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

[Paul Gress <pgress@xxxxxxxxxxxxx>]

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


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