Introduction to 240Z, 260Z and 280Z ignition upgrades
Assuming an engine is mechanically functioning correctly, there are two ‘ingredients’ that directly make up the performance of the engine. These are fuel and spark. In this guide I cover various ignition upgrades right from the bare bones ‘if you do nothing else’ modification up to full ECU controlled ignition.
A good ignition upgrade for your Datsun 240Z, 260Z or 280Z can not only improve power but fuel efficiency as well. Better spark means better burn. Precise better spark means best burn. See where I going?
If you are using a factory points and ballast resistor ignition system – read stage 1 and get rid of those nasty points! Wanna know why? Well read on!
Stage 1 – Pointless ignition (its a real thing!)
Ok, so why remove the factory points and ballast resistor? The reason is in how points ignition operates. The mechanical points rely on the cam within the distributor to open and close. Normally the points can be adjusted in and out to determine open and close time.
As the points are driven by the cam, points are open and closed for a fixed angle of engine rotation – dwell angle. A fixed angle of operation means that as RPM climbs the time for operation decreases. How is this a bad thing? Well ignition coils require time to generate the primary magnetic field that is collapsed onto the secondary windings to create the ignition voltage. Too short of a time and the secondary voltage is low, too long of a time and you risk damage to the coil from the heat generated by the current passing through.
This is where the ballast resistor comes in. It’s purpose is to limit voltage so that at idle the coil is not damage due to longer the optimum dwell times. So a points system really provides the inverse of what an engine needs. too much dwell time at idle, tending to shorter dwell times as the RPM climbs limiting the effectiveness of the coil where you need a stronger spark all limited by a reduced voltage through a ballast resistor! Points also wear out and require replacement from time to time.
So what options are there to replace the faithful ol’ points?
280ZX Non Turbo Distributor
Thanks fully towards the later early Z car models Nissan provided an electronic ignition by default. The 280ZX was offered in EFI and as such points were done away with.
This option may be the most cost effective but relies on second hand part supplies and that will vary where ever you are in the world. The 280ZX distributor you want is the E12-80 ‘matchbox’ style model not the turbo style distributor. The primary benefit of this unit as full voltage can be applied to the coil giving much better spark.
When I purchased my 240Z it already had a 280ZX distributor installed, not very well however. Some wiring changes are required to eliminate the ballast resistor and, if you’re in the 240Z camp, some alteration for this setup to work with your tachometer. Be sure to pair this with a good quality coil designed for non-ballast systems.
If buying a second hand module be sure to check if the magnetic circle below the reluctor is not damaged. If this is cracked the magnetic field is greatly reduced and the microcontroller’s ability to identify ignition events is diminished – this happened to my distributor and I upgraded to the option below.
The below are two recommended resources to assist with rebuilding and installation of a 280ZX distributor into older model Z cars:
Electronic points replacement
The other option to simply replace the mechanical points with an electronic version. A number of manufacturers exist in this space.
I personally recommend a Pertronix Ignitor module (refer left image for install in my L24 distributor). I have only good things to say. They’re well priced, feel like quality, work well and can be used as a trigger for more advanced systems – see stage 3. No modification is required to integrate with the standard 240Z current sensing tachometer as well.
Hot Spark (E-spark in the EU) make a similar unit to the Pertronix, however I have not tested this.
Replacing the points and ballast resist with electronic points allows full voltage to the ignition coil. A good coil is also required for the other stages as well. Be sure to update the coil at the same time. Electronic points manufacturers may make or recommend a paired coil for best performance. I have used various coils and always land back with the faithful and reliable Bosch GT40 coil which I have used with all my ignition upgrades.
Replacement distributor alternative
123Ignition make a programmable replacement distributor for the L series which is also a viable option. It does require some technical progaming ability and a smart phone with bluetooth to program via the 123Tune+ app. The app also can be used as a security lock. This may may not be for everybody.
Removing vacuum advance (triple carbs)
If you are using multiple carburettors (eg. triple Webers, Dellortos, Mikunis) chances are your available manifold vacuum is less than the factory setup. This means the vacuum advance component of the distributor it is unlikely to be effective and this will affect the total amount of ‘at in’ ignition advance.
On a previous iteration of my l28 stroker motor I used triple 45DCOE152 Weber carbs. My solution was disconnect and lock out the vacuum advance. I wanted my initial ignition timing close to factory but my all in advance teh same as vacuum + mechanical advance. So I swapped out the mechanical advance bar at the bottom of the distributor rotor button tower with one that increased the mechanical advance. The bars have a number stamped into the surface. The amount of advance provided is double that number (I used a 12 in my weber build). This can also be done by lengthening the slotted holes but will need verification essentially by trial and error.
Stage 2 – Capacitive Discharge Ignition (CDI)
Stage 2 builds on the Stage 1 ignition upgrade and gives you a better, reliable trigger and full voltage to the coil. Addition of CDI box gives a quick charging strong spark.
