Rotating spark plugs

[az'03Silverado]

Just a thought. I've learned a lot this past year as I've been in school earning my A&P aircraft mechanic's license. Some of you may know that aircraft piston engines have two spark plugs per cylinder. Well, during periodic inspections of the engine the plugs are pulled, cleaned (vibrated and media blasted) and reinstalled. When reinstalling, the plugs are rotated to the next cylinder in the firing order and from top to bottom or bottom to top. This ensures that the spark plugs will wear evenly and keep the engine performance regular.

My question is, does anybody think that this would be beneficial for automobiles or just a waste of time? The reason the plugs on airplanes are cleaned and such is that they are about $20-50.00 per plug and multiply that by 8 or 12 and it gets pricey. Car plugs are relatively cheap so they can be replaced more readilly.

What do you guys think?

[C & A s Dad]

If I am going to pull them out, I am putting in new ones. However, if they cost $50 a piece, I think I would be rotating them.

[Black02Silverado]

Good question! I have read that your suppose to keep the same spark plug to the same cylinder if you pull them out for any reason. Not sure why. Each cylinder has it's own characteristics in the way the combustion takes place. Not sure if the spark plugs adjust to that or not and if rotating them would make them more or less efficent. I don't see why it would. At least on ground transportation if you have a problem you can just pull over to the side of the road. Kind of hard to do that when your a few thousand feet in the air.

 

It is amazing on what gets reused in aviation engines. Taking out the cam and lifters inspect, clean and reinstalation I found interesting since again on an automobile those get tossed for new ones. I agree price is a major factor.

[uh6077]

I have a KZ1000 street/drag bike. I sandblast those plugs often. I run high compression and biggers carbs. The plugs get dirty after some hard runs (spanking plastic crotch rockets). I use racing plugs and they are like $3 a piece. Still cheap but I would be buying them about every 2 weeks. I just blast them. Make sure there is no media left in the plug though.

[rjirvine]

As a fellow A&P I know exactly what you are asking. Plugs on the bottom will get fouled faster than the top ones, so after cleaning them etc. it makes sense to rotate them to the top. Continental recommends rotating them every 25-50 hours...try that on your truck...Yikes!

 

Since there's only one plug per cylinder on our engines, and it's on the side I don't see any benefit to rotating them. I just replace 'em.

 

Here's more on the topic:

 

http://www.lycoming.textron.com/main.jsp?b.../whyRotate.html

[az'03Silverado]

Thanks for the replies everybody. I didn't really think it necessary on an auto engine but I wanted to throw it out and see what everyone thinks. Thanks for the article Bob!