I purchased a 93 lt1 engine for my 96 z28 to replace the original motor.I didnt know this but half way through the year they changed the timing cover and opti spark design.Basically i had to put the opti and timing cover from the 96 on the 93 engine..My question is has anyone messed with this before and ,if so What did you do?How did it run..Mine runs awesome , especially when hitting the gas but I have a rough idle..I might have a misfire due to old wires I am not sure...ANY suggestions

 

there the same opti except the vent and plug in. so how old is the opti and if u know what kind is it? first thing clean the aic valve if it needs it. could be old plug wires bleeding to many volts, what about the plugs are they new?

 

You sure you got a 93 engine?
There were three different timing chain cover designs.
1992-early 94 was the old non-vented style opti.
Then about half year 94 came the new vented style opti, and a different timing chain cover.
Then in 1996 came a third cover design which housed a separate crank position sensor.
The opti is driven off the front of the cam, and the drive hubs/shafts on the two opti's are different. An opti from a 96 won't fit onto a 93-early 94 engine, unless the front of the cam is modified, or the cam gets changed. If you put the 96 opti right onto the new engine, then that means it's a 1994.5-95.

 

I already had the intake on it when i discovered the change so i didnt want to change the cam..You are right though I had to alter the 96 opti because it is a hub design instead of a little gear drive.I had to use the newer timing cover because of the cam sensor because the one i got with the 93 motor did not have any cam sensor ...Luckily it all works except i have a shaky idle..it idles under 1,000 rpm like it should just rough.When you step on the gas there is no hesitation at all. I have brand new platinum plugs but old plug wires....I purchased some Mallory pro sidewinder wires and they will be here in a few days so that might help... I have a performance cam setup for the car handy so eventually i will have to covert it but i just got it together couple days ago and I just want to use the car,,LOL How are the MALLORY wires? I always used MSD on my cars so I know nothing of Mallory...

 

Oh yeah,, I forgot to mention that the older opti was not vented and the 96 opti is a vented distrubutor like you said so that was another reason I had to use the one my z28 originally had on it...I figured the computer would not like a missing cam sensor, non vented system..(not run) These opti' s are real crazy!!!

 

Crazy ain't the half of it! Is your opti new or used? What did you do to alter the opti to fit the old cam? If it's a used opti, did you clean the optical reader under the tin shroud, and put on a new cap and rotor? These things get crapped up inside, and if all you did was an r&r, then that just might be the reason for your idle shakes. But I would start with your wires since that seems to be on the menu anyway. I haven't used Mallory wires on the LT1, used MSD with no problems though.

 

I had to cut a half inch off the hub on the 96 opti to fit it..The cam pins are also slightly different so I am guessing the opti is being driven by the cam gear bolt that goes in the hub.The pin is shorter on the older block I think its a 93 block.I didnt think it would work either but it did some how.It must be working because it accelerates flawlessly..I put a new fuel filter on earlier and it idles much better...If the new wires i ordered dont work I am going back to the opti like you said..I did clean it up but it was a used oem replacement so it will need an uprgrade either way...Thanks for the advice camaro 69 I will give an update om it in a few days..

 

wow. how did u line it up when u put it in? never heard of anyone doin a opti install like that. lol.

 

would an opti just crap out on you with no warning at all, no misfires or nothing? ran perfect and then all the sudden kill your car with no restart....im having a heck of a time figuring this out and im hoping its not my opti!

 

So now it's d.o.a.? I'm still curious how you converted the opti. Did the splined shaft from the old opti fit into the new one after cutting down the hub, or what? Don't spose you took any pictures? And are you sure you had the timing dead on the way you adapted it?