I did a search and found a lot of "should I replace my opti with a Dynaspark or an LTCC" posts, but nothing that has the detail I'm looking for. I have a high RPM (~7200) LT1 track car that needs a more robust ignition system, I've been researching as many options as I can find. Can someone who has this system (or knows it well) help me out?

I would like to know exactly how the LTCC works. My basic understanding:

Leave optical portion of Opti installed. Connect it to the LTCC computer. Buy LS1 coils. Run wires from LS1 coils to spark plug.

Here is what I need to know:

1. How does it interface to the Opti? Do you take it apart and leave the little metal disc exposed? Do you open it up and take out the rotor and use the stock opti connector?

2. How does it interface with the ECM? Through the standard harness?

3. Can the ECM still moniter and retard spark?

4. Do I need to have some custom spark plug wires cut?

5. Is there timing adjustment, and if so, how much?

6. If I'm using the optical part of my opti, does it matter if it's my '93 style or do I have to get the updated version? I assume I can keep the interface to the cam that I have.

7. Is there a way to use a crank position sensor instead of the opti? I'd like to have a simpler system if possible...I suppose I'd have to bypass the ECM in this case, though.

Thanks to all.

 

I'm using the LTCC on my '93.

I don't think I can honestly answer all yoru questions since I had ehlp with teh install, but here's what I did.

The LTCC comes with a wiring harness, it plugs in to a plug that runs alongside the intake. Then there are two other wires that get hooked up somewhere in the ignition module area. You will need custom wires I used the ones that were listed on Bailey's site and they are about an inch too short.

I didn't even touch my opti, it's still the original one intact with 44,000 miles on it.

I believe there was someone who used a crank trigger set up on theirs.

There is a timing adjustment inside the black box.

 

Ok, that's the plug for the Optispark. Sounds like it just plugs into the current opti. Do you replace the stock ignition module with the LTCC box, or do they work together?

Hmmm. I think my Opti timing may be part of my problem. I may have to take it all apart, anyway.

Do you remember who? This is what I'd like to do if possible.

Any idea how much adjustment?

Thanks Mojo!

 

I don't remember how much adjustment. The stock module is no longer used.

 

I will try... I have the LTCC on my 1992... and when installing it, I did a ton of reading about the unit...

No. The opti stays put. You can, and with a 7200 RPM motor I would, remove the opti and remove the rotor button. The LTCC comes with an interface that connects at the diagnostics port. The LTCC brain intercepts the signals so it can then fire the appropriate coil.

It really doesn't. It's more of a piggyback.

Yes.

Yes. I made my own Taylors.

Not really. You can set retardation and override the limiter... how this works I am not entirely clear.

No. The LTCC will work with any opti.

No. This system requires the opti to stay. If you want to go that route, you will have to get a full blown standalone ignition system.

I found it... A couple of years ago, I re-wrote the LTCC manual for Bob. I gave him the document a while ago and I donno if he is using it, but, this is what I came up with... it should help. I think this is the final version... I hope it is....

LTCC Revised Installation Manual

 

Bogus - Great, I was hoping you'd show up. I've seen you here and there on these threads and knew you had the system...

Hmmm. Then I'm not sure it's what I need. It's going to get me better spark, a more robust system, and allow me to rev higher, but not fix the timing problem I have now. Probably still worth doing, though.

So it doesn't actually replace the wires at the diagnostic plug, it simply splices in to grab the two optical signals coming into the ECM at that point?

Magnecor is just up the street from me, I'll give them the lengths and have them cut me a nice set of 9 or 10mm wires

Do you have the correct lengths handy? I assume yours would be the same as mine, even though I have a year newer car.

Hmm. I'll have to contact Alvin and see how this would work with my chip. He already moved my rev limiter, I guess I'd just set it high in the LTCC and let the PROM do the limiting. Also, it seems risky to mess with the retardation, like you could end up having the LTCC fighting with the ECM and end with cracked pistons.