What is this CDI sorcery?
How CDI systems work is thanks to capacitors. Capacitors are a form of batteries that can physically store energy. This is useful to ignition systems as the energy can be discharged instantaneously unlike traditional ignition coils which require time to generate and collapse a magnetic field to generate the high voltage needed for an ignition spark.
The short stronger spark produced by CDI systems greatly benefits the upper rpm range. This is not very good for low load and rpm conditions which require longer spark durations to complete combustion. Most manufacturers use multiple sparks over a short period of crankshaft rotate to combat this.
A con to the CDI unit is the amount of electrical noise created by the process. This is why manufacturers phases CDI out from OEM in the late 80s for coil over plug with the rise of more sensitive electronics in cars.
I recommend MSD as a brand. I have had the same 6AL unit as my 240Z ignition upgrade for over a decade and it has been used on all three stages of ignition upgrade in this guide. MSD are synonymous as a brand in the CDI area and are constantly updating their product lines. The 6AL has been revised into a small housing than the decade old unit I use and is also offered in a fully digital 6AL2 unit. Other brands exist but I have not tested these. Alway refer to the manufacturer’s installation manual, you are dealing with high pre-voltage for your ignition coil and don’t want to stuff it up!
Most CDI units cannot be used with the factory tachometer. Most tachometers use the ignition coil primary voltage supply as a trigger and a CDI supplies the primary voltage in the tens of thousands of volts. This will quickly destroy your tachometer. It’s not the end of the world, it just means you may need a convertor box if you’re running an older tachometer.
If you want to know a little more about early Z car tachometers, check out my YouTube video.
Stage 3 – the ‘all in’ ignition upgrade option
This is the ducks nuts end of the 240Z, 260Z and 280Z ignition upgrade spectrum. We’re talking an ECU controlled fully programmed ignition. A number of configurations exist attracting various price tags. You can maintain a distributor based ignition or migrate to a coil over plug application. Each have different requirements and I recommend conducting your own reserach or speak to a professional but in general you need the following:
- engine speed inputs (ie, RPM, crank position reference)
- engine load input (eg. MAP, TPS)
- an ECU
- ignition module (eg. coil or coils, CDI unit)
Distributor vs COP
At the time of writing I personally run a distributor based ignition for my twin hitachi L28 stroker motor using an L20ET optical trigger distributor, Megasuirt MS1 ECU running MAP input and an MSD 6AL CDI unit. This is my personal preference as I can maintain a factory aesthetic, I already had the MSD 6AL unit and the overall setup is simple.
If you plant to run a CDI it is likely to be negligible performance difference to coil over plug. Coil over plug has an advance over a single plain coil however because the time between ignition events much less for a single coil servicing an whole engine in comparison to coils servicing individual cylinders. Other things to consider if deciding between distributor and COP:
- COP requires a crankshaft position reference for the ECU to understand the orientation of cylinder 1; distributor only needs RPM and the distributor itself sends the ignition to the correct cylinder
- limitations on ECU to control multiple coils
- a COP installation is 100% custom
- additional cost for coils and wiring
Distributor based ignition
If maintaining a distributor based ignition you only require an engine RPM trigger. This can be done by:
- locking the mechanical and vacuum advance in the distributor and using a 280ZX or electronic points module from stage 1
- Factory Nissan L28ET or L20ET optical trigger (I had to change the oil drive drive to fit the L20ET to my motor)
- Fit an alternative trigger distributor
- A replacement distributor with the necessary trigger
- EFI Hardware are the only manufacturer I know of: https://www.efihardware.com/products/1752/distributor-full-sequential-for-Nissan-L-series-6-cyl
COP (RPM + engine reference) based ignition
Most COP setups are custom made using triggers on the crank. Typically a missing tooth sensor is commonly used as one sensor can be used to determine engine RPM and TDC of cylinder 1. Setups can be variable and I recommend you complete your own research.
One Six Industries make a distributor replacement which features the necessary triggers. However the format of the signal may not be appropriate for your ECU.
Now there are a swag of options here and I’ve only covered a couple. There are DIY kits using open source coding (Speeduino) all the way through to purpose manufactured ECUs specifically designed to control ignition only in difficult environments (Haltech VMSD). Again conduct your own research to match your own goals and requirements and if you are organising a professional to install and tune, talk to them first. My build uses a Megasquirt MS1 on a V3 board which I assembled and tune myself.
Well I hope you got value from this guide. As a minimum get rid of those nasty outdated points as a minimum ignition upgrade for your 240Z, 260Z or 280Z! That recalcitrant technology has no place in the modern world so be sure to consider stage 1.
I’ve covered the various 240Z ignition upgrade iterations that I have used personally, except COP. Be sure to check out my other socials for Built On Purpose and feel free to reach out and I will help where I can!
My L28 stroker build: https://builtonpurpose.co/diy-guides/l28-stroker/