Hi All,

I have a carb'd N/A FB and I'd like to use a Microsquirt in ignition-only mode to replace the clunky distributor-based ignition with a direct-fire one using the CAS from a 2nd Gen.

I'm 90% sure I've figured out how it would work. Swap my distributor for a CAS. Install the Microsquirt inside the car up under the dash to keep it safe. Wire it out to the access board which would mount on the firewall inside the engine bay near the intake manifold, CAS, and new coils. Wire up the CAS input to the access board, wire up two of the coils to the SPKA and SPKB hookups and the other two coils to the two optional ignition hookups (ALED and WLED) with some pullup resistors. Then connect the MAP to manifold vacuum, load an ignition map, and start tweaking.

Only one problem though... Where the heck do you get an access board? I can't seem to find one anywhere! Do they make the board files available to send off to PCBWay or something so I can have one made? The vendors that carry the microsquirt don't seem to have them.

Cheers,

Jon

 

i don't know what you refer as a access board do I'm pretty sure you don't need it to wire the car.

 

The Microsquirt is intended to be mounted underhood. No need for secondary boards that increase the number of connections and therefore failure points.

Are you fuel injected? I would think that the setup you describe would increase the likelihood of flooding if you are carbureted, because the engine would be getting fuel when cranking but there would be no spark until the engine has rotated for a while until the computer can find a home tooth.

 

Not according to the manual (linked here). See Section 2.2.

I linked it in my original post, but here it is again: access board

Unlike the Microsquirt module, which the manual says isn't meant to go in the engine bay, the access board is:

The built-in MAP is nice so that I don't have to source and use a separate one.

I suppose I could mount the Megasquirt in my glovebox and just run really long wires through the firewall to the CAS, Coils, and a GM 1 bar MAP mounted near the intake manifold, but I've seen people mentioning that wiring should be kept short and shielded to avoid interference.

Nope, not fuel injected and don't plan to be. As for flooding, I've never had an issue with it, and found in my experience that people with flooding issues have issues of slow cranking speed. Upgrade the battery cables and make sure you've got a half decent starter (ie: Anything that's not the 40+yr old factory one) and there's zero flooding risk. I can literally dump raw gas down the carb into the engine and still get started no prob. In fact that sometimes happens when I take it out of storage in the spring - the needles and seats dry out so when I first prime the fuel pump it gushes some raw fuel that pools on top of the secondary butterflies until I can tap it with a wrench to reseat the needles. I dump the collected gas by opening the butterflies by hand and then get in the car and start it like usual. And that's with an old tired 12a with borderline compression! I can't imagine it'll take more than a couple rotations of the CAS to get the Microsquirt oriented, so I think it'll be fine.

If you guys aren't using the access board, what are you using to keep the Microsquirt inside the car but also have a MAP and reduce wire run lengths?

 

No need for access board.

 

Why not? What should be done instead since you're not supposed to put the Microsquirt in the engine bay? Can you provide more details about WHY there's no need for it and HOW to proceed without it?

 

I never install one with that board, and also i would keep the ecu out of the engine bay

 

I just mount my ECU's either in the glovebox or behind the stereo surround and just run all the wires out to the engine bay through a grommet like most factory cars do - at least older ones. Newer cars seem to have the ECU out in the engine bay more often than not, but the case is made for that environment.

Vipernicus - you would only have a small handful of wires to do what you want, could drill a small hole in the firewall or route them through either of the existing grommets for the factory wiring. If you don't have A/C you can use one of those holes for it. Plenty of options.

The trigger wiring most definitely needs to be shielded, no need to worry about the length though - nothing in a car wiring harness is usually long enough to worry about interference (assuming the shielding and grounds are done correctly) or voltage/current drop etc.

 

The flooding I would be concerned about is because you are effectively cranking the engine with no spark for a period of time.

May be an issue, may not. I know one way we used to get around the possibility of breaking starter noses with high compression V8s with a lot of initial timing in the distributor was to have separate ignition and starter buttons. You would crank the engine for a second or so to spin the engine up and then switch the ignition on. Otherwise a cylinder might kick right away (especially when hot) while it was still coming up to speed, and crack goes the starter.

Usually not an issue with rotaries But it also obviated some of the need to pump the accelerator before starting.

 

Thanks for all the info and feedback guys!

Alright, I'll skip the access board, mount it in the glovebox and run the wires out through a grommet into the engine bay. No A/C so as 82transam said I've got options. I'll use a GM 1bar MAP since they seem easy to get, cheap and cheerful, and are supported well by the Microsquirt.

Now to start collecting parts over the winter and be ready to get it all wired up in the spring!

 

Glad we could help 😃 I have a bunch of FC parts, sensors and coils and whatnot that I haven't used in years, pm me if you are interested.