Re: Ignition and sparks

[Barrie Robinson <barrie@look.ca>]

Theo,

Thanks for your input - Very interesting !!!


At 11:05 AM 1/29/06, Theo Smit wrote:
> MSD does two things. First, below 3000 RPM you get multiple spark events, 
> which is helpful in preventing misfires and the resulting plug fouling. At 
> high RPM, the high coil primary voltage (up to 300 or 400 volts) saturates 
> the coil even though the time between ignition events is drastically 
> reduced. Conventional coil drive systems lose most of their fizzle at 
> higher RPM, and this can lead to high speed misfires. I'm not saying that 
> they are a cure-all, and you are correct that without a good timing 
> reference the battle is lost from the outset, but the MSD systems and 
> their ilk do provide useful benefits besides the big decal. A system like 
> the MSD6AL also includes a rev limiter, and if you're at all interested in 
> running your car in track or autocross events, then a rev limiter is an 
> absolute must.
> You can use the optical sensor from the Allison system to trigger the MSD 
> input as well, and get the benefit of more reliable ignition triggering 
> plus the improved coil firing that the MSD offers. No sense in going halfway...
>
> To answer Barrie's comment - the problem with ignition is that the typical 
> engine cylinder is not a big room filled with an explosive mixture - it 
> has rich spots and lean spots all swirling around. If the coil fires when 
> there's a big glob of fuel hanging on the electrodes, it won't fire the 
> plug... and it also won't fire if the mixture at the plug, at the firing 
> instant, is 25:1. The multiple spark business gives you better odds, and 
> it does actually work. You just have to decide whether or not it's worth 
> the $130 or more to get it, and I do agree that if you're on a budget, 
> then fix your distributor first, and install an Allison, Pertronix, GM, or 
> other points replacement trigger and amplifier.
>
> Best regards,
> Theo Smit
Regards

Barrie Robinson
barrie@look.ca 
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