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I am doing an Engine swap in my Isuzu Gemini, putting in an injected G180W twin cam 1800cc (Image attached).
I will be installing a Haltech 550 Elite ecu and currently looking at trigger sensors.
I have found a trigger kit (Image also attached) for this engine and have been advised for the ECU to control timing I will need to lock the shaft in the distributor (Will be running the standard coil and dizzy setup still).
Can anyone explain how this works as I am struggling to wrap my head around it.
The way I see it the timing is set mechanically and I don't understand how the ECU can control the dizzy from that point.
Am I best to upgrade to an electronic ignition kit and do away with the dizzy full stop or will this work?
I'm not familiar with that engine and it's going to depend on the distributor setup. From the photo I can see there is a vacuum advance mechanism and this means there's also likely to be centrifugal weights in the dissy to provide an advance curve relative to engine rpm. Basically the ignition timing isn't controlled by the ECU but instead is a function of the weights in the distributor. To fit modern EFI you'll need to lock up the distributor so that the vac/weight advance system can't change the timing. You'll also want to convert to electronic ignition instead of points and this way the ECU can control advance. The reason this can work is that the rotor arm is quite long and hence it is in contact with the individual posts for quite a long period of crank rotation so provided the dissy is aligned so that the rotor arm is beside the post across the range of timing you need to use, that's what you'll get.
You do need to be mindful of the base position of the dissy in this sort of setup though or you can end up with cross firing in the dissy cap. I align the rotor arm so that it's just about to leave the post at the minimum timing you want to run (say 0 deg for example). Then when the timing is advanced you can be sure your alignment will be correct.
I believe it has electronic ignition already but I will double check and convert if not, the original SOHC version of the engine had points but was easily converted over.
Your explanation is perfect, I understand how it works now. My previous understanding was definitely not correct.
Thanks again for your help.