Because I can't leave things alone, I've decided on a bit of an upgrade to my engine control.
Plus the forum has been on the quiet side of late, so I will take one for the team and do some more project work
Currently, my ECU is triggered by the pickup in my MSD distributor. This trigger (like most V8 distributors) sends 8 signals per engine revolution. It's obviously driven by the timing chain from the crank to the camshaft and then by the cam gear.
While this method certainly works, there can be slight inaccuracies because of the timing chain and gearing. You can notice this on most distributor based cars with the timing wandering a little when using a timing light.
I'm going to switch to using a toothed wheel and sensor on the crank, which is what the later windsors used. This gives the benefit of 36(-1) events per crank revolution, so much more precise, but it's also connected directly to the crank, so there's no chains or gears to allow any movement.
I also currently use a MSD 6A unit to send spark to a MSD blaster coil.
This will change to using 8 LS1 coils in a wasted spark mode, which means that two of the coils will spark at the same time. For one of them, the cylinder will be on the firing stroke, and the other will be at the bottom of the exhaust stroke (so won't actually have anything to ignite).
I'm going to wasted spark mode rather than fully sequential spark because I'm running the Microsquirt (rather than Megasquirt) which is a smaller unit with limited outputs. It also means I only need a crank sensor, and not a cam sensor as well.
This fellow has used those coils on his windsor using the standard coil brackets:
Not a fan of that setup though, so I will make custom brackets welded to my rocker covers like our (filthy holden) friend krisr did on his HQ monaro. It's a much nicer setup.
The 36-1 wheel is 3mm thick, so I will remove my crank pulley and machine 3mm off the rear of it. This means all my other pulleys will still line up. It's an alloy pulley and seems to have plenty of meat on the back of it to do this.
I will remove my MSD distributor and either put an old distributor back in with everything removed from it, or get an explorer cam sensor. It's just to drive the oil pump and nothing else.
Last edited by hybrid on Tue Mar 08, 2016 11:00 am; edited 2 times in total
Thanks for the offer Luke. I actually looked at EDIS first, but then realised I could do wasted spark with Microsquirt. I'm not a fan of the EDIS coils, and I like the thought of Microsquirt looking after it all with no "middle man".
Boof, I have been tempted to go that route too believe me. However, that 8 stack setup won't fit with my real future plans (if I'm lucky enough to do it), where having accurate timing will be more important... hint hint
I can't believe that everyone that's into cars wouldn't want to get into this stuff. It's great fun.
I agree it is great fun.
I think know what your plans are as you told me what you were thinking when I was with gbx and visited. G did tell me it was the size of the lump which makes it impressive!! Not sure I understand - lol.
So are you prepared to discuss in more details as yet?
I don't want to say too much in case it never happens - you know.. one of those blokes who says stuff but really never does any of it. The wife has given me the OK a couple of times, I'm just not sure it's smart right now. Got #2 on the way.
In any case - this current change should cost me under 300 bucks and is a good upgrade whether I decide to force the other issue or not.
Got second hand genuine from ebay - about $70 inc post.
Krisr has a spare original harness he will give me that I will cut up and modify.
To add some info to the post, firing order for HO and standard 302 respectively:
You can use either cam with the same windsor crankshaft. This provides a bit of a hint as to which cylinders are 180 degrees crank angle apart from each other, and which should be paired together for wasted spark.
The wasted spark grouping will be as follows:
Some more technical info related to my model of Microsquirt in particular.
My model (V1 - actually a Beta testing unit) has two built in ignition transistors so I could drive two coils directly. Because of the physically small footprint of the Microsquirt and the relatively high noise of an ignition coil, in later versions they decided to remove these ignition drivers and switch to low level 5V ignition outputs.
Now because I need 4 ignition outputs for V8 wasted spark, I will need to reconfigure two of the LED output wires as ignition outputs. However because of the built-in ignition drivers, the output polarity of the two regular ignition outputs and the LED outputs will be different.
To counter this, I will open up the Microsquirt and remove the built-in ignition drivers and bridge their connections. This will make all 4 outputs the same.
The LS1 coils are "Logic Level" coils, which means they have a built-in igniter (to charge the coil) and only need to be triggered by a logic level (5V on/off) signal.
I had a look at the msd crank trigger and it I over $300. It uses four magnets yet the one you are using works on the Hall effect. With more slots I would think your choice is better as it give a more accurate idea of crank position/angle.
'68 J-code GT Fastback
'67 S-code GT coupe, 'Pink Bitz' formerly known as 'Hookin' up a brother'
'69 M_____ GTS Fastback 'Blasted'
The MSD and other 4 magnet types are really just designed to trigger a distributor based system in place of using the internal distributor pickup. It could not be used to trigger the ECU because there is no "missing" event to tell the ECU what the crank angle really is. You still need the distributor to direct the spark to the right place.
With a missing tooth wheel you effectively tell the ECU what crank angle the missing tooth is at, and the ECU can work out the angle of every other tooth (35 equally spaced teeth).
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