Bailey Engineering LTCC LS1 Coil Pack Install
Anyone who has owned an LT1 powered GM vehicle has heard the dreaded word “opti-spark”. The opti-spark is basically a distributor which combines a low voltage high and low resolution portion to determine cam position location and a high voltage side which is basically a cap and rotor into a single compact package. When working correctly the opti-spark is a very accurate system to control ignition timing and keeps the engine bay cleaner by moving the spark plug wires to the bottom of the engine.
LTCC Coil Pack Conversion
Anyone who has owned an LT1 powered GM vehicle has heard the dreaded word “opti-spark”. The opti-spark is basically a distributor which combines a low voltage high and low resolution portion to determine cam position location and a high voltage side which is basically a cap and rotor into a single compact package. When working
correctly the opti-spark is a very accurate system to control ignition timing and keeps the engine bay cleaner by moving the spark plug wires to the bottom of the engine.
So why would anyone want to change such an outstanding ignition system? Although the opti-spark is a good system it just wasn’t implemented into production in a good way. Some of the materials such as the bearings and seals wear out prematurely. Also, the opti-spark is very sensitive to water. So GM’s location of the opti-spark below the water pump and cooling system air bleeder valves is questionable. Another problem is the high voltage side of the opti-spark can sometimes short out the low voltage side. This is a common problem with power-adder cars especially with aftermarket ignition boxes.
Currently there are few options to improve the LT1 ignition system. One solution is the LTCC (LT1 to LS1 coil conversion) package offered by Bailey Engineering. The LTCC system uses the low voltage side of the opti-spark, factory computer and the supplied “black box” to control eight individual coil packs. This system eliminates high voltage from going through the opti-spark. It also allows the user to control engine timing through traditional LT1 editing software programs. The LTCC box also has adjustable rev limiters and can retard timing on a fixed rate or on a per-1000 rpm basis for nitrous or blower applications. Wiring the LTCC harness is fairly simple. The only challenging part is locating the coil
packs. Expect to pay around $700 for the LTCC conversion.
QTY -- PART ------------------------------------------------ SOURCE
8 GM-12558948 COILS GM
1 GM-12562864 COIL MTG BRKT GM
1 MSD-32139 PLUG WIRES SUMMIT
1 LTCC MODULE/HARNESS BAILEY ENGINEERING
1 ½” STEEL TUBING
- MISC BOLTS/STUDS/NUTS HARDWARE STORE
Mounting the coils is where the creativity comes in. If you are frequently taking off the valve covers mounting the coils on the top of the
valve cover probably isn’t the best location. However, I don’t take the valve covers off that much so I mounted the coil packs on top. On the driver’s side valve cover I welded four ½”-20 x 1” studs to the stock valve cover. I used these studs to mount the GM coil mounting bracket to the valve cover. Each of the coil packs can then be mounted to the GM mounting bracket. The passenger’s side valve cover has the oil fill and fresh air inlet for the PVC system in the way for the GM mounting bracket to work. ½” x ½” steel tubing was used as mounting rails for the passenger’s side valve cover. More of the ½”-20 x 1” studs where welded on the tubing for mounting the coils. The studs were
positioned so the coils would not interfere with the oil fill and breather hole. The coils were then attached to the studs.
Wiring is plug and play. First choose a location for the LTCC box. Then just plug each coil pack into the wiring harness for the appropriate cylinder. Each coil pack has a ground. There are several
threaded holes in the block below each valve cover that make good ground locations. A few wires have to be tied into the existing ignition system:
1) Attach white wire from LTCC harness into white harness that fed the old coil
2) Attach pink wire from LTCC harness into both of the pink/black wires that fed the old coil
3) Connect the LTCC harness into the opti harness connector on the passenger side of the engine.
4) Replace Ignition fuse under the hood to a 20 amp.
5) Discard existing ignition coil and Ignition Module. They are no longer needed.
It's important to realize that the LTCC is not a replacement for a faulty opti-spark. If the optical section of the opti-spark is bad, i.e. you are getting codes for low or high resolution pulse failures, you will need a new opti to provide the proper signals to the LTCC box. A bad cap/rotor section won't necessarily hamper the LTCC performance since the new system does not utilize that section of the opti, but if re-using an old opti it is probably best to disassemble, inspect and clean the internals first. A set of cut-to-fit spark plug wires will be required or a set for LS1 truck engines may work depending on the coil location.