Ok so im not sure if anyone rememebrs my last post but saturday night i went to put my new optispark in and it ended up being defective, or at least i thought it was. I checked all the wires and timing etc and everything checked out fine. I put my old one back on and it started right up. Sent it back to jegs and they sent me a new one. I just put my new one back and and tried to start it up and same thing, its backfiring out of the intake and wont start at all. I called up jegs and spoke to a "technical salesman" and he told me that there were only 1 form of optispark made for the 94 lt1 and there was a 95 one that was vented, which him and i both agreed shouldn't make to much of a difference even if my car was a "late" model 94 and took the 95 opti. Has anyone had any problems like this when ordering the jegs brand opti distributer for a 94 LT1? Does anybody know what the hell it could be? Im really stumped now because why would my old one fire right up and the new ones wont? they look exactly alike. I guess my next step is to call chevy tmw and go from there. ANY SUGGESTIONS?

 

The drive mechanism for an unvented Opti is completely different than the one for the vented. They are not interchangeable, and won't fit on the same timing covers. Does your Opti have a splined shaft that inserts into the cam sprocket to drive it, or is it driven by the dowel pin on the nose of the cam?

If you have a 94, it left the factory with the unvented, splined shaft-driven Opti. There was no cross-over in late 94. It sounds like you are installing the unit with the splined shaft indexed incorrectly to the cam sprocket.

 

My opti has a splined shaft that inserts into the cam sprocket drive, i don't understand how it could be indexed incorrectly, isn't there only one way it could go in?

 

In theory, it only fits together one way. In actuality, many people manage to assemble it with the splined shaft indexed incorrectly, and claim they never forced it. I'd say 10-20% of the installs turn out to be indexed incorrectly.

 

i understand that but im 100% positive it is indexed correctly because it slipped right on every time i put it on (out of the 5 times putting the new one on then the old then the new etc) right after i lined it up as close to how the old one was as possible. For some reason it will only start with the old opti on, i don't understand it, both opti's are identical.

 

This won't help but ...
Are you sure Jeg's sent you a different Opti the second time?
My first BBK 52mm TB via Jeg's was of questionable quality (not Jeg'd fault as the box was BBK sealed) ... I returned it for exchange (on my dime). They sent the same unit back to me 10 days later. After a long phone session they agreed to exchange for another TB (on their dime). Another 10 days but they finally did send a different TB (somewhat better casting but no more BBK anything for me).
We're rooting for you.

 

Have you removed the cap and looked inside one of the distributors to see if you can determine what the “actual problem” is? Having had several opti problems myself, this has become a very common practice for me (taking them apart and finding the root cause of the problem). And, I can normally determine what the actual problem is.

A loose or damaged rotor is easy to spot. Also, inspect the center cap contact and terminal posts on the cap. Next you need to remove and examine the strobe wheel plate to ensure it isn’t bent, warped or has any debris on it (in the strobe holes). If the optical sender/receptor module is defective, you won’t be able to see that, however, you can check for debris in the module’s strobe slot.

Once the opti is apart, you can check the shaft and hub to determine if the shaft bearing is loose (has too much play).

WD

 

I just installed a 94 opti spark from jegs and thought I index it wrong till I
read this.This cxar was at no. 1 tdc before I pulled it off,engine did not move
that puts yhe index on the splines up.It slipped in with no force at all.Car won't start.Have done 94 opti before Idont know any other way to do it I yhink the new one is bad.

 

ha maybe jegs is sending out defective opti-sparks, i know they didnt send me the same one because i had them overnight me a new one before i sent the old one back. Im putting the old one back on tonight because i need to drive the car, my next guess is to take it apart and check if its another "defective" part. Now that i see someone else had the same problem as me (put new one in, car won't even start now), maybe ill try the gm one and see if that makes a difference. percylhd, let me kno if you figure out what the problem is with your jegs optispark.

 

Are you sure you've got everything plugged back end (opti, ICM, Coil, Etc). Just checking.

WD

 

Yes absolutely positive, i can't tell you how many times not only me and my cousin went over everything to make sure it was all plugged in and right. I even tried changing the ignition wire. I put the old one back in and it started right up. The only thing i did not do is take the new and old apart to compare. Im going to do that within this hour. Is there any way to check the opti's in or out of the car?

 

I've always had problems with the opti. 4th one now. I always take a new piece apart, modify (rivet rotor, they always break!) and inspect as posted before. I have a vented type, but, I remove the cap, rotate Cyl #1 to TDC, insert the opti to the camshaft, check rotor in position to fire cyl #1. B.

 

what do you mean you rotate cylinder number 1 to fire in tdc?

 

Rotate engine assembly so that both Cyl #1 intake and exhaust valves are closed and #1 piston is @ top dead center (tdc) or... top of stroke on compression cycle.
Then mount your opti. Rotor should be positioned to fire on Cyl #1 spark plug wire terminal in the distributor cap. The cap can be removed so that you can visually verify the rotoe contact is in alignment with #1 plug wire cap terminal. The cap can be removed by extrication of 4 screws. Hope this helps. B.