SJW

If you have a good set of general mechanic's tools, and decent mechanical skills, you can tackle the Opti swap yourself. No special tools are required. Here are a few tech tips I wrote up some time ago about doing an Opti swap with new plug wires (HIGHLY recommended while you're doing the Opti, as it's a hideous job to replace the wires with everything fully assembled):

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Get a Factory Service Manual, and follow the procedure it lays out.

A few tips (I'm going from memory here, so I'll probably forget a few things):

Drain the cooling system.

Disconnect the MAF sensor and IAT sensor and remove the air intake duct with the MAF and IAT as an assembly.

Disconnect the ECT sensor and remove it from the water pump.

Remove the serpentine belt and tensioner.

You may find that you’ll need to unbolt the coil/ICM bracket from the front of the right cylinder head. I can’t recall for sure whether or not I did.

Unbolt (but don't remove) the power steering pump. This will help you to sneak the new plug wires in/out behind the pump, but may also be somewhat helpful when working on the water pump/Opti.

If you want more room to work, you can remove the radiator, but it isn't strictly necessary, and it involves considerably more work to remove it (I left mine in place).

The FSM will tell you that you need a special Kent-Moore puller to remove the crank pulley/damper. You don't. Here's how to get it off:

1. Raise the front of the vehicle enough that you can get under the car (it's also helpful to have it at a more comfortable height while you're working from above).

2. Remove the three bolts that secure the pulley/damper to the hub.

3. Mark the damper and hub so that you can easily see how to realign them to each other later.

4. Slide under the car with a long pry bar or hardwood dowel (I use a jumbo Snap-On screwdriver that's around two feet long) and a mallet.

5. Place the tip of the pry bar against the rear face of the damper, as close to the hub as possible (Ideally rest the tip alongside of the hub).

6 Give the pry bar a few whacks with the mallet, and with any luck the damper will pop off without too much of a fight.

You may find it helpful to apply a few whacks, then rotate the crankshaft in 120* increments, whacking it a few times at each interval (I haven't needed to do this).

It's also helpful to, if possible, shoot a bit of penetrating oil where the damper meets the hub, a day or more in advance of doing the job.

After you get the damper off, clean the damper/hub mating surfaces to remove all corrosion, etc, and apply a very thin coating of anti-seize compound to these surfaces before you reassemble the damper to the hub. This should make it a lot easier to get the damper off next time.

Once the damper is removed, rotate the crankshaft so that one wing of the damper hub is at the six-o'clock position. This will position the other two wings at around the ten- and two-o'clock positions. In this orientation, the Opti will clear the hub as it is being removed/installed.

The Opti basically unbolts and pulls off as you'd expect, once you have the water pump and damper out of the way.

Once the Opti is out of the way, inspect the shaft seals for the Opti, water pump, and crankshaft. If they show any signs of leakage, replace them now.

When you install the new Opti, be sure to align it correctly with the cam gear, and don't force it into place against the timing cover (do NOT use the bolts to draw it into place). At most, give it a gentle bump with the heel of your hand to encourage it to pop into place.

Reassemble everything else.

Follow the cooling system refill procedure in the FSM carefully, and you'll have no problems with this. In particular, be sure to bleed the air out of the system as it's being refilled. I recommend re-bleeding the system after each of the first three temperature cycles. I usually get a bit more air out by doing this. Be sure to pack rags under the bleeder screws before you open them, to catch the small amount of coolant that will leak out. You do NOT want coolant getting onto the brand new Opti!!! A cooling system pressure tester can dramatically speed up the bleeding process, if you own or can borrow one.

Hope this helps. Best of luck with it.

Live well,

SJW

BucfanTitan

Wow that was awsome.

I am going to look into getting a factory book. I have the hayes book and I find it to be very disappointing. They skip out on a lot of key items to complete the jobs.

