9T3VETTE

I've got the opti removed from my 93 while i'm doing some other work on the motor. Dealer paper work shows it was replaced in 2000 with part number 10457702, so i'd assume it a NOS AC Delco with Mitsubishi optical sensor??

Prior to removing, there have been no issues with it's performance so i'm hesitant to open it up or play with it, but now would be the best time to do so.

What do you guys think...add a vent, lock tight the rotor screw??

MatthewMiller

If it has the Mitsubishi sensor, then it may be worth reinstalling with a couple safeguards. What is the bearing like? When you spin it, is it fairly quiet and smooth? Any play in it? If so, then it may be worth replacing the opti. This tends to be a problem with high-rpm use more than normal street driven cars.

If the bearing seems good and the sensor is a real Mitsubishi part, then I would be inclined to do a the following things and then put it back in. I would probably put Loctite blue on the rotor screws. I would also inspect the cap and rotor for wear and oxidation, and replace if they don't look good. Finally, I would seal the cap and middle plate to the distributor base (the two areas sealed with an o-ring) with RTV and put silicone grease on the rubber gasket where the sensor harness passes through the cap. This should help keep water out.

Tom400CFI

I'd add that if it seems serviceable (the bearing is still good), then I would get a grease needle such as this:



Slip it into the bearing's seal and pump some fresh, quality synthetic grease in there. Kept greased, the bearing should last quite a long time.


Last, if the inside of the unit dirty inside (and they usually are) with dust/soot like matter then I would clean it out and clean out the optical unit w/a tissue paper and windex.


.

jay23ls

So that's what the infamous faulti-spark looks like! Never seen one removed.

This might be a dumb question but is there any preventative maintenance that can be done when its not dis-attached? Sorry if too off topic

9T3VETTE

The bearing seems to be in good shape as it spins smoothly with no play. I don't have the correct bit to open it up yet, but should be able to do that next week.

If it does have a Mitsubishi sensor, should I order a new cap/rotor that is vented? Something like this MSD unit..

https://m.summitracing.com/parts/msd...FQEDaQodknkI6g

cardo0

I'm not sure if the MSD cap and rotor kit fits the AC Delco/OEM Opti. They maybe for MSD Opti only.

You should be able to see a measurable amount of deterioration on the brass terminals and rotor tip if it needs replacement. If it cleans up with a cloth then it should be ready a longer life as is.
A proactive maintenance would be convert to a vented system. Super Chevy has article on doing this and performed by Petris automotive. It looks like a lot of work though - be ready.

My feeling is if it ain't broke don't try an fix it. Well in your case you have a good opti in hand. You didn't post how many miles are on it but it was new in 2000.


Normally this would be a chance to experiment and try something else as you now have a working backup. Those AIP opti's sold by Sac City are tempting to try as they claim an improved sensor that's better than Mitsubishi spec. And are dirt cheap!
Sorry but trial and error is the only option here as so many internet posts are unreliable. To many owners manage to goof up their Opti just putting in on and blame the mfr.

Now if you are making major engine modifications it's best to stick with what you have working at least until the engine is cooperating well enough. I would leave experiments for later. Only one I would consider now with the Opti out is the conversion to vented using that same Opti and replacing the cap/rotor in the process.

Good luck

1993C4LT1

Are you putting a cam in the Ruby?

9T3VETTE

You make some excellent points that also crossed my mind. Service records shows the car had 68,883 miles when it was replaced and now has right about 91k on it. So, it's only got about 20k on th unit which isn't much.

I also saw the super chevy article about converting and you are
Right that's a lot of work to add a vent!

My gut feeling also says if it isn't broke, don't mess with it. Never know what kind of additional problems could be created by getting into it. Like you said with a larger project on hand at the moment, less variables for issues at startup is probably better.

Yup. Nothing radical, just a GMPP hotcam kit. Many argue it's old technology (which it is) but it's a proven performer for what I'm looking for. Should be fun!

1993C4LT1

​​​​​​​Niiice But yeah, cardo pretty much told you what I would. But yes, I would for sure RTV the part where the o ring goes on the opti. Dumb question, if we were to put that cam in, would it require any bottom end strengthening?

9T3VETTE

its my understanding people RTV the internal cap to housing seal of the unit. This is what your talking about?

As far as the cam you should be fine as long as your starting with a well maintained platform. Upgrade the valve train to suit the cam and don't rev the hell out of it and you should be alright.

1993C4LT1

Yes that is exactly what I mean. And nice! You should make pretty good power with the cam and longtubes! Can't wait to hear it!

MatthewMiller

There are two seals that can take RTV here. The cap doesn't seat directly on the cast opti housing. The cap seals to a plastic "intermediate" plate. That plate then seals to the cast housing. Both interfaces can take a thin coat of RTV.

cardo0

IIRC the connector to the wiring harness looked like a possible location for leakage. I use generous RTV to seal around that connector.

With the non-vented Opti you don't have the issue of the lower pressure of a vacuum drawing air and contamination into the Opti. But there are self sealing electrical tape (mastic ?) available to give the entire Opti pancake a "wrap" around the edge - just an idea here.

Good luck.

9T3VETTE

Thanks guys. Ultimately think I'm going to run a bead of RTV around the outside of the housing and around the connector. It's working for now so opening up may not be the best idea.
The mastic tape is a good idea as well. At work I often use dielectric tape that creates some electric insulation, might be a good product to use for this.