I'm in the middle of replacing my 4th OptiSpark. This one went almost 5 years and about 40k miles. At least this last one didn't completely die 100%. It will start and run badly, but it barely got me inside the garage where I can work on it.
I think this one had some mechanical failure instead of the usual total electronic death the others had suffered. I'm thinking there might be too much slop in the 90k timing chain and the Opti got jerked around till something came loose/cracked!
I know the LT4 has a single row roller chain that looks pretty thin compared to most aftermarket double rollers. My question is; What is a good replacement chain for the LT4 that will fit under the front cover without grinding away much on the cover for clearance. Any good aftermarket chains available or should I just pop for another new stock LT4 chain and sprocket kit?

 

get an LT4 "extreme duty" timing chain; yeah they're expensive but they look like something that came out of a sawmill...rugged..and no mod's needed

 

I updated my 94 to the optispark II and used a cloyes chain/sprocket kit. on the 96 I found a cloyes chain #9-4190 from o'reillys for under $20.

 

I don't think so. 90 K is not that many miles; my '96 silverado has 270k on it, original cheapy timing set, and my 'Vette has ~160k, opti is fine being "jerked around" what ever amount it gets "jerked around".

I'd think it's much more likely that the rotor screws came out.

 

Thanks for the info on the chains. Don't think the screws came out because I put the RED lock tight on them and torqued them to 10 inch lb. with my little torque driver. I had planned to never see the insides of that thing again.......BUT, I'll be seeing it's inards sometime this weekend when it gets cool enough to go back in the garage again. Having 95*+ days here in San Antonio and when the sun starts going down, my west facing garage doors are like the sides of a Pizza oven! As fate would have it, my nice big garage fan took a dump yesterday too. The little cooler I have out there now would be fine if I was working in an elevator or a phone booth!. Looks like late night under the lights to get this thing back on the road again.

 

And when the sunsets the biteing bugs come out!!!!! Get two liter pop bottles cut the top off and invert it in the bottle cover the outside of it put water brown sugar and yeast in it bug trap!!!!!

 

Yikes...that a bunch of unfortunate circumstances coming together! Bummer man! Good luck w/the tear-a-part. Looking forward to your findings.

 

Got the whole thing pulled apart now. Been too busy lately to really put much time into the thing.
I pulled the Opti apart for an autopsy and didn't really find anything catastrophically obvious inside. My custom modified rotor was still in place.(I extended the tip .095" closer to the cap contacts because the stock gap .127"seemed excessive.) There wasn't any water intrusion but there was a slight film of oil that I think came from 5 years of breathing K&N filter oil through the fresh air breather tube, and maybe enough to finally cloud the photo diodes. The under side of the cap and the rotor button showed some scorching and blackening from the HV sparking over the years but was probably normal for the miles on it. Probably time for service on those anyway. It's a shame they made the thing damn near impossible to service until it craps out completely. I'm still in the cleaning and inspecting stages so I no hard causes of failure found yet. I'm going to OHM out the coil wire just to make sure it didn't break down. On with the new stuff as soon as I can brave the heat again.

 

I too vote this works well. I am using the cloyes version of this. This has the advantage of coming with 2 additional key ways to either advance or retard your cam 4 degrees if you desire.

I'm not a fan of the electric water pumps which is why I went this route as opposed to the electric water pump/double roller route

If you go this route:
Be aware there are some boneheads here and on the camaro site who have screwed up this mod.

It seems if you don't replace your waterpump drive gear with the one supplied (requires a press and likely replacement Bearing as that one will likely get destroyed), you will run into issues.

The metallurgy is different and the stock one will still fit but eventually gets chewed up sending metal pieces throughout your engine. Requiring an engine rebuild.

Other ways this gets messed up is the Freeze plugs? Have some oil holes in them to spray oil into the timing cover (onto the chain I think? ) These can get blocked. One of these oil holes was blocked with a piece of gasket material that had found its way in there from a previous tear down. Some people have even enlarged the oil holes slightly as mine were the size of pinholes. I don't think I enlarged mine but certainly made sure mine were clear while I had it apart.

Next Use a lot of that red cam break in lube on everything. Soak that chain in oil before installing for the first time!

I did this 20000 miles ago and it works great. I have an aggressive cam ramp profile and heavy valve spring seat pressure.

This chain setup has worked great.