Correct setup for crab style distributor

The total primary resistance has to be high enough to reduce current over the points or they will not last long.
With 1-1.27 i would add the external resistor.
 
Bluebell, 10 out of 10 for your explanation of the original Ford V8 ignition resistor and coil. There are a lot of explanations put forward about this very simple system ,most of which are incorrect. The .5 ohm Ford 18-12250 wirewound resistor is made from a special resistance wire and is designed and matched to go only with the original Ford V8 Bakelite ignition coils and NO OTHERS necessarily. Apart from overcoming the problem of the starter motor dropping the battery voltage whilst cranking the engine, and robbing the ignition coil of voltage the resistor also controlled the coil supply voltage and current at low and or higher engine RPMs. The distributer contacts opened and closed slower or faster depending on the RPMS of the engine and thus had the effect of the coil current draw going down and up as well. The resistors resistance increased and decreased with the varying current flow through it and there by evening out the performance of the ignition coil and protecting the primary windings from overheating at slower RPMs. Its only a simple resistor but understanding its several functions is sometimes difficult. Best to always use the original FORD part and not the reproduced ones which can vary quite a lot in their build quality and performance. Regards, Kevin.
 
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