What the Dual-Sync gives you
FAST sells this distributor as part numbers 305005 and 305017 (the small block Chevy version). It's a FAST part, so it isn't something Haltech sells, but it works well with an Elite. Inside are two Hall effect sensors:
- An 8-tooth trigger that gives the ECU engine speed and position.
- A single-tooth sync that tells the ECU which part of the four-stroke cycle the engine is in.
That sync signal is what makes fully sequential injection possible, so this distributor is a common choice for older V8s that need a better trigger. Because it's a distributor, check rotor phasing too. See distributor rotor phasing.
Wiring
There are two versions of the harness, an older "classic" color code and a newer one. Identify yours before you crimp anything.
| Function | Pin | Classic color | New color | Haltech wire |
|---|---|---|---|---|
| Sensor power | - | Red | Red | Red 12V+ in the trigger 4-core |
| Crank (8-tooth) signal | F | Brown | White | Yellow Trigger+ in the trigger 4-core |
| Cam (sync) signal | C | Yellow | Black/White | Yellow Home+ in the home 4-core |
| Sensor ground | D | Black | Black | Signal ground (black/white) |
Both sensors are Hall effect, so they have a real power feed and ground, and they need no reluctor minus wires. If you're unsure about a Hall sensor's pins, our guide to determining Hall effect sensor pinouts will help.
The one-cable trick
A standard Elite harness runs two shielded 4-core cables to the triggers. For a Dual-Sync, the trigger cable has almost everything you need: 12V, signal ground and Trigger+. Its fourth wire, the green Trigger-, is left over because a Hall sensor has no negative signal. From the home cable, the only wire you need is Home+.
So instead of running both cables, you can re-pin the unused green wire at the ECU plug so it carries the Home+ signal. Then one cable carries all four connections to the distributor.
| ECU | Step 1: remove and insulate | Step 2: move |
|---|---|---|
| Elite 550, 750, 950 | Yellow wire at pin A32 (not used) | Green wire from A33 into A32 |
| Elite 1000, 1500, 2000, 2500 | Yellow wire at pin B2 (not used) | Green wire from B5 into B2 |
At the distributor end, that green wire now goes to the cam signal pin. Insulate the pulled yellow wire properly so it can't short against anything, and label the change for the next person who works on the car.
After re-pinning, use the ECU's trigger diagnostics to confirm both signals show up before you try to start it. A swapped wire here gives you a no-start that looks like a sensor fault.
Software setup
You'll configure the trigger in the Elite's trigger setup for a Hall effect 8-tooth trigger with a 1-tooth home. If you'd like our settings screenshot for this distributor, ask us and we'll send it over with advice for your build. Always finish by confirming timing with a light. Our Hall effect distributors article has more background.
