Great tips for removing and installing your spark plugs.
While most of our customers now run diesel engines, a significant number still operate spark-ignited gas engines typically Ford Industrial, Continental, or Wisconsin. These engines are often found in lift trucks, as auxiliary engines in older sailboats, and even power generation plants running on digester gas produced in landfills. This Tech Tip, one of many we publish, deals with the care and maintenance of the lowly spark plug. Some of you may chuckle as we go over familiar ground, but please read on, it never hurts to refresh your knowledge.
Removing Plugs
First, clean out the dirt around the base of the plug with compressed air. This is important to avoid debris falling into the combustion chamber. Remove the old plug carefully from a cool head with a steady continuous pressure. Be careful not to use too much force and to keep squarely in line with the plug. Not doing this could result in stripping of threads and/or breaking the top of the plug. Once out, inspect the plug for the condition of the insulation and the color of the deposits. Wet, oil-soaked plugs are as bad as dark, soot-laden plugs. If the present plugs are going to be re-used, carefully clean the threads and apply a very light coat of anti-seize.
Have a stuck spark plug that you can’t seem to break loose? Try to old farmers trick of using a crayon. Take a few small pieces and push them down by the threads of your spark plug. Make sure they stay there for the next step. Run the engine for a little while and get it hot. The heat will melt the crayon, and the wax will penetrate down the threads and help lubricate it on the way out. The wax also won’t evaporate away or cause a bunch of smoke like penetrating oil will. This trick has saved many heads from having to be repaired by machine shops or with a thread saver!
Installing the Plugs
Use a wire type spark plug gap measuring tool. Check your owner’s manual for the recommended gap and then carefully thread in the new plugs by hand. The specifications below are a generalized list of the most common torque settings for spark plugs based on size and cylinder head composition.
|
Torque Recommendations
(pound-feet) |
||
|
Cylinder Head
|
||
| Spark Plug Thread Size | Cast Iron | Aluminum |
| Squared shouldered, | 8-12 | 8-12 |
| Gasket Type | ||
| 10 mm | 10-18 | 10-18 |
| 12 mm | 26-30 | 18-22 |
| 14 mm | 32-38 | 28-34 |
| 18 mm | 32-38 | 28-34 |
| Tapered Seat | ||
| 14 mm | 7-15 | 7-15 |
| 18 mm | 15-20 | 15-20 |
Once clean and the re-gapped plugs are back in and tight, make sure to check your wires. Ignition wires will deteriorate after a couple of years of exposure to heat, oil, grease, and vibration. New premium spark plug wires are an inexpensive way to upgrade your system. We recommend ACCELL ignition wires. They’re a favorite in the performance engine crowd and these premium wires will go a long way to enhancing engine performance, not to mention the cost when considering all the factors is just pennies more than wires you would get from big name stores.
Another upgrade worth considering is to convert from a point-style distributor to a solid-state distributor. See Tech Tip: Wisconsin & Continental Solid State Distributor Installation Made Easy for a discussion of our solid-state conversions. Finally, many customers have reported success with ACCELL Super Coils and electronic spark enhancers. If this is something that interests you, be sure to give us a call.
We hope this tech tip has been helpful. We publish this series of tech tips because we believe that tech support matters and we want to advance the knowledge base in our marine and industrial engine industry.