Thank you for all the great tips. It means a lot!!!

mfi

And there you have it..I removed the front wheels which made working on it way easier..also jack it up high enough to really get under there for the damper removal.
As for putting the damper back on..I'm still researching the best way..DO NOT wack it back on, it must be pulled on..wacking it can damage the crank..
If you change the wires, I'm going to pull the wheel well covers on the drivers side as thats the hard one..hell anything you can pull to make things easier is a plus...

SJW

Always happy to help out when I can. Hope it proves to be useful to you. The factory service manual is worth the purchase price if you use it only once. The torque specs alone make it worthwhile, and it is invaluable if you'll be doing most of your own work.

An opti swap is a nuisance job, but nothing to be frightened of if you've done much wrenching and have a decent set of tools. It's just a bunch of bolts.

Live well,

SJW

SJW

If you clean up the damper and the hub that it mounts on (remove all corrosion - sandpaper works pretty well for this task), and apply a thin layer of anti-seize compound, you shouldn't have any trouble getting the damper back on. It should push on pretty easily by hand if the hub and damper are smooth and free of rust. Rotating it back and forth as you push it on will help, if necessary.

Changing the plug wires is not a fun job on LTx C4s, but it's a lot easier to do when you've already got the front end opened up to replace the opti. You'll never have better access. Here's a list of tips I wrote up some time ago about swapping the spark plugs and plug wires:

1. Raise the front end of the vehicle to a more comfortable working height.

2. Remove the inner fenderwell center panel on the driver's side. This will allow you to both see and do the job much more easily on the driver's side. You may also find it helpful to remove the wheel.

3. Unbolt the ASR bracketry from the frame, so that you can slide the ASR unit around to get it out of your way.

4. Remove the serpentine belt and tensioner.

5. Unbolt the power steering pump so that you can move it forward around a half inch. This will make it much easier to sneak the plug wires in/out behind the pump.

6. Use dielectric grease in the boots at both ends of the wires. Be sure to "burp" the air out of the boots after you get each of them pushed firmly into place, so that the trapped air doesn't try to push the wires off later.

Some guys report that they've had decent success accessing the Opti-end of the plug wires from underneath of the car, and that this saved them the trouble of removing the belt and tensioner. I haven't tried this, so I can't comment.

Take your time, work with care, and pay attention to what you're doing. The OEM replacement plug wires from your Chevy dealer are high quality parts, and will route (and fit into the wire looms) correctly. Run the new wires properly, and make sure they stay away from anything that moves, is sharp, or gets hot.

The passenger's side is not such a bad job. The driver's side is a Queen Royal Bitch (mostly because all of the belt-driven accessories are hanging on the driver’s side of the front of LT1/LT4 engines, and they leave little room for you to work or see what you’re doing). With plenty of patience, beer and Band-Aids, you'll get it done.

The spark plugs on the driver's side aren't so bad, when you've got things apart to do the wires. The passenger's side, however, is not so easy. The number 8 plug in particular can be a real headache, but with good tools and enough patience, you can get it done. Because there isn’t room for a ratchet on top of the spark plug socket, I use a plug socket that has a hex head on it so that it can be turned with an open end or box end wrench. It's useful to have more than one plug socket to choose from, as some will work better than others due to differences in length, wall thickness, etc.

Be sure to apply a small amount of anti-sieze compound to the threads of the new plugs before you install them so that they won’t seize in the cylinder heads in the future (this is especially important with aluminum heads). Just make sure none of the compound gets onto the electrodes or insulators of the plugs. I apply a very thin stripe of compound across the threads in one spot, and it spreads itself around the threads as I screw the plug into the hole. Also be careful that you don’t pick up any of the grunge that may have accumulated over the years around the spark plug hole in the cylinder head on the new plugs’ electrodes/insulators/threads while you’re installing them – try your best to get the tip of the plug straight into the hole on the first shot.

