How to fit a 123 distributor and use the 123\Tune+ app

A 123ignition distributor replaces your points distributor with an electronic unit that fits in the original location. There are no points to set or wear out, and once you've set the static timing with the built-in LED there's nothing more to adjust. Starting and running improve too.

This guide covers fitting the distributor and then using the 123\Tune+ phone app to connect, check live engine data and edit the advance curve. The fitting steps are the same for the switchable and Bluetooth versions. The app sections only apply to the Bluetooth 123\Tune+.

Our 123 distributors suit all 750/101 and 105 series cars, plus early points-ignition 116s. The 123s we sell are for negative earth cars only, so a positive earth 750 Giulietta needs converting first.

Don't guess the static timing point. If you can't find TDC and the timing mark with confidence, get someone experienced to do that step.

Parts you need from Classic Alfa

The simplest route on a carburettor 105 is the complete kit: distributor, coil, HT leads and plugs in one order.

Short coil lead is for cars with the coil next to the distributor. Long is for cars with the coil on the bulkhead.

Buying the distributor on its own:

Worth replacing while you're in there

Tools and consumables

• Timing light (recommended)
• 8 mm Allen key (switchable version)
• Spanner or socket for the distributor clamp
• Small flat screwdriver (for the curve switch on the switchable version)
• Ring or spade cable lugs and a proper crimping tool
• Paint pen or marker for marking the cap, pulley and block
• Something to turn the engine by hand
• A phone or tablet with Bluetooth and the free 123\Tune+ app (Bluetooth version only)

Fitting the distributor

1. Mark cylinder 1 on the old cap. Follow the HT lead from number 1 cylinder back to the cap and mark that tower. Everything else is set from this point.
2. Set the engine to the static timing point. Turn the engine by hand until the rotor points at your cylinder 1 mark and the crank is at the static timing figure (degrees before TDC). Check your workshop manual for the figure for your engine. Put a mark on the pulley and a matching mark on the block. You'll use these with the timing light at the end.
3. Choose the curve (switchable version only). Open the side cap on the body with an 8 mm Allen key to reach the 16-position switch. Turn it with a small screwdriver to position 1 or A. Both suit the Alfas we sell this distributor for, so try each and keep the one the car runs better on. Close the cap tightly.
4. Remove the old distributor. Note where the rotor points before you lift it out. The drive dog is off-centre, so it only engages one way.
5. Fit the 123. Turn the 123's rotor to point the same way as the old one did, then drop it in. It doesn't need to be in the exact position yet. Nip the clamp up lightly so it can still turn.
6. Wire the red and blue leads. Crimp a lug onto the red wire, gripping both the copper core and the insulation. Connect it to the coil positive, the feed that comes from the ignition switch. Connect the blue wire to a good earth. Leave the black wire off for now.
7. Set static timing with the LED. Switch the ignition on. Turn the distributor body until the LED goes off. Then turn it slowly against the direction the rotor turns until the LED just comes on. As you turn, push the rotor the same way to take up any slack in the drive. That's your static timing point. Tighten the clamp and don't move it again. Switch the ignition off.The green LED shows through a hole in the disc under the rotor.
8. Connect the black lead. Crimp a lug onto the black wire and connect it to the coil negative.
9. Fit the vacuum hose (vacuum versions only).
10. Fit the new cap and HT leads. The 123 cap only fits one way. Put the cylinder 1 lead on the tower above the rotor, then follow round in the same direction and order as the old cap. The centre lead goes to the coil.
11. Check with a timing light. Clip a timing light on to cylinder 1, start the engine and check the maximum advance against the figure in your workshop manual.

Using the 123\Tune+ app

The app is free on iOS and Android. It talks to the distributor over Bluetooth, so the ignition must be on for it to connect.

