Spark Plug cleaning

[Flatiron]

I'm Using NGK 10 R8102A-10 in my 302. Seeing that these plugs are both pricey and hard to come by I'm looking to clean mine. Whats the best way to do this ?

[Yellowjacket]

It depends a lot on what is on the plugs and how you're using them. We've been running a 2 stroke motor on jet fuel and plug fouling was one of our hugest issues. Since plugs were $12/plug and we were going thru a half a dozen a day in the early testing we developed a way of cleaning them that appeared to work pretty well. Our problem was carbon fouling from the jet fuel and the nasty oil we are using, and racing engines generally run hotter, but here is what we did. If you're running a lot of oil that could well be the biggest issue since some oils have a lot of heavy metals in them.

First forget the sand blasting cleaner. It worked, sorta, for a while, but in our case it didn't really clean the center insulator well, it didn't get down into there and clean the crud out.

What we learned is that you need a good chemical cleaner that removes carbon as well as the heavy metal deposits on the center insulator if you want a plug that works for any period of time... We developed a protocol for cleaning plugs and here it is.

First we use a shot of Brakeclean to get any soot off of the plug. Second is put the plug spark end up in a rack and use a syringe to fill the plug up with Berrymans carb cleaner and leave it there for two days. If it starts to dry come back at the end of the first day and make sure you top it up again. After it has soaked for 2 days use Brakeclean again to clean the plug out. Finally put the plug in an ultrasonic cleaner and twist it around until you can see the last bits of carbon coming off of the center insulator.

Probably other ways to do it, and if you had some Turco that might even work better (we used Turco on turbine engines to get oil deposits off of baked on areas), but this has worked pretty well for us.

The last thing is what fuel are you running? Leaded fuels are horrible on spark plug life and if you're running a leaded fuel you will likely need to get a spark plug sand blaster to get the final deposits off of the plug. Lead fouling on spark plugs is a result of running too cold a plug and the lead deposits don't burn off. On an engine like a Yamoto, the compression ratio isn't that high and detonation isn't an issue. If you're running avgas or a leaded racing fuel you're going to have really short plug life. Aircraft run their plugs a lot hotter, (engine are air cooled and the engines are running lean at high power) so they keep their plugs hot and they don't foul as quickly. An outboard, even in a racing setup isn't running the plug temperatures like an aircraft, so they aren't going to keep the plugs hot enough to keep them clean. The answer to that is to go get some unleaded fuel without ethanol in it and use that instead of the leaded fuel and your plug life will increase significantly.