1989 318 TBI ignition questions
will the original ignition function properly?
AFAIK that 89 is a LeanBurn with NO V-can and a fixed rotor. The Vcan you see on the air-cleaner is a load sensor. It tells the ECU how hard the engine is working. Together with the Rpm sensor, The ECU determines how much timing it's gonna let the engine have. and it's never enough.
So while the OEM LB computer will run your engine ,
the only way you can tune that thing is if you can change the timing curve, so your D needs to have flyweights in it and a Vcan. Otherwise what's the point of installing the 4bbl? With retarded timing, it will still be the dog it always was.
The LB system is pretty relaxed about timing and is one of the reasons those engines are also pretty laid back.
But if your 89does not have a LB, then you still need an adjustable D and stand alone ignition system. As for a coil, I highly recommend the Accell big square top, with it's recommended ballast; it will fire anything at any gap all the time and mine was new in 1999, and it won't burn off your plug electrodes. My plugs were new in 2004 IIRC. Cheapest coil, in the long-run, I ever bought.