LT1 coil conversion

mustangmike6996

mustangmike6996

Club Member
I'm 99% sure the Optispark in my 93 vette took a crap again. What coil on plug options are there? The only thing that keeps popping up is the LTCC LS coil swap which is $300 for the module, plus wires and coils. Are there any cheaper or better options?
 
As far as the LTCC conversion, it still uses the opti for the cam position, so if the optical portion of your optispark went bad you will be in the same boat of having to buy a new optispark ontop of the module, wires and coils.

The EFI Connection 24x conversion has pretty much made the LTCC conversion obsolete. It is a bit more pricey at about $1600 or so, but for the price and peace of mind of never having an opti again it seems like a better option. You will need to run an LS1 PCM, but if you message EFI connections they will hook you up with all the necessary tech and hardware you will need.

93 has the non vented opti which seemed to be more problematic than the 95+ vented ones. You can convert to vented but by the time you get all the right pieces you will have pretty much the same amount of money into it as you would if you just did a 24x conversion, so that swap is kind of pointless. MSD opti's have a 50/50 reputation, I never ran one so I have no first hand experience, ive always replaced with an OEM opti but my LT1 never made huge amount of power.
 
Last edited:
I bought a 411 PCM at the junker in case i ever want to do that swap. Essentially, you install a distributor, cap and rotor and it eliminates the opti 100%. It is pretty well documented and a pinout diagram is online. I think there are some drawbacks, but as opti's become harder and harder to come by (I cannot find an OEM new opti), this may be the direction I go in the future.

I also believe that this PCM is more familiar for tuners. For the LT1, the only guy I know thats super solid is Moe Bailey and he may not do it forever.
 
I have been chipping away at the Vette. Following the factory service manual, it led me to the ICM (ignition control module). I decided to replace the ICM and coil at the same time, the AC Delco ICM was about $150, coil was around $40. Installed the parts, car fired right up, ran for a few minutes then suddenly died. I was in the driver seat and watched the tach immediately drop to 0 RPM before the car actually stalled. That lead me to focus on the Opti. During the diag, the service manual led me to the opti or the PCM. I spent a while looking for a OE replacement Opti, they are pretty much non-existent. I found OE reman units but they dont always have the good Mitsubishi optical sensor and they cost about $375. All of the other replacement units are junk and expensive (MSD being about $700). Hell, just the MSD cap and rotor are $220.

I ended up removing the opti to inspect for water leaks/moisture etc, I pulled the cap/rotor and the housing looked great. I posted on a LT1 forum, someone pointed me at an AIP brand sensor. I ordered the sensor for $60, figured it was worth a shot at this point.

In the mean time, I hooked up a 12vdc power supply and attached my oscilloscope to the low and hi res wires then spun the opti with my cordless drill to look for a good square wave from each side of the sensor. I see a somewhat distinct (but noisy) high res waveform. The low res waveform seems like its inconsistent but it is tough to tell. I plan to retest, with my o-scope tuned a little better and focus on the low res side.

The low or high res signal loss should have set a DTC. No DTCs are present (except #12 which is an OBD1 BIT check for the ECM in diag mode). It is possible that the opti failed fast enough that it wouldnt set a fault but most of the people who are seeing my symptoms are also finding a crusty opti unit from water/oil intrusion.

One random thought I had, which I am not sure about yet... Adding an old school coil to fire the opti distributor to get the car running temporarily. Im sure it would set faults, the PCM wouldnt be able to advance spark etc but in theory, is there a reason adding a standalone coil work???

So here are the options I see going forward

1- Replace the opti, car runs and everything is great. Replace opti sensors as-needed (no clue on longevity)

2- Use aftermarket components listed above, which are also recommended in some C4 forums/FB pages

3- Do an opti delete, pull the LT1 intake, maybe convert to a carb style intake/cam and use aftermarket fuel injection (I don't like this option)

4- LS swap. Very costly to fix the problem at hand but not too much more than some of the LS ignition swap kits. I would most likely try to swap in a manual transmission at the time, because, why not.
 
Last edited:
That Britney girl now works for Brian tooley racing. Could buy her ignition/conversion cause she is putting an a new LT in the car
 
Have you looked into doing a 24X Crankshaft Reluctor wheel conversion and run the LS computer & ignition? Don't know if that is still or ever was a legit common thing. Had a buddy do it home brew style almost 10 years ago.
 
1BADAIR said:
That Britney girl now works for Brian tooley racing. Could buy her ignition/conversion cause she is putting an a new LT in the car
Click to expand...

I looked her up and dont really see any info on what shes running (I have not tried to reach out to her for more info, yet).

CruisnCobra said:
Have you looked into doing a 24X Crankshaft Reluctor wheel conversion and run the LS computer & ignition? Don't know if that is still or ever was a legit common thing. Had a buddy do it home brew style almost 10 years ago.
Click to expand...

I looked at an aftermarket company's 24x setup (Torqhead) which is either $1500 or $2100 depending on which kit. There isnt a ton of info available (or I cant find it) because pics are missing from older forums or looking up the 24x conversion pretty much only brings up the torqhead kit.
 
My buddy Walt has a 95 TA and he is still running his original Opti on it, so I know they are not super reliable, but they will last for a bit. I guess how much work you want to do on this also depends on how many projects you have on your plate right now. Personally, I would just get another opti, because I have WAY too many projects on my plate that I am not working on. Maybe if you bought a reman from like Napa or somewhere respectable you could get a three year warranty at least?

