find the jacket to the car and find out for sure what I did,I've sold probly 250-300 or more cars since then. Stand By!

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