1. Open the app. The first time, it asks for location access. Tap Always Allow, as the GPS speed reading needs it.
2. Connect. Switch the ignition on with the engine stopped. With Bluetooth on, your 123\Tune+ appears under Settings, Devices. Tap it.
3. Enter the PIN. The default PIN is 1234. A green dot at the bottom left of the dashboard means you're connected. Red means you aren't.
4. Change the PIN. Go to Settings, Change pin, and enter the new one twice. Do this before you use the immobiliser.
5. Turn on the immobiliser if you want it. With it on, the engine fires a few times at low revs then stops sparking.
6. Set your units. In General settings you can set the speed units, temperature, pressure units, 12 or 6 volt battery and the clock. Prevent auto-lock keeps the screen awake.

The blue LED on the distributor tells you its Bluetooth state. Solid on means no phone is connected. Off means it's connected or has no power. If it flashes for several minutes, restart your phone and reconnect.

The dashboard

Back on the Dashboard tab you get live readings from the engine:

• Crankshaft advance: total timing, made up of the centrifugal curve, the vacuum curve and the static setting
• RPM
• Vacuum (manifold pressure)
• Battery voltage
• Coil current, a guide to spark energy
• Distributor temperature
• Road speed from the phone's GPS

Real-time tuning

The Tune button only works with the engine running. Each tap of plus or minus moves the timing 1 degree, up to 10 degrees either way. Nothing is saved. Note the result and put it into your curve afterwards. It's meant for rolling road work.

Editing advance curves

The 123 works in crankshaft rpm and crankshaft degrees. Most workshop manuals give curves at the distributor, so double every rpm and every degree before you enter them.

1. Read the current curve. Connect with the ignition on and the engine off. Open the Curves tab and the app reads the curve from the distributor. You can also tap Read.
2. Edit the centrifugal curve. Scroll down and tap Edit centrifugal curve. Tap any rpm or degree value to change it. Add points with Add point, up to 10, and remove them with the bin icon. The curve always runs from 500 to 8000 rpm, and your last advance figure is carried on to 8000 rpm.
3. Set the rev limiter. Change the Max RPM value. Above it, the 123 skips sparks to hold the revs down.
4. Edit the vacuum (MAP) curve. Tap Edit MAP curve. Enter values in kPa, worked out as shown below. If your car has no vacuum advance, turn the MAP curve off.
5. Tap Done, then Write. Done only changes the curve in the app. Write sends it to the distributor, and only works with the engine off and the ignition on.
6. Save a copy. Tap Save file and give the curve a name. To use it again later, tap Files, pick the curve and tap Open. You can then edit it or write it to the car.

Worked example: converting a Bosch curve

Published curves are drawn between two tolerance lines. Take the middle of the two. These are 123's own example figures.

Vacuum figures need two more steps. Multiply mmHg by 0.133 to get kPa. Then take that from 100, because the 123 uses absolute pressure and atmosphere at sea level is 100 kPa.

The 100 kPa point is fixed at 0°. Values below 100 kPa are advance. Values above it are retard, must be negative, and are only used on turbo engines.

The static advance box in the app is for display only. It adds to the dashboard total but doesn't change the timing. Static timing is set by turning the distributor body.

Tips and common mistakes

• Leave the black wire off until the static timing is set. The LED method relies on it.
• Turn the body against rotor rotation when setting the LED. If your distributor turns anticlockwise, turn the body clockwise.
• Fit a new coil to get the best out of the 123. 123 specify a primary resistance of 1.4 to 3.0 ohm for four-cylinder engines, and the 3 ohm Flame Thrower sits within that.
  
• Crimp lugs onto both the copper and the insulation. A loose crimp gives intermittent misfires that look like an ignition fault.
• The 123s we sell are for negative earth cars only.
• Writing a curve needs the ignition on and the engine off. If the 123 is wired through the ignition switch, turning the key off cuts its power.
• Only change advance curves if you understand ignition timing, ideally with access to a rolling road. Too much advance can cause detonation and engine damage.

Ready to start?

We're based in the UK and ship worldwide, including the EU, Australia and the USA. Not sure which distributor suits your car? Tell us your car's model and year and we'll tell you which parts fit.

Further reading

• How to install the 123ignition distributor (video)
• 123\Tune+ App introduction (video)
• 123\Tune+ App: editing advance curves (video)
• 123\Tune+ app manual
• 123ignition curve tutorial
• 123ignition support and FAQ