It's not the lazy way out, you just get to spend more time actually enjoying it.

-Geoff
 
ultradriver10000 said:
The thing that sucks is you can grab a decent junk yard 5.3l and ecu for less than most of this crap to fix the Opti.
Click to expand...

That is is my hang-up with doing an Opti delete. I might just go for an LT1 delete lol.

WhiteHawk said:
My buddy Walt has a 95 TA and he is still running his original Opti on it, so I know they are not super reliable, but they will last for a bit. I guess how much work you want to do on this also depends on how many projects you have on your plate right now. Personally, I would just get another opti, because I have WAY too many projects on my plate that I am not working on. Maybe if you bought a reman from like Napa or somewhere respectable you could get a three year warranty at least?

It's not the lazy way out, you just get to spend more time actually enjoying it.

-Geoff
Click to expand...


I think that is the plan for the immediate future; its not lazy, it's pretty sensible. Ill put the new AIP sensor in, reinstall the opti and hopefully it will last a while. All of the optis (MSD, Accel, Cardone, Duralast, even AC Delco remans) are having quality issues on top of the normal opti issues.

Eventually I will probably LS swap it but I have a ton of projects happening all at the same time so the Vette has been on the backburner.
 
Last edited:
I just picked up a 1994 Roadmaster, super mint. I had to put an Opti in it, but if it goes bad again... its getting a nice 5.3/6.0L with an LSA on it lol.
 
I just installed the replacement Opti sensor and it's dead... No spark. Followed the factory manual again as a sanity check. It's completely missing the low resolution signal. It actually looks worse than the one I pulled off viewed on an oscilloscope. Waiting to hear back from the company about a replacement. I didn't install the water pump specifically for this reason. I wanted to install the opti, fire it up and make sure it ran first. So that's kinda good.

I was price shopping 5.3s a couple days ago. Then it got me thinking about swapping some 6.0 or 6.2s in the boat. I spiraled down a rabbit hole of considering a bulk purchase for 3 LSs lol. Damn hobbies
 
I just picked up an aluminum 5.3L ($200)... I'm going to toss bearings in it, toss a cam and some nice heads... get it ready to toss in the boat.
 
ultradriver10000 said:
I just picked up an aluminum 5.3L ($200)... I'm going to toss bearings in it, toss a cam and some nice heads... get it ready to toss in the boat.
Click to expand...

That's a pretty good score for $200. Most of the LSs Ive seen are $1200-1800 depending. I havent really actively been searching that hard though.



On a side note, I have been actively looking up 24x conversions. The Torqhead kit is for 1994 and newer (I have a 1993). I emailed them to see what the difference is and if there is any way to use it on the 1993.

I was really considering the EFI Connection 24x system (cheaper than the Torquehead kit but its a little more work to piece together). The EFI 24x setup breaks down to this:

24x Cam/crank sensor kit $450
LS PCM plus tune $200 from a different company, that is surprisingly less than I thought itd be
LS Coils $35 each (new) or about $80 for a junkyard set, Im sure I could find them even cheaper
LS Coil bracket adapter for LT1 valve covers with coils is $575 (way too expensive, Id probably make my own bracket)
Coil wire set $50 (estimate)
Conversion harness- Unsure, I might be able to repin my LT1 harness to the LS1 connectors and retrofit to skip an adapter harness, if an adapter harness is even available. Standalone LS harness is $650 (if most likely make my own conversion harness)
1996 timing cover w/CKP Sensor provision (super rare and expensive) EFI 24x has a new cover for $385
They also call for a single row timing chain, Im not sure if that means I can keep stock or have to swap that too.

So roughly, the cheapest 24x kit would be $1350 plus whatever incidentals I run into. Ill round up and say $1600 without a wiring harness.
 
ultradriver10000 said:
The thing that sucks is you can grab a decent junk yard 5.3l and ecu for less than most of this crap to fix the Opti.
Click to expand...

This! I started having issues with the opti in my Firebird and when I saw the cost of the LS coil setup I decided to just do the whole swap. Ended up selling my LT1 for more than the 5.3 cost me. had an iron block for a while and last spring found an aluminum 5.3 for $600 and put that in.
 
I sold a low mileage LT1 2 years ago for $1500, which shocked me... but yeah if you look around, I snagged a junk yard 6.0L with 2wd 4L80e and ecu and hardness for $400... high miles, but shoot, rebuilding it yourself and doing some performance and for say $1500 you'll have a great set up.

My Roadmaster has 70K miles on it... I might just sell the rig, but if I keep it around I'll sell the LT1 and just swap an LSx in it.
 
ultradriver10000 said:
I sold a low mileage LT1 2 years ago for $1500, which shocked me... but yeah if you look around, I snagged a junk yard 6.0L with 2wd 4L80e and ecu and hardness for $400... high miles, but shoot, rebuilding it yourself and doing some performance and for say $1500 you'll have a great set up.

My Roadmaster has 70K miles on it... I might just sell the rig, but if I keep it around I'll sell the LT1 and just swap an LSx in it.
Click to expand...

Where are you finding these lower priced LSs? I dont mind having to rebuild. A complete dropout engine/harness would be preferred.
 
You must log in or register to reply here.
Back
Top