Re: [DML] Re: Stock Ignition vs HEI Ignition

[Paul Gress <pgress@xxxxxxxxxxxxx>]

On 07/ 9/12 07:51 PM, jtrealtywebspannet wrote:
> There is another problem with modifying the ignition in the Delorean. If you are not careful and mismatch the coil too much you will burn out the ignition Module. That can't happen with a set of points. The other limiting factor is the cap and rotor. As you go higher and higher with the voltages you approach the break-down point of these stock parts and there is no performance substitute. The purpose of the higher voltages is to be able to run leaner mixtures but also to be able to jump over a wider range of gap. The rule-of-thumb is about .001 per 1,000 miles. As an example if you start with .035 and drive the car 10,000 miles you can expect the gap to grow to .045. In order to increase the time between spark plug changes they increased the voltage so you can run wider gaps and also improved the metals used in the spark plugs so they don't wear as fast. That's why you see multi point grounds and platinum electrodes. Now you can run a set of plugs 100,000 miles! As for bigger spark,
>   the voltage increases up to the point where it can jump the gap. Even if you have 100,000 volts it will only get to what it takes to jump the gap on the spark plug and no more. All a spark plug is is a match. You can start a small fire or a big fire from a match, the match does not determine the size of the fire. Once the mixture is ignited it propagates without any regard to how it was started. It is an area of marketing and misinformation full of products of dubious value.
> David Teitelbaum
>


Right, I fogot about the distance between the distributor cap electrodes.  If to close, they will crossfire as the voltage increases.  The HEI ignition distributors had a larger diameter circle for the electrodes to increase the spacing between them.

Also, remember, a spark plug is a voltage regulator.  The extent of the voltage created is the maximum just as the spark jumps.  This means, if you have a coil capable of producing 30,000 volts, and the spark on the sparkplug jumps at 10,000 volts, that all the voltage you used.  You never reached 30,000 volts.  This is why you need to increase the sparkplug gap to make any improvements, which with a stock distributor is useless.

Paul


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