On Fri, 16 Apr 1999 xyzabcde@earthlink.net wrote:
> Hi all,
>
> I tried splitfires once in my '67B and the car suddenly barely ran. The plug
> ads claim that there is more spark from more sparking area on the plug. But
> electricity follows the path of least resistance--the spark will only jump
>from
> one point. So, as far as I can tell, the split in the plug just makes it
> impossible to gap the thing correctly since it's impossible to tell where the
> spark will start.
>
> Any of you engineers out there care to correct my uninformed assumptions? ;-)
>
> Denise Thorpe
As far as I can tell, you're right. The only thing that might make
modified plugs spark "better" than regular old ones is that sparks jump
better to/from points then large flat surfaces. Of course, points wear
down faster than thicker parts, causing the gap to change. So, spark
plugs are designed as a compromise.
Having two points is only helpful if one gets fouled (with oil, say) and
the other doesn't. RX7s use unusually-tipped plugs since the oil to lube
the rotary seals is injected into the combustion chamber directly. They
have four outer (base) electrodes and a recessed tip.
--
John M. Trindle | johnt@tsquare.com | Tidewater Sports Car Club
'73 MGB DSP | '69 Spitfire H Stock | '88 RX-7 C Stock
|