Live well,

SJW

mfi

Any one heard of these guys?

http://petrisenterprises.com/index.p...d=20&Itemid=26

radar502

I had the same prop. talked to lots of old school C-4 Corvetts racers and they said the same thing .Buy GM put an MSD cap seal the thing up with good sealer Ect. Not cheep but what is .. My 96 LT-4 is on the Dyno alot and sees 7,000rpm at times no big deal.. I wiil not put after market on mine or anybody else.. Good luck.. $135.. TOOOOO Cheep... Some things can be just too cheep... and the lifetime thing you'll be changing them for a lifetime...

mfi

The one from Petris is 399.00 and they claim its a real one.

radar502

Do what you like but GM is the only people that make THE REAL ONE.. It's the EYE that makes the thing work and GM has the best one they are the ones thet cane up with the thing.. If you buy cheep gona get cheep.. On some parts you just can't go cheep and if you evey change the thing out you will not want to go back and do it over ..We who have changed the thing out know PAIN IN THE A^& and water pump wires plugs ..Put on the best you can have the money for and hope for the best.. I changed mine out on my 95 yes A GM 5,000 miles cracked cap water inside DO OVER ..If you going to play with a Vett with an OPTI SPARK ask anybody need good luck ..They do PMS...

mfi

Well its arrived..but I won't see it until Sunday..problem is if I take it apart..I can't send it back...they claim its a real one...guess I'll find out when I do open it up to loctite the screws.....weirdest repair job I've EVER done...

cross3fire

Plus 1 for DELTEQ

1963SS

If you have the water pump off anyways, I always drill and tap the weep hole for a barb fitting. I then run a piece of clear aquarium hose from the fitting, away from the opti and end it at the frame and attach it there. That way if your water pump ever leaks the water will fall harmlessly to the ground and not on the expensive high voltage electrical thingys. It's real cheap insurance and virtually invisible.

Heckler45

Don't go cheap. If you do you won't leave home!

mfi

Yup...amazing how this thing is designed!

CAJUN C4

The OEM's have a Mitsubishi Sensor.Check out Item# 400216692869 on Fleebay.New OEM GM Performance Part Direct from AC Delco
$360.00 Shipped.

CAJUN C4

Very Wierd Job...Especially the Older I Get...Can't see as well or move around like I used to.Very tight quarters .My problem is I don't have a nearby Vette Savy shop I can trust.So,Me and my good friend tackles all this crap.Don't know what I'd do without Him.I don't know....just getting old I guess.My AC Delco is due in today.I'll post after we install it within the next week.Thank God I have a back up C4.

larry00

A good site for OPTI install including pics and making the needed tool !

http://www.impalasuperstore.com/nais...lace,with,pics

tjnjr

Just finished replacement of opti on my 92 C4. Used a NEW Cardone. Worked with Extreme care not wanting to do it again but guess what - the NEW Cardone (not supposed to be a reman) is defective and now the car does not run at all. This time a GM or MSD. Anyone else doing this job take my word for it don't go cheap on the opti and while the Cardone unit is not that cheap it is crap - new out of the box and supposedly fully tested - B.S. While the job was not terribly hard it is very time consuming and I really don't like the idea of doing it all over again. Thanks for nothing Cardone. The worst part is the car only has 26K miles on it and is always garage kept - the old opti internals looked like it was 100 years old - rusted and green.

active1951

was the old opti bad, no start condition?

tjnjr

active1951 - with the old opti the car idled rough and ran but no power under load and it had popping in exhaust. With the new opti it turns over and sputters but does not run. the old unit was badly rusted inside and all the cap plug wire pins inside the cap were badly corroded.
I took great care in reassembling the engine even put in a new water pump, gaskets, plugs and wires. Checked the plug wire placement 4 times thinking i might have crossed a few but everything is as it should be. the only thing i can think of is the cardone unit is bad. the car went from running lousy to not running at all. Any thoughts would be appreciated before i tear it all down again. the car has 26,000 miles and is never out in wet weather.