Here we will show you how to time up and gap a Cosworth Phase sensor for those on Weber Management.
This is a simple job, but you need to know how.
Firstly the engine must be precisley timed to TDC, (See other articles for how!)
Once the engine is at TDC, the distributor cap needs to be removed.
Inside you will see a rotor arm and ark sheild, these can both be removed.
You will now see the phase sensor.
At TDC the rotor arm, or rotor arm lug should point towards the scribe mark in the Distributor body. This must be accurate (within 4 degrees) You can make up a pointer using an old rotor arm if needs be, but its quite easy to get a striaght viewpoint at the sensor and judge when it is aligned.
Here you can see the Scribe, and how the cut out on the center shaft is direclty pointing at this scribe line.
To adjust, slacken the Disributor retaining bolt and rotate the Disributor body untill the Phase alignment is correct.
Dont panic about changing the ignition timing. this is controlled by the ECU, not the Distributor!
Firstly you must ensure the center shaft of the Distributor has no excessive play. If the bush has worn and the shaft moves from side to side you are waisting your time trying to gap the Phase sensor.
We can help with a replacement oil lite bush for the distributor.
To Gap the sensor, you must turn the engine over untill the cam on the center shaft is directly in line with the sensor pick up point.
Here you can see the Sensor is in alignment with the cam.
The gap needs to be 0.3mm.
The securing screws on the Sensor can be slackened and the sensor moved to get the gap correct at 0.3mm.
It is vital here to ensure the Sensor gap is even thoughout the whole length, as you can see above, its possible to get a correct gap and correct feel on a set of feeler gauges, but the gap may only be correct at one point. Some long nose pliers can be used to manipulate the sensor bracket to create a level gap.
Any signs the sensor has touched the cam during use, it is advised the sensor is replaced.
We often see phase sensors plugged in backwards causing non starting cars. This shows how the plug SHOULD be plugged in.
Rebuilding the Distributor
We have a Distributor rebuild kit available on our webshop, removing the excessive play in the center shaft which changes the phase gap.