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Old 10-12-2012, 08:38 AM   #1
Devs93's Avatar
Join Date: Oct 2012
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Default How to get Coil per Cylinder and LSx ignition control on a L31 SBC Write up

Updated version of this writeup available at:

Well, itís another slow day here at work, so what say we do another write up? What Iíll discuss today is something that not many people have done, or even heard about at this point, but has a lot of benefits and isnít overly hard to do (though it is involved). Iím talking about how I converted my SBC vortec L31 to using 8 separate LS2 coils in a coil per cylinder setup using EFIConnectionís 24x setup. This will be another LONG write up, but hopefully will go into the required detail to perform this mod.

In my opinion, this is a great ignition system upgrade. It eliminates some major problematic things (like completely removing the cap and rotor which caused a lot of problems for me, as well as severely reducing dist gear wear associated problems.) in the L31 setup, and offers exceptional control and reliability that blows any aftermarket ignition setup out of the water IMO. It also will allow you to run a double timing chain if you want to (which is not an option on the L31 with the 4x crank reluctor) This can work on any SBC including the LTxís which are great because it eliminates the optispark crap. However each engine setup will change the requirements and installation slightly, so Iím only going to focus on my install, which is in a Gen 1e L31 5.7L vortec 350. Any different setup, youíll want to contact www.eficonnection.com for details.

Before we start, I should say, I do not work for, nor am I compensated in any way by eficonnection. Iím simply a satisfied customer who would like to share my success with their product. Any questions or comments for eficonnection should be directed to them, and not me. I will be happy to help people but with the understanding that I can only answer questions relative to my experience with the 24x setup.

Secondly, I will make the assumption that you already know about safety when working on vehicles and electrical systems, as well general mechanic knowledge (i.e. how to remove bolts and parts correctly. Without causing damage or injury). I am in no way liable for anything which may happen to you, your parts/vehicles or otherwise. This is provided for informational purposes only. Please use common sense when doing anything at any point in your life.

Okay, now with that said letís get into it. First off you may ask yourself, ĎWhy switch to an LSx style ignition setup in a SBC? Why not just swap to an LSx engine?í And you have brought up a great and valid point. An LSx swap may be preferable for many people. There is plenty of information on how to do so, and it shouldnít be that hard. LSx swaps are popular and do very well in GMT400ís. however there are some benefits to keeping the SBC too. For example Gen III engines (LS1, LQ4, LQ9, etc) produce good power, however it is much higher in the RPM range than a SBC, and I personally prefer a lower RPM power band which will provide more usable power in a daily driver situation. Secondly, LSx swaps, can get expensive, fastÖnow this is by no means a cheap upgrade, it absolutely is pricey, but with LSx swaps, you might have to look into things like serious transmission changes or full trans swaps, which may require driveline alterations, etc, that can add up quickly, this is like my setup, I run a T56 from a 1994 LT1 Fbody, if I did a LSx swap it would require some pretty severe trans modifications to work correctly, I wasnít willing to do that. Also LSx swaps can require a lot of room to complete. When I did this swap, I had a small garage that wasnít even big enough to fit my whole truck in and close the door, there was no way I could get the space needed for a cherry picker in there to pull/install the engine. No need to pull the engine or anything that intensive for this mod. Plus if youíve already done some nice mods to your existing engine, why discard them all and start over with a different non-compatible engine? Thereís nothing wrong with working on what you have, after all, that is where true hot-rodding came from.

Okay, now that is said, I do like LSx swaps, and if that looks better for you, then go for it. But for my situation, this was a better use of my time and money for my personal preferences. I DO NOT want opinions here about gen III being better than Gen I, or vice versa, if you want to start a pissing war, go elsewhere, I WILL request that any posts which stray in that direction to be removed. Sorry, but BS like that is one reason FSC is such a dump now, and I donít want that happening here.

