M20 Carb Ignition

[knapmann]

Hi Guys,

I am building a 2.8 M20 with Triple 44 Weber IDFs, it is going into my '02. I am wondering what my options are for the ignition system. The engine is a 1.3 Motronic 1989. I assume I have 2 options and I have lots of questions.

1) Run a mechanical block mounted distributor from E21/ E30

There are lots of M20 distributors with different ignition advance curves (ranging from 16-34 degrees at 5000rpm) - which is best for a street performance engine 2.8? What kind of advance do people run at 5000rpm?

2) Splice in the E30 loom and run ECU controlled ignition via tuneable stand alone or chip. This takes a lot more effort and money.

Will the ignition system work with no TPS, injectors, and no AFM etc? or does it need signals from these sensors to actually fire? I assumed it just fired off the crank sensor...

3) Maybe there is some other distributorless ignition system I don't know about

I am leaning towards option 1 unless I am unlikely to find a distributor with a decent advance profile. There must be people on here running street tuned, maybe stroked engines using the block mounted distributor?

TIA!

[Brianmoooore]

The motronic ECU will happily work the ignition in the state you describe. The lack of AFM will allegedly affect the advance curve slightly, but I know from experience of LPG power M20s with locked open AFMs, that the effect is minimal.

[knapmann]

The motronic ECU will happily work the ignition in the state you describe. The lack of AFM will allegedly affect the advance curve slightly, but I know from experience of LPG power M20s with locked open AFMs, that the effect is minimal.

Hi Brian,

Thanks for the reply, I have been told that without a TPS the ignition will stick in the "idle map" and not advance properly when the throttle is engaged? What do you think?

Thanks!

[Brianmoooore]

Without a TPS it will stay on the normal 'run' map. It would need two of the TPS wires shorted together to switch to the idle map.