twichy2011

Well guys, after some help from TorchTarga94, Bob Bailey, and PLRX, I finally finished my LTCC project. In all I probably put in about 15 hours of work (mostly spent trying to find the best mounting location of the "brain") Like many said, the job wasn't too difficult. The only skills that may be tested are your soldering and heat-shrinking skills.

So, I spent $399.00 on the LTCC kit from Bob Bailey, $180.00 on 2 mounting brackets D514A from EFI Connections and $20.00 on the screw to mount the brackets to the valve covers (replaced the old valve cover screws), $92.72 for 8 LS3 coils from Rock Auto, $91.58 for 2 LS3 coil harnesses, $107.89 for a new WPS optispark (hopefully I get luck with a cheap one since there is no high voltage running through the cap).

The entire setup set me back a whopping $891.19. Could have been a lot more, and had potential to be a lot less if I didn't have to buy a new optispark and if I made my own brackets to mount the coils.

As far as the install went, the instructions that were supplied with the unit were very descriptive and helped with the install. The only thing that was a bit vague was the Tach Filter connection that had to be made... I'll get into that later.

Here is what my coil brackets look like with the coils mounted.

Drivers side:



Passenger side:



Wire Hook-ups:

I tried my best to show a picture of the connections I made, but I'll describe them too. On a 1992 Corvette, there are 3 connections that need to be hand made(other than grounding coils and box), the rest is plug and play. The first connection is power to the LTCC box.

This consists of connection the two red wires from the LTCC harness to the pink/black wire that drove the coil. (Note: there are two pink/black wires that drove the coil, but only one of them is 12V with key on. If I recall I think it is the pink/black wire on the black connector.)

The second connection to be made is the EST connection which is pin B (white wire from the old ignition control module connector.)

The third connection is the Tach Filter. This one I found was a little difficult because the instructions didn't say much about it, or I just failed to read that part. On the tach filter there are three wires. One black and two white wires. The white/black wire from the LTCC harness connects to the outside white wire that is connected to the tach filter.

Grounds:

There are three grounds that need to be made. Two grounds for the coils (one for each bank) and one for the "brain". I grounded the coils to the fuel rail. The "brain" is grounded in the same place the horn is grounded. This can be seen in the last picture.


Mounting location of the LTCC "brain":



I mounted the box right in front of the coolant reservoir tank and uses heavy duty gorilla double sided tape to mount the box to the car.

I haven't had a chance to put miles on the system yet, but the car seems to idle smoother and may pull a little harder, but in my case that may be due to the failing MSD optispark that was on it before.

One last thing to note, when running the wires to the odd bank for the coil harness, becareful that the harness doesn't interfere with the throttle cable. That happened to me and caused the car to idle at 4500 RPM I thought I had a huge vacuum leak but turned out to be something really simple... whew. Overall the job was not too difficult to do. Also, LS3 style coils will work, but with a little extra work. The coil on the number 5 cylinder needs to be lifted so it will clear enough to connect the coil to the harness. this can be done with two or three washers.

Hope this helps with any question anyone may have. Also I'll provide updates as time goes on to let y'all know how the car is after I put miles on the LTCC system.

DMITTZ

Cool project! Thank you for sharing and hats off to you for taking this on and finishing it successfully.

PLRX

Well done!!

1993C4LT1

I still don't get the tach signal. Hopefully I finish my car today.

twichy2011

Where are you trying to get your tach signal from? I had trouble with that too. If you look at the tach filter there is a black wire on the outside, a bigger white wire in the middle and a smaller white wire on the outside. You want to splice in to the outside white wire on the tach filter

Hope this helps!

Connor

1993C4LT1

​​​​​​​I got it Connor, thanks a lot! You got me worried about the LTCC wiring getting stuck on throttle blade. I still need to build something to cover the brain box. To protect it from water.

twichy2011

I just ran the harness under the alternator bracket and that which held it well. The box is sealed, but better safe than sorry. I still need to cover my module as well. Glad you got it working!!!!

Connor

drcook

I have a couple questions that some might consider elementary, but I have only been in the C4 world since July 2016.

1. what type of valve covers does a 1992 have ? I have a '96. The reason I ask is because of the verbiage on EFI's site that talks about the composite valve covers.

per their website:

2. which bolt(s) and pieces did you use (not the bracket, you detailed that).

I am getting ready to buy the LTCC box myself. I have my coils and just need to finalize the attachment. I really like the way EFI's brackets look once installed and need to determine all the parts I really need to acquire.

Thanks..............

twichy2011

My valve covers are not the composite. I think they're like magnesium. I think they changed to the composite covers in 93. Not sure about that. The bolts that I used were from EFI Connections also. The EFI part number is 120-00027. The bolt kit was the only thing I needed to mount the coil brackets to the valve cover. I think what EFI is saying is that you can't use the stock valve cover bolts, but I'm not positive on that. The brackets also come with the screws to mount the coils to the brackets.

Hope this helped. If you still have questions don't hesitate to ask!

Connor

Here is the link also:

https://www.eficonnection.com/home/p...n-coil-bracket

drcook

thank you ! I will take further questions about them (valve covers) into another thread and any pertinent answers that would help other folks I will blend back here. Just don't want to hijack your thread.

twichy2011

I think torchtarga did the conversion on a vette with composite valve covers. He wrote a post about his install. Good luck with your conversion!

TorchTarga94

Very nice, great job! I wish I could use the EFI Connection bracketry on my composite covers. They were of little help when I tried to email them. Mine do the job though!

drcook

I have been studying the connection and the composite bolts. There are some used ones out on eBay (valve cover bolts) and I am going to buy one. I have an idea about how to build a new bolt assembly that will work for holding down the covers and also allow using EFI bracketry. It will require some lathe work though. I need to measure the bolt flange and the threaded length. I realize that I could just go pull one but I would rather just have one to work with.

PLRX

TorchTarga94

Let me know what you come up with. There will be alternator bracket issues as well.

drcook

TorchTarga94, read you PMs and/or email and respond back to what I sent you

TorchTarga94

twich- Did you have any problems with the coil bracket clearing the alternator bracket?

twichy2011

I didn't have any issues with the bracket. I did have some clearance issues with the coils and and the asr cover and the AIR tubing on the drivers side which is why the coils are flipped.

Connor

drcook

As soon as I get over the recent shoulder surgery I had, I am going to start working on my idea to be able to use their brackets on later composite valve covers. I have an idea, I just have to machine the parts on a mill and a lathe and right now I am not allowed to pick up anything heavier than a cup of coffee or even drive because the surgeon is concerned if someone pulls out in front of me I could rip out the repairs doing evasive maneuvers.

I thought about just getting a set of the 1st year LT1 valve covers, but they are hard to find at a reasonable cost.

twichy2011

Well 818 miles on the conversion and the cheap WPS opti so far and its still running strong.

Good Luck with shoulder recovery drcook. I've had two surgeries and the recoveries aren't fun.