Does anyone know if the opti harness (the short one that goes from the main harness to the opti) does anything special ? If so, What exactly does it do.. Thanks, Artie

the opti determines timing and crank position through that connection. It has an internal optical sensor that detects this hence the term "opti"

hope that helps

I'm talking about the harness itself...Not the actual opti...
the reason i am wondering this is because I am missing this harness and it is $50...I was wondering if I could make the harness myself of do I have to buy one..

Thanks, Artie

not following, that is what the harness does.. transmit these signals from the opti to the ecm.. if you have the right connectors and pinout, no worries..

as for anything special, it is just wires and a plug if you can find the right parts no problem..

Any idea why they even had that short connector in there...Why didnt they just make the harness long enough instead having that short connector in there ?

Same reason they put the optispark under the waterpump. Same reason these cars came with a 10 bolt....its a mystery.

as far as I know, its just a straight through cable, just an extension. But, as you probably already know, the optispark connectors are different between 94-earlier and 95-and later. Make sure you get the right one.

By the way, I have been looking for this piece for awhile now. Where did you find a price of 50 bucks for the harness? Its funny, I was gonna just post a request if anyone knew where to get that piece, since i'm also missing it from one of my conversions.

It is GM part number 12106559
www.gmpartsdirect.com

Not sure why they made it seperate (a better question is why they put that ill-conceived POS on the LT1 to begin with...a single coil pack would have been cheaper and far more reliable). There isn't a whole lot to the harness, and you probably could make one fairly easily IF you had the connector that goes to the Opti...which is a fairly long connector that I have never seen on any other GM application. You might also try Street&Performance, they sometimes have used ones for sale from motors they did carb/distributor swaps on.

thanks for the part number! is that for a 95-up LT1?

yeah, if you can get the part numbers for the connectors, you could probably get samples from powerandsignal.com, and make the cable for a few bucks, if that.

thats the 93-94 part number...
I can get you the 95 number tomarrow if you want..

95+ part number is 12130319

Here is a list of part numbers for everyone...Hope this helps some of you

http://shbox.com/1/Parts.htm

hey, thanks again, great link too, I've got that bookmarked!