Saturday, September 13, 2008

Spark Plug Gap

The spark plug gap: When you read on, you can do more with the knowing the correct spark plug gap than you’d think!

Who doesn’t enjoy the performance of an automobile hugging the road; not just hearing, but also feeling the sound, the purr, of a well-tuned engine? With all the experts out there contending that the computer takes care of all that, I have encouragement for the guy (Don‘t worry I know gals are into this too!) who likes to buy their own parts, apply them and get that feeling of accomplishment that my putter has become a purr, that my thready roar has become solid and reliable. Now before I loose you and make you think that you’ll have to be knowledgeable and have many tools to make the spark plug gap be at your advantage, I’ll give you the steps you need too, don’t you worry.

Most people’s spark plug gap settings on their engine are pretty close to right, when the car is newer or when they’re first installed. My spark plug gap details will cover the scenarios where that isn’t the case. The problem is that the spark plug gap doesn’t stay right all by itself. Years ago, I was working on a dilapidated vehicle - you know most of us have had one of those - and I had enough new spark plugs for only one of my two very similar vehicles. After finishing the spark plug gaps for the newer car, it occurred to me that the older car wasn’t sounding tuned either. I checked my watch and it was too late to go to the auto store to buy more. Then it occurred to me, what if the spark plug gaps were off by a bit, or a lot. Some were 20 microns off, plus or minus, off of what they should be! Maybe I could just change the spark plug gap on the old plugs and put them back in! Those spark plug gaps, which weren’t staying gapped because of two reasons, they were a little old, and they were not made out of platinum. Most newer cars use platinum (Many ‘90 models and newer will like them). It’s tough to say which car’s engines won‘t run well off platinum, but it’s worth a try with fuel prices these days. Even back to the seventies there can be improvements made.
(9/14/15 For at least 5 years now, I've felt a lot better about iridium over platinum. Platinum now keeps it's gap about as well as copper did - very poorly. Iridium's are kind of the superior new platinum.)

Maybe ½ hour of running the engine later and some rechecking of the spark plug gaps, I realized that I needed two new spark plugs for at least two of the cylinders. They weren’t staying gapped.

I’ve since learned that platinum's gaps actually last longer and are slower to get off by as much. With out an official study it seems to me that about a quarter to one eighth of platinum’s will significantly lose their gapping within a few days of driving, depending on the manufacturer, while it looks likes 1 out of 2 or 2 out of 3 standard plugs will loose their spark plug gap in days. When the platinums are changed back at this point - when they're done being treated by being heated and cooled in the engine - they'll keep their shape much more reliably than the old standard. When checking your spark plug gaps, if the prong has kept its position accurately, there isn’t reason to change it unless there of signs of discoloration, the appearance of being burnt, or the metal is pitted.

Believe it or not, the best way to know if you’re firing evenly on all cylinders is to listen to each cylinder with a heavy metal tool. Remember to listen to your engine right after installation and once again a few days of driving later to be sure the tuning stuck! If one area sounds slower or faster, or higher or lower pitched, you’ll know that your spark plug gap is off, or your spark plug wires may need help.


Check out a video where knowing spark plug gap comes in handy.

If sparks and wires aren't enough to get that engine running smooth then you need to check out this next article telling what I learned from the Great American Jalopy, which applies to almost every car. The Great American Jalopy.

Need tuning because your car is old? Your car may be a jalopy. The jalopy is technically a dilapidated vehicle, but this article shows that it’s really the old great achievements and engineering marvels, isn’t it? Some of you really know what I’m talking about. Click above.

1 comment:

David Nichols, Night Watch Specialist said...

I've noticed that Iridium Plugs keep their gap a lot better so you're less likely to have to go back later and re-gap the plugs, only 1 of mine so far needed re-gapping. Some spark plugs determined to be gapped wrong though, so the spark plug gap needs to be changed a lot.