Spark plug discussion***Split from engine car reassembled thread***

[Ron]

The ignite will only journey across one of the prongs and not all four.

True...the spark will jump to the closest electrode. But it will erode and the spark will jump to the next longest, and so on... They just last longer.

[Bill Robertson's Sock Puppet #1]

It is extremely difficult to change multi electrode plug gaps, which does rule them out for certain custom ignition setups.

[David T]

If you compare the cost of the plugs and consider the mileage most of us put on our Deloreans it doesn't make economic sense to spend the extra coin on the more expensive plugs. There is no improvement in performance or gas mileage. Who needs a plug that can last 100,000 miles in a Delorean?
David Teitelbaum

[Kenny_Z]

After this:



I'll stick with traditional plugs in all my vehicles. I did have an issue with a head gasket leak in that cylinder but I've read that this is a common problem with this type of plug. You can see the traditional plug is just as dirty when I pulled the head but not cracked or broken after more miles.

[sdg3205]

If current trends continue it will be 2082 when i hit 100k miles.

[Ron]

fwiw, I wasn't suggesting to use the multi-prong plugs, just explaining the idea behind them...

Delorean or not, if the engine is stock, you are almost always better off to stick with the plug the manufacturer calls for. Why toss all of the manufacturer's re$earch out the window when they want performance just as much as we do? (Emission/mileage requirements wouldn't force the use of a different plug. Look at an old chart when they had a free hand -- sometimes the same plug was used from I4 thru V8.)
Same thing goes for any of the ignition components. Change one, and you change the characteristics of the burn. ...And even if you tweak things for a particular engine, if you get your fuel from a local gas pump, you wasted your time.

Bosch HR 6 DS
Word.