OK, the current thread on spark plugs "Autolite plugs and wires" in the 3.0L Forum has got me wondering about a few things.

Why is a spark plug gap so vital to engine performance? How does it get calibrated? By that I mean, how does Ford determine what gap a certain plug will have in a certain engine?

Related question: Is the spark bigger and more intense with a wider gap?

Any insight and/or feedback would be appreciated.

 

Maybe start here with your read.

http://tpub.com/basae/43.htm

I know there are many variables involved.

 

The factory selects the gap based on performance AND longevity. You can open the gap up to create a larger spark for better combustion, but it puts more strain on the system to jump the gap. This means you have to change the plugs more often, and the wires, rotor and cap all have to be in top condition. If you make it harder for the spark to jump at the sparkplug(wider gap), then it's more likely to jump through bad wires and dist caps, causing missfires.

 

Hey guys, thanks for the feedback!

Dennis...very good link...has a lot of good info on plugs & ignitions systems in general.

Dave...everything I've read so far says you are right on target about the connection between the gap and the required voltage and possible problems that may come from the wrong size gap.

You guys are both right about the various factors that go into determining the right plug and gap size in relation to required voltage. Here are some graphs bearing that out:



Also, here are a few more links I ran across with decent plug and gap info:

Spark Plugs Overview

Spark Plugs Tech Paper1