In 1998 I bought a Triumph Herald 13/60, here you can read about it's restoration and share in a few photo's from it's travels. Please feel free to leave comments to any of the posts, of even email me if you want to.

Monday, August 13, 2012

Megajolt (Part 1)

As part of my engine rebuild I will eventually add Megajolt, a completely electronic ignition set-up. Whilst the Aldon Ignitor electronic ignition system I've had running for around 12 years has proved extremely reliable (except for one hiccup) it can only do so much to take up wear in the distributor and the gear that drives it.

Megajolt uses the Coil Pack, Crank Sensor & EDIS unit that can be found on many 90's Ford's, linked into a fully programmable ECU. The benefits being that timing is set by a 36-1 trigger wheel on the crank pulley and the timing map can be changed to however you want it.

The Ford items are widely available on Ebay, at your local breakers or directly from the UK supplier Trigger-Wheels.com. Prices on Ebay seem inflated, so if you don't have a local breakers that can help, the parts needed can be ordered direct from Trigger-Wheels.com.

The one thing that made sense to do before the engine goes back together is fit the trigger wheel to the crank pulley, everything else can be done easily with the engine in situ'. I'll be putting the rebuilt engine in with the existing set-up initially, then once I'm happy all is well I'll change the ignition over. 

The trigger wheels are available in a variety of sizes to suit your pulley, I chose to go for one with an outer diameter of 5.125" with a 4" hole. This is slightly larger than the actual pulley, so ideal.

Getting the trigger wheel central on the pulley is a must as the sensor has to be less that 1mm away from the teeth, anything other than perfect and you have wasted your time, effort and money. I entrusted this to a local retired engineer who machined a recess on the back of the pulley, then made a thin spacer to fit over the recess. The spacer then had it's own recess to accept the trigger wheel.

The spacer was clamped to the pulley then welded on. Some say you can't weld steel and cast iron, but as long as you do it nice and hot it should be fine. Then the trigger wheel was placed on the recessed spacer with the missing tooth right on the TDC mark on the pulley.

The missing tooth tells the sensor where TDC is and the sensor needs to be mounted 90° before it. Conveniently the sensor can be mounted 90° before on the Herald engine, but if it's not possible to mount here the trigger wheel and sensor should be rotated to a suitable spot.

You can read in more detail here.

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