Formula350

iTrader: (3)

So me and my friend were discussing the LT1 over dinner and how it's a great motor, but nothing either of us would really want to go through due to the opti.

I've brought up the Vortec distributor(crab cap) before and it has a built in cam sensor. And the debate on it before was that we still would need the Opti for the crank sensor. What about the years that have their own crank sensor? What would stop anyone from rewiring the cam sensor to the Vortec distributor? And then continuing to use the crank sensor?

Also, from the last thread I want to make sure I understand the difference, and their use. The cam sensor is for the injectors and crank sensor is for the spark correct?

Also, would a Vortec timing cover work on an LT1? If so, and we wanted to fully ditch the Opti, it has a crank sensor, so all we'd have to do, is use the crank sensor sprocket from a Vortec motor right? They are only 4 tooth from what I remember (we just pulled a Vortec shorblock apart). That would eliminate having to fab a opti cover for the current timing covers, and would be a simple upgrade for the non-crank sensor timing cover LT1s.

Aside from that, the Vortec motors use the exact same coil and ignition control modules, they're just not located on the head like out LT1, but next to the throttle body like the TBI motors.

I know the Opti isn't all that bad, but just getting rid of it from the front of the motor just would seem really nice. And the crab cap I believe would fit all under the back of the intake. And even if you wanted to run DIS, you could still probably use the crab cap and eliminate all but the cam sensor on it.

If this comes across a bit confusing, let me know what part you're stuck on and I'll try and further explain what I'm talking about.

fergymoto

iTrader: (129)

The crank sensor is for nothing but misfire diagnostics. Pre-1996 models don't even have one. I also think it would be about impossible to R&R a distributor of any kind on a 4th gen F body with a LT1 intake manifold plenum in the way.

Formula350

iTrader: (3)

Well aside from the cowl, places mod the intakes to accept distributors, so apparently there is enough room for one. I don't see how this would be any different.

Revelation Z28

iTrader: (10)

in your theory, using a CMP sensor for a crab dist, we could also re wire it to use LS1 coils just like gen III uses.. but thats been talked about i bet and no go.

Formula350

iTrader: (3)

For or From? The Crap Cap distributors have a CMP implemented inside them.

TwoFast4Lv

iTrader: (8)

Last i checked it will not deliver the signal we need, Sorry.

Formula350

iTrader: (3)

OK Vortec setup aside. Couldn't you technically use a SD TPI rig up on a SD LT1 (minus opti with the appropriate distributor)?

Paul Bell

iTrader: (9)

Looking very carefully at the distributor guts, the opti pickup actually has two sensors. One for low resolution pulses and one for high resolution pulses. The PCM needs both to precisely tell where the crank is. There is no other distributor that’ll do this. I’ve seen here a picture of a rear/intake manifold mount distributor that has been modified with the opti pickup and wheel.

Formula350

iTrader: (3)

Hell if I was going that far, I'd just try and cram all the guts inside a normal distributor and then run coil packs

Paul Bell

iTrader: (9)

Here's a pretty good description of everything about the optispark system:

http://www.carprogrammer.com/Z28/How...%20better.html

And here's a pic of the wheel. Notice the four low resolution slots are different sizes so the PCM knows when each cylinder needs to get fuel and spark. The 360 high resolution slots make it presise. This is how the system has sequentional fuel injection, not batch fire like the older TPI engines. That's right guys, it controls the fuel timing also. The LT1 PCM must have the optispark distributor in use and can't be replaced with a different pickup type.

Formula350

iTrader: (3)

Yes, but, 93 ARE Batch Fire SD systems. Which is why I asked about a TPI wiring + ECM(calibrated VE tables and such) on an 92-93 LT1.

Paul Bell

iTrader: (9)

I see it now, you mentioned using the TPI setup in your fourth post. I suppose it would run, a V8 is a V8 but you would lose many of the advantages the LT1 has over the TPI.

I think the crab distributer will fit under the cowl but man, what a bitch it’ll be to get at.

I’d love to see how this works out, keep us posted.

Awake455

What's the reliability like of the kits like the LTCC (LT1 to LS1 coil conversion) package offered by Bailey Engineering (that graft coil packs onto the LT1/LT4)? IIRC, they reduce the opti's chores to that of a sensor. No more possibility of the high voltage spark side shorting out the low voltage sensor side. The speculation when it came out was that the opti would last much longer. Any real world results?

BoostedZ28

The results of the LTCC and Delteq systems have both been great. I ran the LTCC system for some time before switching to a BS-3 system and truely enjoyed it as well as experiencing zero problems. As mentioned above, the most persistant problem with the Opti-spark distributor is in the high voltage portion of the system. Once it has been removed, most of the typical Opti problems are non-existent. The optical wheel and sensor that produce the high and low resolution pulses that the PCM requires for fuel and timing are fairly reliable and don't usually fail.

It would seem to me that if someone is interested in "upgrading" their LT-1 engine management system, you might consider installing a 24x crank trigger and cam sensor and switch to an LS-x pcm (along with the necessary wiring as well). I don't know if anyone has done this using a factory LS-x pcm, but I am running a Big Stuff-3 LS-x system on my LT-1. I have completely eliminated the Opti-spark distributor and use 8 coils.

Formula350

iTrader: (3)

Well I knew about the Coil Pack conversions using just the sensor portion of the Opti and making it much more reliable, but using the LSx system is pretty interesting.

Paul, sadly, I myself don't have the resources or money to do such a mod. I made this thread in hopes that someone with the time, know-how, and spare parts could do something like this.

I'm still curious if the Vortec timing cover would fit on an LT1 though.

TwoFast4Lv

iTrader: (8)

Might want to see what The fast Stock PCM guys are running

Opti's

For some reason the LTCC and Delteq have Issues staying sync'd up in some cars. PEPE's car and Mine were a few of them.

96lt1m6

iTrader: (31)

i believe Taner has the crab style dist. in his car
as far as it being difficult to get to,how often will you need to mess with it???


the vortec L31 timing cover is not compatible with the Lt1
you would need the 96/97 Lt1 cover to have the CPS

socal

iTrader: (1)

i have the ltcc kit and it was the best invesyment ever but i have heard of someone stuffing the opti guts in a reguler sbc distributer and gm makes a plug for the 95+ vented opti cover

Formula350

iTrader: (3)

I figured it couldn't be too difficult to do. Either all, or just the sensor bit.

taner

iTrader: (6)

i hae been running the crabcap GM dist. since last year, i love it! it is a bit of an art to get it into the car with the intake at the same time, but worth the effort!

hope that helps. but i am also running the XFI in my car as well, which i love!!!!