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



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 

--- In dmcnews@xxxxxxxxxxxxxxx, Paul Gress <pgress@...> wrote:
>
> On 07/ 9/12 04:08 PM, Stephen Rice wrote:
> > People seem to bash HEI on Deloreans for some reason.  Here is a
> > little information I found out regarding my Mustang and HEI.
> >
> > The stock plug gap for a 1965 Mustang is between .032 and .036 (very
> > similar to a Delorean).  When I bought my Mustang the previous owner
> > told me it was idling poor.  Upon checking the spark plugs I found
> > they were gapped around .05 yet no one bothered to increase the
> > ignition going to them.  I put in some new plugs that were properly
> > gapped to .032 and the car seems to idle fine.
> >
> > Upon further investigation I found that one very common mod in the
> > vintage Mustang community is to upgrade to HEI.  Basically you put in
> > a Duraspark II distributor and ignition module and then bump up your
> > plug gap to .05.  My question is, if this is so commonly accepted for
> > a vintage Mustang, why is it so bad for a Delorean?
> >
> >
> 
> Steve, it's not bad for a Delorean, just not required.  Having a higher energy spark does not ignite the fuel any different.  It serves only one of two purposes.
> 
> 1) Increase the time between spark plug changes, assuming you never increased the gap.
> 2) Ignite leaner fuel mixtures.  This was required in the 80's as manufacturers tried to reduce gas consumption.  But just not leaning out an engine will result in increased fuel efficiency.  You engine will start to detonate prematurely due to higher combustion temperatures.  The car manufactures adjusted this with a exhaust gas recirculation (EGR) valve, whereby it recirculated some exhaust gasses back into the combustion chamber which slowed down the flame travel and reduced the combustion temperatures.  Unless you can properly adjust your engine for leaner fuel mixtures you will not gain any performance.  Adjusting your timing will negate any improvement.
> 
> I hope this helps.
> 
> Paul
> 
> 
> [Non-text portions of this message have been removed]
>




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