by Lorne Goldman

Spark plugs are simple things. People wax eloquently forever on which one to use. However, that is a waste of time. That being said, a bad match might not light it and some plugs types will last longer than others.  For this reason, spark plugs should be checked and changed regularly. Over time the spark plugs electrodes will wear, chnaged the all important gap that shapes the spark. Over a long period, if not changed the spark plug threads will fuse with the motor threads. This will often strip the motor's threads requiring a helicoil (if you are lucky) or a new engine head (s).

Installing and removing plugs are a trick as well. If you use the wrong tool, the possibility of breaking the plug is very high. The proper tool is called a spark plug socket and they come in sizes that match all spark plugs types. They are made for this task and have a foam, silicone or rubber insert that protects the plug from shattering. They look different in Europe so I have provided a picture of both types.

I carry one in my Morgans. Other spark plug questions are addressed in the Ignition Section. 

Spark Plugs and Power
by NGK and Lorne Goldman

From the NGK site.  "A common misconception is that changing spark plugs will result in a large power increase. In most cases, removing even seriously worn out spark plugs will only result in very modest power gains, typically about 1-2% of total engine output. This could be even less for computer-controlled vehicles, primarily because most newer vehicles have more powerful ignition systems and the vehicle's computer can make adjustments so that vehicle operation seems smoother and more seamless.

Many people think that simply supplying more spark to the firing tip can and will combust more fuel. What they don't understand is that most newer car engines are so efficient that they are already burning all of the available fuel. Simply adding more spark voltage can't burn more fuel because there is no more fuel to burn.

When a stock or near-stock engine is given a fresh set of spark plugs, peak efficiency is restored. The power gains that come from this restored state of tune are usually minimal. Any company that tells you that their spark plug will provide significant gains in power in a stock or near-stock engine is making blanket statements that may not be supportable."

WATCHPOINT: How true! Any tales that someone tries to sell you to the effect that a spark plug, of any type or cost, can increase horsepower is bunk. That is analogous to asserting that a better match will create a bigger bonfire. One has nothing to do with the other. A better spark can steady or restore your engine running to its production ideal, but nothing more (and that is more than enough to justify the purchase of the best spark plug!). Power is a function of other things.

A Morgan Spark Plug Holder
by Einar Aagotnes   

For a good deal of space saving and ease of access this spark plug holder was fashioned and attached to the bulkhead tool box.

Checking for a Spark
by Lorne Goldman

Remove a plug wire and insert an old spark plug  into the end of the wire (the plug boot). Place the spark plug on a metal surface on the engine. Then crank the engine to check for a spark. No spark indicates an ignition problem. It is best done with two people as the spark is very faint and blue, a bit hard to see, especially in the light. A darkened garage makes it easier for one person to see it.