Setup of electronic Ignition (FAST/Crane XR700/XR3000)

Mental Preparation

This job is about my least favourite on the car, and very critical to engine running. It's a bit like kissing your mother-in-law hello/goodbye because you love your wife. 

The job is difficult because it is physically uncomfortable; alignment by sight is extremely subjective; the procedure is simple on paper but difficult and a little indeterminate; and the parts are fiddly with tiny fasteners that want to make their own way to the most inaccessible spots. 

I wish I wish that Pertonix made a kit suitable for the V12 EFI; their kit is much better designed with a replacement metal base plate which removes the last 3 of the discomforts I mentioned above. If you have a carb V12, try their kit first and you wont need these tips. Don't try it out like I did for a normal XJS because the trigger board needed for an EFI car will not fit. 

Tips up front

To overcome the difficulties outlined above (if you aren't familiar with one or more then you are lucky) here are some key learnings up front:

  1. Comfort
    1. Jack up only one side of the car (and support with stand) to rotate the engine to the 10 deg BTDC static timing position. You will then be able to lean over the engine from the other side to reach into and observe the area around the distributor. 
    2. Allow time to perform this procedure without needing to rush.
  2. Sight alignment
    1. Mark the position of the No1 electrode onto the distributor base as suggested by Bernard Emden in his writeup. This helps align the rotor with the cap off, and help is needed.
  3. Procedure
    1. Buy a new XR700/XR3000 that has the diagnostic LED, or you will have to jury rig your own 12V test light. (See LED shown with the inspection camera below).
    2. The most practical place to install the ignition box is on the radiator cover near where there are holes in the vertical fold to pass the wires through. The power wires route above the radiator and the sensor wires straight to the dizzy (there is a connector included in the wiring in case it needs to be temporarily retracted). 


    3. I made a little tab thing (a bracket for the sensor bracket) to stop the wires from drifting up into the rotating trigger disc and getting messy.


  4. Fiddly parts

    1. Mount the sensor very loosely onto the base plate before fitting, to prevent the little washers and screws from falling into inconvenient locations. 
    2. I use a Milwaukee M12 Digital Inspection Camera to find the washers and things that do fall down and don't want to be found. This has an included light and rotating head. I like it partly because I have a minor fetish with the M12 gadgets but it is actually effective for those tasks with old eyes and normal hands. (Also shown in background is the red diagnostic LED on the unit I used for set up). A magnetic head would be even better, to pick up those small parts.


Procedure

Start with the right parts: for the XR700 (totally adequate)

    • Part number is 700-0300 including the V12 distributor kit.
    • Use coil PS20 Part number 730-0020.
    • You will need to use the supplied diode and your ballast resistor to wire in.
    • The sensor bracket to use is the one included with the V12 trigger disc.

You can download the manufacturer procedure from Summit or Triumph/Spitfire (FAST get your act together). 
The most important parts of the procedure are the wiring diagram (Figure 21 posted below) and the "Optical Trigger Adjustment Procedure" on Page 8.

Connect the system using Figure 21 from the manual. (For XR3000 I think you use a PS4 coil and bypass the ballast resistor.) My ECU does not have the white/black connection and seems happy.

 

Alignment

This is the no-fun part. Even in this write-up I procrastinated before doing this part.

The base plate re-used for the optical sensor is designed to rotate with vacuum advance. So, sensor position relative to rotor position is made by adjusting the whole upper distributor housing. However this also adjusts the relative position of the cap electrodes to the rotor.


The simple version of the alignment procedure is shown in black; tips added in blue.
  1. Rotate engine at crankshaft to 10 degrees BTDC on the timing mark, so that the rotor points to distributor electrode for piston marked 1 (in firing order).
  2. Loosen adjuster at front of dizzy (13mm) and position screw to most anti-clockwise adjustment.
  3. Remove slack from rotor by moving it clockwise by hand (springs should push it there). 
  4. Adjust dizzy base so that the gap in the trigger disc (that rotates anti-clockwise with engine operation) is a few mm anti-clockwise of the sensor LED. Tighten the lower housing down. 
  5. Rotate the upper distributor slowly clockwise (opposite to engine rotation) with the adjustment screw, until the sensor activates the diagnostic LED.
  6. Check that the rotor position relative to the electrode will allow another 30 or so degrees of advance (from 10 to 38), requiring the cap electrode to be close to the trailing (left) edge of the rotor electrode. This why marking the position of the cap electrode onto the bottom housing is important. 
  7. Lock down the distributor. LED should remain on with rotor in most clockwise position of slack.
  8. Re-install the trigger board without dropping any parts; install distributor cap and all leads.
  9. Start car and check timing with engine light. 
The procedure is difficult because trial and error involves un- and re-installing the sensor and disc with the flimsy escapist fasteners to adjust the bottom distributor housing. Adjusting the sensor position with the upper housing also moves the rotor position relative to the electrode. I almost wish I had a SBC about now with 1/10th the number of parts and none of this hassle - but perseverance is an important life skill. 

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