I PUT IN A NEW OPTISPARK ON MY Z28 YESTERDAY IT IS A NON VENTED ONE FOR THE 1993. THE NEW OPTISPARK CAME OUT IF THE BOX READY TO INSTALL WITH GEAR IN IT, PUT IT ALL BACK TOGETHER THE OPTISPARK WENT RIGHT IN AND PUT IT BACK TOGETHER AND IT CRANKS LIKE THE TIMING IS 180 OUT CRANKS HARD, THE ONLY THINGS I CAN THINK OF IS I BROKE THE AIR CONTROL MODULE PLUG, WILL BE REPLACING THAT SOON, BUT YOU TAKE OFF THE COIL WIRE IT CRANKS GREAT. ALL PLUG WIRES ARE RIGHT ALMOST LIKE IT HAS AN AIR LOCK ANY ONE KNOW OF ANY THING I CAN DO FOR IT , I ALSO HAD TO MOVE THE BOTTOM CRANK SOME TO GET THE NEW OPTISPARK IN THAT I HOPE WONT THROW ANYTHING OFF THE CAM AND CRANK ARE ON A TIMING CHAIN. THANKS DAN

 

You have to index the splined shaft correctly to the teeth in the cam sprocket. While it appears that it can only go in there one way, I'd estimate that about 10% of the installs go wrong and are not indexed correctly.

Courtesy of Shoebox:

http://shbox.com/1/93-94_opti.jpg

You also need to check all your plug wires to insure you have them on the correct Opti terminals.

http://shbox.com/1/opti.jpg