Required supporting mods:
Okay, to do this you have to have a few things. First off, this requires a 12200411 PCM. No getting around it, period. I had this done about a year prior to installing the 24x setup. Installing the 411 combined with EFILive is by far the best mod I have ever done. Tuning your own vehicle is very satisfying and will teach you more about your vehicle than you could ever imagine. To research a 411 PCM swap, please read here: http://www.pacificp.com/forum/viewtopic.php?t=3240 I know its long, and there are a lot of tangents that pop up, but read it, it will answer most/all of your questions about the 411 swap.
Iím not going to go over how to swap the 411, that is well covered in the mega-super-thread. But understand that it IS a requirement for this mod. Plus you will need some way to tune your new setup. This could be done in a number of ways, including going through a dyno tune, mail order tune, whatever. However IME the best and ideal way to get what you want and nail everything down correctly, especially with a very custom and not widely run setup like this, you need to do the tuning yourself. I use EFILive and love it and highly recommend it, there are also other tuning suites out there which will work too, like HP tuners, and Tunercats II, all great software, I have limited experience with software other than EFILive, so do your own research to find out what is best for you.
Now, what you need to get are the following:
8 LSx coils, (I used LS2 coils)
24x reluctor wheel from eficonnection
24x crankshaft sensor (and wiring)
Distributor cover for your L31 vortec distributor
New plug wires
A way to mount the new coils
Wiring harness to connect the new coils to the PCM/power/etc
New timing cover (technically the original L31 timing cover is a one use only item and should be replaced, you can attempt to re-seal it, but realize you may end up with leaks) if you get a new cover, make sure you get one WITH the sensor hole in it, I ordered one from summit and it arrived, was identical to the stock one, except it didnít have provisions for the crank sensor.
And possibly LS1 A/C sensor/wiring
Hereís a pic of the 24x reluctor, sealed dist cap, and one LS2 coil from my setup:

Here is EFIconnectionís site for the 24x setup:
They offer many of these needed parts, including the reluctor, LS2 coils, complete wiring harnesses, or do-it yourself wiring parts for all aspects of this mod, aluminum timing covers, crank sensor, distributor sealed cap, even PCMís and connectors/wiring for that if you need it.
Hereís what I did, I got the 24x reluctor, crank sensor, sealed dist cap, coils, and all DIY wiring for the project from EFIconnection. As well as mounting setup for one half of it but Iíll discuss that later.

So in order to install the 24x reluctor, you have to strip down the front of the engine, take off things like the water pump, crank pulley and harmonic balancer, etc, basically everything in order to get to the timing cover and properly remove it. Some people need to also remove the oil pan to get the timing cover off too, so be aware of that. Once you get down to the cover, remove it. In there youíll see the 4x crank reluctor, which looks like this:

Youíll need to pull it off the crankshaft, you might need a 3 prong gear puller for this if the sucker is tight on there. Mine wasnít too bad, I just gently used a pry bar to walk it off. Just be careful not to damage anything like the timing set/etc. after it is off, push on the 24x sensor in its place. Like this:

Once itís on begin re-assembling everything, install the new 24x crank sensor into the timing cover, and itís probably a good idea to wire for the new sensor now too, when I did it EFIconnection had a nifty little adapter that you just plug the old crank sensor connector into and it had about 2-3Ē of wiring attached to the new sensor connector which correctly rewired it. I donít see it on their site right now, but Iím pretty sure they could get you one if you contact them about it. If you want to just repin the connector, The pinouts for the 24x sensor are: A-purple wire for CKP sensor signal, B-yellow wire CKP low reference, C-Pink wires CKP 12v reference

Okay, now that you have the new reluctor in, new 24x crank sensor in, and wired, and most thing re-assembled, letís work on the coil setup, first off is to pull off the old cap and rotor (good riddance), old coil and ignition module, plug wires, and such. If youíre not installing a different distributor body or anything, I would NOT recommend removing the distributor, just use the sealed dist. cap and install it on the dizzy. Here is the cap from EFIconnection, its very well made, GM does have a cap that was used on early transitional 7.4ís but its aluminum and VERY hard to find. Iíd just get the one from EFIconnection if I were you. Hereís a pic of mine:

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