Well, that's half good news. Although I think I'm going to pull the opti off to check the pin alignment, anyway. So can I pull the rotor out of there and only leave the disc and optical pick up, then put the cap back on to seal it?

If I can find this method (without needing a whole new computer) I'm going to use it. Otherwise LTCC my solution.

That's very helpful, thanks. What did you do for the coil brackets?

Also, what all do you remove from the stock ignition system, just the coil and ignition module?

Thanks again.

 

The LTCC module has a setting that lets the ECM set the rev limiter... so I would not fret that.

I will put a measure to the wires, but they are a little longer than the stock LSx wire, because the coils are farther away. I would guess about 12" or so.

I made brackets from some metal rods. If you want, I have the LSx coil brackets... I can forward them on.

You can remove the rotor and reinstall without. I would seal the cap to the body with RTV, tho. Use Copper... it will tolerate the heat and chemicals better.

I removed the coil and module... they were toast.

This system should hold you to 7200 RPM. Think about it - LPE gets that many RPMs from a modified LSx motor and keeps the factory coil.

 

We're tearing into the car again today, it was supposed to be warm but it looks like the torpedo heater will be in full force. I need to see where the timing is since I can't figure out how to get my laptop to interface with the ECM. We'll be going old school, measuring by putting timing tape on the crank and using a light. It'll feel like an old street rod...

If the timing's off then that most likely means that I have the Opti drive pin in a tooth off again (happened once before, it's gotten pretty worn. Time for a new pin.). If that's the case then I'll remove the rotor when I pull the Opti off to align it. As much work as that is, I really hope that's the problem. At least I know how to fix it. I sealed it up with black ATV when I installed it the last time.

Anyway, once I determine if the timing is off I'll know where to go next. Most likely that will involves an upgraded ignition. Or, as I said above, it probably makes sense to just do it, anyway. What bracket do you have, the one shown on Bob's website? Why didn't you use it on your car? I'm fairly handy with fabrication so I'll take a look and see what's easiest.

Thanks again for the help. I'll PM you in a day or so to let you know if I need the measurements and brackets.

 

I used the factory brackets, but I made my own cause I had the time... boredom set in, I guess...

Keep me posted on your progress!!!

 

heres my setup:




mounting of my control box:


PS..good job Andy on updating Bob's manual.

 

thanks! I donno if Bob has ever published it...

I love where you put the box! Do you have any heat related issues with it there?

I may have to remove mine if the smog dude gets cranky next time... the last time it was ok, he ignored it.

 

I haven't had any heat related issues or any other problems with the system but I do plan on fabricating a heat shield and possibly adding finned heat sinks to the box just to be on the safe side.

 

I didnt read the whole thread but FYI...
The LTCC still requires the use of the optical sensor in the distributor, reliability is still an issue in regards to the poor design of the OEM distributor even when using an LTCC system.
We are working on designing a rotorless cap system (Gen III) to be used with the LTCC that will give you the best of both worlds. More information to come in the future, just something to consider for now.
Sincerely - the distributor guy

 

I am fully aware of the limitations of the original opti... it's junk... especially the Gen I units.

However, once the high voltage has been removed, the unit will last, if kept dry, a lot longer!

Just don't get coolant on it!!!

I will be looking forward to the capless dynaspark!

 

99, thanks for the pics. One question - where is your oil filler cap? I looked for it on the side not shown on the top pic but couldn't quite make it out.

I have a filler cap on one side (passenger) and a vent stack on the other (driver). I'd have to do something to mount the coils around those.

Not the best pic, but one I already had saved...

 

BTW, results of tonight's investigation here:

http://forums.corvetteforum.com/show...post1554072348

Not really LTCC related so I started new thread.

I'm going to upgrade, but want to get the car running normally again before adding the LTCC...hopefully that will happen next week.

 

Rotorless, and we use a billet cap, /w a few other secret goodies, more info to come

 

oh, yea, rotorless.

 

following

 

I doubt it , no action in over seven years

02-20-2006