replacing the opti

[Achilles]

I need to replace the opti - spark on my 95. Is this a difficult project, or should I take it to have it done?

It's mainly an issue of available time for me. Can I do it in a day or two?

Also, if I decide to do it myself, is there a website with step-by-step instructions?

Distributors, I've delt with. But this is all new to me.

 

[Toms007]

It's not that difficult to change the opti out. More an issue with time. If you are pretty handy, have a decent selection of tools and the time you can do it. FSM isn't required but handy. The FSM sometimes assumes the person doing the work has some general knowledge, but nothing that can't be overcome with just stepping back and looking the situation over to determine what needs to be done.

I had the whole front of my 94 apart (replaced the opti, w/p, wires, and seals in the timing cover), it was pretty straight forward.

 

[speedmaster4]

not that hard a job if you have dizzy experience, prolly less than a day... i carry a spare opti, and tools to swap over, in the trunk of my lt1 roaddie for abt a 2 hr road repair if req'd.

hints:
there are SIX bolts that hold the water pump on rather than four as older small blocks, + two ''guide pins'' that corrode and the pump seems welded to the block...wiggle/tap GENTLY with a wooden block/hammer AFTER all SIX bolts are removed.
harmonic balancer has an ''arrow head'' cast into the hub,note position, visible BEFORE removing the harmonic, which is req'd to remove the bottom opti bolt (which all three are 3/8'' not metric) and to pull off the opti...likely will need your old-time sbc harmonic ''puller'' to pull the harmonic off the hub due to rust messing up oem ''slip-fit'' (hub stays on, don't remove the crank end bolt) and the (3) harmonic holes for puller attach are tapped 5/16-18 NC (not metric)
look at the drive for the new opti very carefully before installing, you can see the req'd positioning of the drive into the opti but easily overlooked...the opti will seat FULLY into place ONLY if the drive is correctly indexed -- do NOT ''draw'' it down with the (3) opti mounting screws.

 

[Achilles]

Thanks for the help. I've got some mechanical engine experience - just not with this animal. But I'm going to get started on it today and hope all goes well.

 

[LT4man]

Check out this post. Tells you everything you wanted to know about optispark replacement but were afraid to ask!

http://corvetteactioncenter.com/tech/c4/optispark.html

Keep in mind the surgery was performed on a Trans Am.

SAVE THE

 

[Achilles]

Thanks - That is perfect!

 

[jrzvette]

While you're in there plan on replacing the water pump. You'll have to remove it to get to the opti and you sure don't want the old wp to fail two weeks after you've done all that work.

It's also a good idea to change the plugs and wires.

Not trying to give you extra work but it's just easier to do it all at once.

Are you planning on using an OEM opti or an MSD?

 

[Achilles]

Ok, I'm finally into this thing and I followed the instructions that were provided. Now I'm down to the harmonic balancer pulley and the opti-spark.

I'm puzzled as to how the HB is going to come off with the steering rack in the way. There is only about 1/2" clearance before the pulley hits the rack. The instructions were for a T/A which may be similar but different.

Does anyone have first hand knowledge on what I do next? I'm working on a 95 vette.

Sorry, I don't have a repair manual, so I need someone's expert help.

Thanks

 

[bradfordsvettes]

may be all wet here but i have done quitw a few optis and have not had to remove the balancer pulley but they were earlier cars just my 2 cents Steve

 

[speedmaster4]

pulley must come off to remove the bottom opti retaining bolt...but JUST the pulley, the hub stays on the crank...observe that the ''shoulder'' of the hub only extends abt 1/4'' beyond the pulley = room to remove...note the position of the ''arrow'' cast between the legs of the pulley for later re-install...the pulley is originally a ''slip-fit'' on the hub but most rust on and will need a puller to remove.

 

[Achilles]

pulley must come off to remove the bottom opti retaining bolt...but JUST the pulley, the hub stays on the crank...observe that the ''shoulder'' of the hub only extends abt 1/4'' beyond the pulley = room to remove...note the position of the ''arrow'' cast between the legs of the pulley for later re-install...the pulley is originally a ''slip-fit'' on the hub but most rust on and will need a puller to remove.

Ok. I appologize for my ignorance, but can you explain the process of removing just the pulley. From what I can tell the pulley and the balancer look like they are one piece. I don't get what the hub is or where the mark is located. I see 3 bolts inside the pulley with a center crank bolt. I have a HB puller, but I'm unclear what I'm removing and how to remove it.

I guess I should have gotten a repair manual before I started, but it sounded like a simple operation and maybe I'm making it more complicated than it really is. But I've only worked on the old style SB engine.

Thanks for the help.

 

[speedmaster4]

unlike the sbc1 HB, the lt1 HB is two parts, the center hub and the three-leg casting/outer ring (rust + road grime may hide the separation near center) ... lt1 procedure --remove only the three bolts (similar to the sbc1) but do not remove the center bolt (as was reqd with the sbc1)...the three-leg casting slides off the hub when new, most ''experienced units'' req help from the HB puller (same tool as sbc1 but 5/16 -18 bolts for lt1 vs 3/8 bolts for sbc1)...note position of the huge ugly position indicator cast on the three-leg part between the three bolts for later re-install.

the pulley grooves are cut into the harmonic balancer, just one piece as you observed.

 

[Phill]

Better late then never i always say. check out the secound post on this thread.

http://corvetteactioncenter.com/forums/showthread.php?t=99212&highlight=OPTI+SPARK

 

[LT4man]

When I replaced my cap and rotor at the beginning of summer, I ran into a problem getting the pulley out of the engine bay. I needed about a 1/100th of an inch of clearance, which I did not have.

I had to take the two long bolts out of each engine mount and jack up the engine a small amount. The pulley came right out.

As similar as these frames & drivetrains are, you can have one sitting just a little bit different than another one.

SAVE THE

 

[Achilles]

I got the pulley off OK and now the opti-spark is off.

What a mess! The whole entire front of the motor is covered with oil and grime. I can't figure out where it's coming from though. The intake was R&R a few years ago and sealed with the "Right Stuff." So I doubt that is the source. I'm wondering if it could be the seal in the timing cover for the opti-spark. But I think that is unlikely since it wasn't too dirty behind the distributor. So that leaves the crank seal or the timing cover gasket. Not sure if I care to deal with that issue right now.

I ordered a new opti from All Ignition for $149.00. Hope it's legit.:W

 

[Toms007]

If I were you, I'd replace all three seals while I was in there and had the front torn down already. I bought the seals as a kit from someone on Ebay (about $30 delivered IIRC), I don't remember who....thepartsladi maybe. The only other thing you'll need to do the job will be the Kent-Moore crank hub puller, which I bought one, again off Ebay, but you can rent them from dealerships (as I understand).

 

[Achilles]

Got everything back together and the car started right up. I do have a small miss at idle though. Don't know if its a bad opti or not. I was a little suspect to buy an opti-spark for so cheap. But they claim its new and its garanteed for a year in case I have to return it.

I hate to tear everything back down.

I'm trying to figure out how to burp the cooling system too. I'll search the forum to see what I can find. But if anyone knows, please pass it along to me. I figure it should have something to do with the bleader on the thermostat housing.

Thanks