I am swapping a rebuilt LT1 (355 w/ forged internals) from a 92 Corvette into my 95 Z28. The Corvette motor has the old-style Optispark (92-94) with the gear drive (instead of the later dowel-pin drive) and a funky 5-pin connector to the wiring harness. My 95 Z has the later-style Optispark, and a 4-pin connector. I figure my options to make everything a happy collection of working parts are as follows (from easiest to hardest):

1) Rewire the old Optispark wiring harness connector to use the 4-pin connector that came on the 95 Z. But what the hell is that fifth wire that my Z doesn't have??

2) Swap over the Optispark, timing set, and timing cover from the 95 Z. This is mostly an easy proposition, except the camshafts for the earlier LT1s (old Optispark) had a much shorter dowel pin because the distributor was driven off the center gear. So this means I have pull the press-fit dowel pins on the end of both camshafts and swap the longer one over. Sounds easy, but the little bastards are press-fit so tight they're nearly impossible to remove. Any ideas of how to do this?

3) The above but just get a new cam with the correct long dowel pin already inserted. I guess this could be an excuse to upgrade to the Hot Cam Kit, but I really don't want to spend the $$$$$$ right now for that......

Any input on my dilemma???????

Thanks all.

 

Just buy a new harness. It runs from the optispark up to the passenger side of the intake manifold and clips in there.

Many guys convert the 92-94 style to 95+, and thats plug and play. Dont see why doing the opposite would be different.

 

Any idea where to get one of these cross-breed harnesses? The old-style harness has a very short connector (maybe 1 inch) that plugs into the Optispark, where the new-style one is about 3 times longer. By length I mean how far it inserts into the Opti.

So I guess the correct harness for me would have the short 92-94 connector on the Opti end and have the 4-pin connector to the Z28 wiring harness on the other end...

-C

 

Its not so much a cross breed really. The end that clips in by the intake manifold is the same on both of them, the opti end is just different. I have read that some cars going from old to new style, they need to knotch the clip a tad to make it work? NOt sure on the details of this, mine was a direct clip in.

Im sure a bunch of people around here have them as its a popular switch to go the other way, so they took off the one you need from their car. Ask for a 92-94 "opti pigtail"

On the 95+ style you have high res, low res, igniton feed, and low reference. I cant tell you what the 5th wire is for??

If you cant find one here, go to GM or a junkyard and get one

 

I get it. The kooky 5-pin connector on the non-Opti end of the pigtail is a Corvette thing, not an early LT1 thing. So a pigtail for a 93-94 F-body will have the same, shorter Opti end AND the correct 4-pin connector on the other end for my Z's wiring harness.

Thanx a lot for your help.

 

For the vented opti, the cam must also have the big hole in the front. It is not just a matter of the dowel pin.