Small update, the engine is in the car and it's running very nicely (covered 150km ), however it's still detonating and I can't figure out why (timing is down to 19 degrees at 0.5 bars and AFR is ~ 11.8). I'm starting to suspect the Megasquirt setup (ignition part). Bad news is that something in the clutch broke Sunday so these days the gearbox has to come off, hope there is not a lot of damage. Btw does anyone have an idea of how I can measure the ignition timing with the timing gun while driving the car (i.e. under load) ?

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190E 3.0-24v (M104 980) turbo @ 0.8 bar
1/4 mile: 2.483 / 13.540 / 175.17 km/h (street tires)