I know that the Opti spark has been cussed and discussed at quite some length and I did a search on this and didn't find anything.

I have a "bone stock" '93 coupe with an LT1/Auto and I believe that Opti spark is going south as is the water pump. I know that the stock Opti for my vette is P/N 10457702 but that is the non-vented. I'd like to install the vented Opti and would like that part number. I'd also like the MSD part number too - in case I find one of those at a price I can afford.

Thanks in advance for your help.

 

The GM and AC Delco number of the vented Opti is 1104032, but it comes up as discontinued on GMPD so it may have been superseded. The MSD number is 83811.
Keep in mind you will also need to change the timing cover and adjust the cam drive pin to use the later style distributor. The timing cover number is 12552426.

 

The MSD part number for 92-early 94 is 8381 (83811 is for late 94-96). Contact epowershops.com for a quote - you'll be ordering the MSD

 

Toptechx6 and Pianoguy - THANKS - appreciate the P/N info.

I "was thinking" I'd like to put the later model vented unit in - but it doesn't sound like it's a direct "bolt-on" with the info that you shared about the cam drive pin and cover. I couold get by with the direct replacement stock unit if they last about 60,000 miles. I don't think I'll own the Vette that long that I'll be seeing 120,000.

I was looking at parts on "that auction site" thinking I could go that way. I wanted to know the P/N's so that I could use them in a cross check to insure I was getting the correct parts. The "return" policy on some of the "sellers" is "hit and miss" and I don't want to get "stuck" with an Opti that won't work.

Forgot - going to need the water pump also. Guess I don't know what that number is either.

Is there a thread that goes through a step-by-step of an Opti change out?

 

thepartsladi on ebay will likely have the best price on your water pump - just search for that store name, then search for lt1 water pump once you get there.

There are tons of threads about the opti procedure. From memory:

1). Drain the cooling system, by opening the petcock on the radiator, and then by removing the knock sensors on each side of the engine block
1a). Disconnect the battery negative cable
2). Remove the air cleaner bellows and serpentine belt, disconnect electrical connections to MAF and water level sensor
3). Disconnect radiator and heater hoses, and remove the water pump (you may also want to remove the radiator hoses to get them out of the way)
4). Remove the harmonic balancer pulley (3 bolts) - you may want to spray some PB blaster where it mates to the hub, and also mark the pulley's position. Note that the pulley bolts must be roughly at 10, 2 and 6 o'clock in order for the opti to clear the hub.
5). Mark the spark plug wires and vacuum hoses, and disconnect from the opti
6). Remove the cap from the opti and mark the location of the rotor
7). Remove the opti
8). Check the seals around the opti and water pump drives, replace if necessary, and clean the water pump mounting surface.
9). Install new opti, noting rotor location - make sure it mates easily with the front cover without force
9a). After plug wires, etc. are attached to new opti, install the balancer pulley, connect battery and start the car briefly to make sure opti is functioning properly
10). Reinstall everything in reverse order - note - check the o-ring on the engine shaft for the water pump to see if it needs replacing. A new water pump will come with one o-ring for the pump, so you may need to buy another.
11). Make sure to bleed air from cooling system when refilling.

You may find that removing the belt tensioner and the coil gives you a little more room to work. Also, this is the optimal time to replace the plug wires - you will find that loosening the power steering pump to allow you to pull it forward a bit is helpful.

 

Pianoguy!!

Thanks - gives me a good idea what I'm up against. Sounds a little "heavier" than what the average "yo-yo" can do in a garage if you're not mechanicaly inclined and don't have a fair selection of tools.

 

I'm a pretty average yo-yo myself - haven't done much wrenching on cars for about 30 years. But I enjoyed this project - I did it while the snow was still flying, so it was nice to be able to take my time and clean everything up. It doesn't require much in the way of special tools - SAE and metric wrenches and sockets, some wobbly extensions, and an E4 Torx bit for the opti cap screws (the MSD opti comes with a little tool for removing the factory opti screws). I also used a large breaker bar and socket to hold the center bolt of the hub to keep it still while I loosened the balancer pulley bolts. The balancer pulley can be a bear - I tapped on it from behind using a piece of 2x2 and a dead-blow hammer to get it loose. Here's a few pics I took along the way:

http://bradprestonmusic.com/Photos/V...008/index.html

 

Pianoguy,

Thanks for the photo's - excellent job, I must say . . . the photo's AND the swap out.

Well - gonna' give this swap out a try - working on getting it to a friends house (another C4 owner) and will "do the deed" there. Have to get the parts shipped in yet so it won't be for another week or so.

I'll try to remember to "post up" the results.

BTW - the "average yo-yo" I was referring earlier was, of course, me.

 

Thanks much! Best of luck - if you run into any problems, I'm sure you'll find all the help you need here. I had read so much about the procedure here before I started that there weren't any real surprises. Get yourself a box of blue nitrile gloves, too (about $10 for a box of 100) - they'll save your hands a lot of grief.

 

Pianoguy and toptechx6 . . .

THANKS!! You guys are the best!!

Appreciate it very much. Getting the parts and I have a friend (C4 - ZR1) that's going to help me dig into it.

With what you wrote and sent, I think we got it covered.

 

No problem - that's the great thing about a site like this, lots of folks have been through exactly what you're going to do. Search around for more threads on removing the balancer (make sure to put some anti-seize on the mating surfaces before reinstalling), bleeding the cooling system, replacing the water pump, etc. and you should be able to visualize everything before you start. You'll learn a great deal about your car and be proud of what you accomplished!