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The advantages and disadvantages of an electronic ignition are pretty independent of the fuel injection system. I really like them because they don't wear, I set the timing on mine (Crane XR700) and if I check it 5000 miles later it's right where I left if. Not so with points, that little rubbing block wears, the points erode, it changes from the moment you put it on. If you have modified the motor and drive it hard, you might benefit from a more powerful ignition system, as the peak pressures rise in the cylinders, the resistance across the plug gap rises, and it takes more juice to make a good spark. It's a bit more concern to forced induction motrs, but a weakened original coil will start to show problems even on a stock motor.
There's no doubt that fuel injection does a much better job at feeding the engine the fuel it needs. But there are tradeoffs. A set of SU's are dead simple to toss on, and they'll do their 'pretty good' job with no hard thought required. Develop of feel for the art (it isn't science for sure) of balancing and tuning them (seasonally) and they can be pretty decent.
D-Jet - the electronic fuel injection of the early 70's, is pretty primitive, and lacks adjustability and adaptability. It has no feedback mechanism whatsoever, so if you modify the engine (or it simply wears a bit) it can't tell the difference, it just sticks to its hardwired fuel map. In general terms on a stock motor (2 liters, D cam) it does a better job than carbs. Although typically it seems to use a bit more fuel. It gets a bad reputation because it is electrical, and when 'tinkered' with by mechanically minded mechanics it doesn't respond well. it is best approached from an electrical standpoint, the few mechanical aspects of it (like the fuel pump and pressure regulator) should not be messed with in attempts to band-aid electrical issues (like a bad wire or sensor).
To really get closer to the holy grail of clean running, max efficiency, and max power, you need a newer fuel injection system, one with feedback so it can adapt to changes in the operating conditions, fuel, and motor. Megasquirt is a neat cheap system. It's a modern fuel injection system that is completely programmable and open, unlike the sealed (literally) box that most OEM computers are, including D-jet. It's just the controller, you'd use it with fuel injection hardware of your own devising, but D-Jet hardware is a great start - you can re-use almost all of it (new throttle switch and pressure regulator (manifold pressure referenced), pitch the troublesome 'hand grenade' D-jet pressure sensor. You just install it, wire it to the car, and program it using a serial cord to a PC (laptop is very handy). The good news is that you wouldn't be a pioneer, you could probably get useable fuel maps from other people who have already done this to their Volvo B20's. Add an O2 sensor for feedback, and this can even run the ignition advance (based on MAP and RPM) if you add an extra ignition box like an MSD 6 and lock the mechanical advance on the distributor.
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I'm JohnMc, and I approved this message.
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