LT1 optispark Usage
 

Is it possible to use the LT1 optispark without the engine computer and just a aftermarket ignition like MSD or mallory?

I have a 91 Mazda RX7 i am droping a SBC 350 in and the space for the distributor is very limmited, was wondering if this would be a decent option, cause I can get the complete setup fairly cheap.

:think: I'm going with negative.

haha

hehe

:think::p

Well I am glad you all are haveing a laugh over this.
but have you actualy stoped and thought about it?

would it really be so hard to do?
From what I have found it is very simular to the mallory unilite distributor both use a optical sensor for signal.
I would think it would just be a matter of supplying power and feeding the signal.
Now for the tricky part. How would you ajust the timeing?
think I found my answer in the summit catalog.
msd part#MSD-8680
Allows you to ajust your timeing up to 15 degrees.

Now I came up with that while tossing and turning in my bed trying to goto sleep.
Now its time for some research.

Any "REAL" input would be apreciated

Just curious... if you aren't using the stock LT1 PCM, how are you running the fuel injection? It would seem that using the stock PCM for both ignition and injection would be the easiest and lowest cost approach.

When you say "a aftermarket ignition like MSD or mallory?", what exactly do you have in mind? The MSD CPC system would be a killer arrangement, and does not even need the Opti.

Most people try and get rid of the Opti, and that is very easy to do if you don't intend to run the stock PCM. By eliminating the stock PCM, you are eliminating the "processor" that takes the pulse signals from the Opti, translates them to cam and crank position signals and then looks up the spark timing in the maps and sends the "fire" signal to the IC Module. You would need to develop a translator for the Opti pulse signal, and an electonic spark map, and a "driver" to provide the "fire" output. This can be done with several aftermarket ECU's, but that would be a lot more costly than simply using the stock system.

The MSD 8680 is an "add-on" for an MSD-6 or -7 box. It can run from an external signal, but it requires a magnetic sensor input. The Opti doesn't provide this. You could alter "initial" timing with this box, but you certainly couldn't twist the dash mounted know fast enough to simulate a real timing map.

I guess I just don't understand what you are trying to accomplish.

I'm not running fuel injection. its carbed.
I'm just looking at this as an option because of the limmited space for the distributor.
its seems like it might be feasable but it looks like the cost is going to be too high.
I was just reading up on how the sensors work and that there are actually 2 diffrent ones that provide the signal for the cumputer, one speed sensor and one crank possition seneor.
but I allso read about a company replaceing those with a hal effect sensor to act as a makeshift crank trigger witch shows some promise.

There is only one optical "sensor" in the Optispark.... a rotating disc with two rows of slots, one with 360-slot for 2-deg crank position accuracy, and another row with 8 variable width slots that allow the PCM to know exactly which injector to fire.... in effect the cam position sensor. There are two light emitters and two receptors.

If you are not running fuel injection, its really very simple. Get an Electromotive HPX "lost spark" system, utilizing a simple magnetic crank position sensor, spark timing controller and 4-coil pack. All you need to do is bolt an Electromotive 60-tooth crank wheel on the front of the damper, add a magnetic pickup, and feed the crank position to the controller. The controller includes a 3 dial setup that allows you to set initial timing, ramp up timing advance slope to 3,000rpm and ramp down timing advance from 3,000rpm to redline. Pretty much what a simple distributor with centrifugal advance will provide.

If you want more sophisticated spark maps (rpm and MAP based), look at the MSD CPC (coil-per-cylinder) system. That system uses a distributor "stub".... essentially just a shaft, in place of where the conventional distributor would mount (no height problems, its flush), a timing computer and 8 individual direct fire coils.

Electromotive HPX

MSD CPC System

you know the HPS system looks great but I'll be damned if I can find a single one of the websites they have listed that actually has a listing of that ignition system, allthough i did find one for a 4 cyl for 600 bucks.

The MSD system once you buy all the pieces for it is well over 1000.00

I'll argue with you about the sensor thing later...:D

not to mention the opit only works on an lt1/lt4 block.

LOL thats the easy part to get around.
its not the block that makes it special, but the cam gears, cover and other extrernal to the block pieces.

I'm not even remotly worried about that.

well i would like to know how you are going to do it.

Cam - no problem
timing gear - ahh iffy
timing cover - ??? Good luck.

Why not just go with a front drive distributer instead of an opti crap anyway

just my 02 cents

wel my first thought (hope) was that i could do it fairly cheaply.
but that is turning out not to be the case.

the parts I would need to set all this up are all over ebay right now, and not to badly priced i might add Includeing the timeing cover.

As for the front drive distributor, well cause I'm an idiot and forgot all about those damn things till now..lol

Summit stoped listing them in the catalogs, but I just found one in the jeggs.
Thanks for the reminder.
:metal: :thumb:

glad I could help.


I didn't know about those kits. Sounds cool.

I'm looking at the picture of the one in the jeggs book. it looks like it mounts above the timeing cover, is that correct? So i am asumeing it would clear even a stock water pump.

Do you know anyone that is running one of these or where i might be able to see a pic with one installed?