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breakerless ignition and microsquirt q's

makebrickgovroom

New member
Joined
Apr 15, 2020
Location
Colorado
Its me again. Brain is small and hard. I copped an lh2.2 dizzy from swedishiron (big thanks) and am now brainstorming the removal of the stock ignition.

So, the ignition amplifier:
- white to coil
- blue to ballast resistor, blue to fuse box
- brown to ballast resistor
- brown to starter

Plan is to remove everything except resistor and starter connections. Any potential problems with this?

I'm really struggling figuring out the fuel relay wiring for microsquirt. I fear that i'm overthinking it but I also don't want to royally **** something up. My thought is:

- red wire from stock relay for 12v
- blue/red for 12v switched
- output to conjoined yellow/red fp wires
- output to fuse block

Any major flaws with this? Do i need an in-line fuse (20amp) for the 12v?

Also, I would like to have a tach when's all said and done. the two white/red wires (one from coil and one going to tach) would be the way to do this, correct? Here's what i'm thinking:
- white/red from tach is power output. seems redundant now with microsquirt. remove
- white/red from tach --> tach output on ms

I've read conflicting information about whether or not you can directly wire the tach output to the tach -- some say to use the tach relay trick, others say it works fine without. Which to do??

Many thanks!
 
It will be easiest to replace all the original K-Jet relays, fuses and wiring with new ones. Follow this diagram as closely as you can, and ask questions if it doesn't match what you're seeing: http://www.msextra.com/doc/pdf/html/Microsquirt_Hardware-3.4.pdf/Microsquirt_Hardware-3.4-15.html

I'd mount the 2 cube relays on the original ignition coil frame, and find a good sealed fuse box to mount nearby -- there was a thread about this somewhere in the last year.

For ignition, you don't need the ballast resistor -- microsquirt won't leave voltage on the coil without the engine turning. In old pre-computerized ignition setups, the ballast resistor prevents frying the coil with key on, but not running, when the points just happen to be closed where the engine stopped. You will need an ignition module, or power stage, to use the microsquirt. A standard Volvo LH2.2 or LH2.4 one is fine.

Since your tach was originally driven by a red/white wire to the coil "+" terminal, you can just wire it that way again with MicroSquirt. You only need the dummy relay when changing to wasted spark (2 wires from microsquirt), or full sequential spark (4 wires from microsquirt).

For a 3-pin LH2.2 Idle Air Valve, you'll need a power resistor from one side to ground - 40ohm 50watt works, but others should too. If you use a 2-pin LH2.4 IAC, you don't need the power resistor.
 
It will be easiest to replace all the original K-Jet relays, fuses and wiring with new ones. Follow this diagram as closely as you can, and ask questions if it doesn't match what you're seeing: http://www.msextra.com/doc/pdf/html/Microsquirt_Hardware-3.4.pdf/Microsquirt_Hardware-3.4-15.html

I'd mount the 2 cube relays on the original ignition coil frame, and find a good sealed fuse box to mount nearby -- there was a thread about this somewhere in the last year.

For ignition, you don't need the ballast resistor -- microsquirt won't leave voltage on the coil without the engine turning. In old pre-computerized ignition setups, the ballast resistor prevents frying the coil with key on, but not running, when the points just happen to be closed where the engine stopped. You will need an ignition module, or power stage, to use the microsquirt. A standard Volvo LH2.2 or LH2.4 one is fine.

Since your tach was originally driven by a red/white wire to the coil "+" terminal, you can just wire it that way again with MicroSquirt. You only need the dummy relay when changing to wasted spark (2 wires from microsquirt), or full sequential spark (4 wires from microsquirt).

For a 3-pin LH2.2 Idle Air Valve, you'll need a power resistor from one side to ground - 40ohm 50watt works, but others should too. If you use a 2-pin LH2.4 IAC, you don't need the power resistor.

Ha, that's the best friggin diagram I've seen in the past month. Major props.
Microsquirt has auto dwell control, correct? If not that'll sway me to purchase a 139 module.

So here's what I'm thinking:
- splice 12v to pin 30
- splice 12v switched to pin 86
- 87 out to new fuse panel --> 15amp to fp (here's where I have a question: would I wire both yellow/red wires, or omit powering the one currently connected to fuse #5 in the stock box?)

and that's about what I've got. not too grandiose and pretty much verbatim to the manual, but "talking it out" really helps me understand what I'm doing.

I see the main relay is intended to power microsquirt, but the fuse block I have is centrally powered. It doesn't seem logical to wire both relays to the block, and the best solution I can come up with is an inline fuse, which seems messy. What are your thoughts?
 
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