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Ignition
200mph - 6/2/05 at 09:10 PM

The subject of ignition is probably my weakest when it comes to engines. Does anyone know of any good websites that describe the different types, or indeed could explain those relevant to a crossflow.

The engine I will be using is a tuned 1700 producing around 130bhp, so is there one type better than others for this?

If any of the above is a stupid question feel free to tell me, as I really am clueless

cheers
Mark


Stu16v - 6/2/05 at 10:51 PM

Are you looking for assistance on different types of ignition systems, ignition timing, or both?


200mph - 7/2/05 at 07:36 PM

more the ignition systems. Even if there are websites or books that people can recommend.

cheers
Mark


jack trolley - 7/2/05 at 07:51 PM

How to Build & Power Tune Distributor-type Ignition Systems
by Des Hammill
Quite a readable book on clockwork ignition


Stu16v - 7/2/05 at 08:19 PM

Well, there are two main groups of system - points and electronic. The electronic types can then be split into sub groups -more on that in a mo....

Points system. Satandard equipment on virtually all Xflows in standard tune. Easy to work on, dianose problems etc. If regularly maintained, trouble free. However, the weaknesses are that the points need regular attention, very regular in fact if performance is to stay at optimum. Also, points tend to be a weak spot in an engine that requires revs to make power. When the ignition timing needs to be at it's most accurate, the points are bouncing about doing their own thing, and causing timing 'scatter'. This is basically random timing alterations caused by weakly sprung points, worn dizzy shaft etc.

Electronic ignition eliminates this by getting rid of the weak link - the points themselves - and replacing it with some form of electronic trigger device instead. This means that there are no longer points contacts to burn out, and no mechanical wear casn take place, making the system much more reliable, and far better performing at high revs.

Now for the 'electronic' sub groups. The first, as suggested is merely some form of replacement electronic trigger in place of the points, and a small 'box of tricks' to convert the 'counting' into a switching current for the coil.

You can spend a fair amount of money here, with all sorts of kits offering high power systems with uprated coils etc. My personal advise is to just get a 'points replacement' kit. High energy systems are only really needed to 'fire' weak mixtures in the chase for best fuel economy, not something that will be high on the agenda if building a 130 bhp Xflow! Simple to wire in, jobs a goodun.

The second choice is a 'solid state' system, which can ultimately bypass the use of the distributor completely, the timing/spark distribution requirements controlled by an ECU. This is the ultimate way to go, as it allows the tuner to tailor the advance curve to suit the engine virtually perfectly, something that is almost impossible to do with a distributor. Kits are now available that you can 'build' yourself, probably for as little as a replacement electronic ignition system 'off the shelf' (Megajolt IIRC) if you are handy with a soldering iron. Or there are plug-in and play systems available, just depends on how much you want to spend really. Definately the best way to go in turns of tunability...


200mph - 7/2/05 at 09:20 PM

excellent - thanks for the replies!

cheers,
Mark


NS Dev - 7/2/05 at 10:36 PM

really good summary there by Stu!!!


Stu16v - 8/2/05 at 07:17 PM

Just bloody glad 200mph didn't ask about ignition timing...


200mph - 8/2/05 at 07:28 PM

so.. ignition timing huh... whats that all about??



go on... you know you want to. People like showing off how much they know

cheers
Mark


Peteff - 8/2/05 at 09:12 PM

Set your ignition before 8.00pm, that way you'll still have time to go out for a pint.


Rob Lane - 9/2/05 at 08:13 AM

Cheapest, simplest way to upgrade ignition on a Xflow is to replace dizzy with an electronic Bosch item from a Valencia engine, about £30 from a breaker.

Drop in fit, time up, forget it. Makes engine smoother instantly, it can really be felt.