Fitting a Crank Trigger Wheel: -

Date	Discussion
April 2023	The Crank Trigger kit, sourced from Luke Hoffman @ www.sonicinjection.com.au, duly arrived and was most professionally made and was complete with all the necessary nuts, bolts, plugs and fittings. Crank trigger wheels come in a number of different configurations and this one has 36 "teeth", with one missing to identify the Top Dead Centre (TDC) position. The Variable Reluctance (VR) sensor provided was a Ford product,, number 4621599, which is made by Delphi and used in a wide range of vehicles. The electrical output from a VR sensor is a sine wave whose amplitude varies considerably with speed. Speeduino cannot accept the signal directly but does have provision, on the PCB, to mount an optional VR "conditioner". Suitable units are available from www.eficustoms.com.au and are very simple to fit. The only other modification to the Speeduino board was to change two small jumpers. Testing the Speeduino configuration on the bench, before installing it on the engine, required a method of spinning the trigger disk and mounting the sensor. An old battery electric drill (with a variable power supply and no battery) was attached to some scrap plywood, together with the sensor, all of which worked well - to a point. The problem with this design was immediately apparent on the first test - it was too slow! Battery hand drills are only designed to run up to about 1000rpm. So, a Mark II unit was required. This was made using a radiator fan motor which easily exceeds 6000rpm and was scary enough in operation, at that speed, to make safely enclosing it in a box seem like a really good idea! The output signal, connected via a screened cable, was very clean and the Speeduino accepted it immediately. Changing one software setting to let the ECU know that the trigger signal was in a different format, and all was well. The ECU is now complete and set-up on the bench for testing. The basic settings such as engine size and type have been entered and it all seems to work as expected. The actual injectors are connected and can be heard operating, (and seen on the oscilloscope), all of which is comforting. Fitting the trigger wheel to the engine is straightforward, it has three holes that align with another set, already provided, in the standard harmonic balancer. The sensor is mounted via a bracket that is custom made to fit onto two of the existing bolts that secure the timing chain cover. The bolt holes in the harmonic balancer are normally used to attach a second fan pulley which, in the standard vehicle, is used to drive the air conditioning compressor. However, Rhapsody has made use of that second pulley to drive a larger size alternator. The standard Holden alternator, in 1965, was a 35A unit, which is very small by modern standards. So, I fitted a 130A unit. This entailed making custom mounting brackets and using the additional fan pulley to correct fan belt alignment. Now, deciding to fit a crank trigger wheel has required all that to be changed. Happily, in the years since a 35A alternator was the best that could be achieved, the DIY upgrade market has made available a much more powerful unit that fits directly onto the original mountings. So, a new, 100A version of the alternator has been purchased and all the custom fittings, together with the second fan pulley and the bigger alternator, have been discarded and the original Holden mountings re-installed. Now the crank trigger wheel can be fitted very simply, as intended.

Date

Discussion

April 2023

The Crank Trigger kit, sourced from Luke Hoffman @ www.sonicinjection.com.au, duly arrived and was most professionally made and was complete with all the necessary nuts, bolts, plugs and fittings. Crank trigger wheels come in a number of different configurations and this one has 36 "teeth", with one missing to identify the Top Dead Centre (TDC) position. The Variable Reluctance (VR) sensor provided was a Ford product,, number 4621599, which is made by Delphi and used in a wide range of vehicles.

The electrical output from a VR sensor is a sine wave whose amplitude varies considerably with speed. Speeduino cannot accept the signal directly but does have provision, on the PCB, to mount an optional VR "conditioner". Suitable units are available from www.eficustoms.com.au and are very simple to fit. The only other modification to the Speeduino board was to change two small jumpers.

Testing the Speeduino configuration on the bench, before installing it on the engine, required a method of spinning the trigger disk and mounting the sensor. An old battery electric drill (with a variable power supply and no battery) was attached to some scrap plywood, together with the sensor, all of which worked well - to a point. The problem with this design was immediately apparent on the first test - it was too slow! Battery hand drills are only designed to run up to about 1000rpm. So, a Mark II unit was required. This was made using a radiator fan motor which easily exceeds 6000rpm and was scary enough in operation, at that speed, to make safely enclosing it in a box seem like a really good idea! The output signal, connected via a screened cable, was very clean and the Speeduino accepted it immediately. Changing one software setting to let the ECU know that the trigger signal was in a different format, and all was well.

The ECU is now complete and set-up on the bench for testing. The basic settings such as engine size and type have been entered and it all seems to work as expected. The actual injectors are connected and can be heard operating, (and seen on the oscilloscope), all of which is comforting.

Fitting the trigger wheel to the engine is straightforward, it has three holes that align with another set, already provided, in the standard harmonic balancer. The sensor is mounted via a bracket that is custom made to fit onto two of the existing bolts that secure the timing chain cover.

The bolt holes in the harmonic balancer are normally used to attach a second fan pulley which, in the standard vehicle, is used to drive the air conditioning compressor. However, Rhapsody has made use of that second pulley to drive a larger size alternator. The standard Holden alternator, in 1965, was a 35A unit, which is very small by modern standards. So, I fitted a 130A unit. This entailed making custom mounting brackets and using the additional fan pulley to correct fan belt alignment. Now, deciding to fit a crank trigger wheel has required all that to be changed.

Happily, in the years since a 35A alternator was the best that could be achieved, the DIY upgrade market has made available a much more powerful unit that fits directly onto the original mountings. So, a new, 100A version of the alternator has been purchased and all the custom fittings, together with the second fan pulley and the bigger alternator, have been discarded and the original Holden mountings re-installed. Now the crank trigger wheel can be fitted very simply, as intended.