by 1972nail » Wed Jul 31, 2013 11:07 am
The resistance wire on the standard ignition is bypassed during cranking to provide extra voltage to the coil and a fatter spark when starting. The fatter spark isn't really needed during normal road driving on light throttle so the resistance wire comes into play to reduce overall coil temperature and better reliability - in theory anyway!
On the 2300 electronic has been tested in the past and shown to provide increased BHP, particularly on higher compression heads, probably due to the standard spark being suppressed on wide open throttle and high engine loads.
So.... The electronic ignition should provide the fatter spark all the time so a normal 12v coil could be used without the resistor but be careful not to overheat the coil and put it in a cool location in the engine bay and / or carry a spare good coil - just in case!
Years ago my brother and I fitted Mobelec ignition to a 1256, we also fitted a 12v Lucas 'Sports' coil .... Disaster! We didn't know about the resistance wire until it burnt through the loom! The coil increased the load on the resistance wire causing it to overheat and set the car on fire! So I'm not a fan of retaining the resistance wire in any case. Mike's suggestion of a separate resistor is a much safer option in my opinion.
Bypassing the wire and fitting a normal 12v coil will not increase the spark strength if the standard points are retained at all. So starting from cold could be a problem as you have only got the weaker 'normal running' spark strength during cranking. The resistance wire setup provides the equivalent to about a 15v coil for cold starting and a 12v coil for normal running.
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