Been awhile need help with 94-95 lt1

[DustinZ28]

Hello all,

Been a while since I've been on the car forums but I'm back and Yes I've searched but it hasn't really helped me.

I got a 95 m6 Z with a cracked head or blown head gasket. It's been sitting for 3 years. I have stumbled across a built 355 out of a 94. I'm trying to find differences between a opti's etc and I've heard a lot about the down pin depths etc. The motor has a comp cam in it.

What would I need to do to get this motor in my car?

Thanks for any and all help

[Injuneer]

94 has an unvented Opti, driven by a splined shaft that inserts into the cam sprocket.
95 has a vented Opti, driven by the cam dowel pin.

(Courtesy of Shoebox)




The timing covers are different, to accommodate the larger hole required for the dowel pin to rotate.



The cam sprockets are different, with the 94 having the splines for the splined drive shaft, and the 95 having a larger hole for the Opti pilot shaft to pass through.



Since the 95 pilot shaft has to rest in the cam nose, the hole in the 95 cam nose is larger.



The harness connectors are different - 94 has a short connector, 95 has a long connector. You can just swap the short harness from the bracket on the side of the intake manifold to the Opti.

Shoebox has info on the cam dowel pin required for the 95-97 vented Optis:

http://shbox.com/ci/ci289.jpg

Before you install the cam, it is a good idea to check the dowel pin length. Compare the new length to the old and make any adjustments if needed. If the dowel pin is too long, it can ruin a vented optispark in a short time (non-vented optisparks aren't driven by the dowel pin). Some have said GM specs indicate that the dowel should be .620" long (protrusion from the front face of the cam) for the vented optispark. Others have said it is supposed to be .685". Mine was actually .650" and still was in no danger of bottoming out in the optispark drive (I'm thinking .685" might be the max it could be). Here you can see the difference in the Comp Cams dowel (right) to the original. The CC pin was .840". That would put pressure on the back of the optispark and destroy it in a short time. If you have any doubts about the length, use some modeling clay (even PlayDoh :-) ) to test fit the opti and check the clearance. Comp Cams advises you to check all clearances.


If you don't want to change the pin, it can be dressed down by a grinder with relative ease.

[DustinZ28]

Wow, thank you! Seems like I remember you from other sites in the past.

I honestly forgot all about shoe box site it's been so long since I've messed with my car.


I will be getting the motor - all accessories, Etc. So I will have to use my front cover. Would I have to change the cam seeing mines a '95?

[DustinZ28]

Anyone else? Any ideas what I would need to do with the cam? I don't mind buying an opti so that isn't an issue.

What about computers, are those the same? I might could work a deal to get his tuned computer with the motor if it will work

[bowtiedad_z28]

If you are going with the complete 94 motor with its cam you will only need a unvented, spline driven opti if it doesnt come with it. Assuming the new motor has not been converted to the 95-97 setup already. The 94 and 95 computors are the same. Both obd1. If using your old computor you will need it tuned for the new motor as you say it is built. You will also need a 93-94 opti harness connector if using the spline driven, unvented opti. The plugs on the opti end are different.