Yes, you should rotate your spark plugs every 100 hours. This will help even out electrode wear caused by constant polarity and capacitance after-fire. Place them in a Tempest spark plug tray (P/N T240) and follow the rotation guide supplied on every Tempest spark plug box.

Typically Tempest spark plug resistors will stay between 1000 and 1500 Ohms throughout their life. Tempest specifies that the plug resistor should never be below 500 Ohms or above 5000 Ohms. We offer a lifetime guarantee on our fired-in resistor.

Carbon fouling is indicated by dry, fluffy, sooty deposits. The plug is operating too cold to burn off combustion deposits. This may be fuel related or ignition related. Fuel related causes include rich fuel mixture, faulty carburetor adjustment, excessive idling or improper idle mixture. Ignition causes could be related to a worn spark plug ignition lead, improper magneto timing or running too cold of a spark plug.

Indicated by hard ash-type deposits, lead fouling can be caused by poor fuel vaporization due to cold operating temperatures or high-lead content in the fuel (misdistribution of tetraethyl lead). Lightly fouled plugs can be cleaned, re-gapped, tested and reinstalled using a new copper mounting gasket. Severely fouled plugs should be replaced with new Tempest® spark plugs.

Oil fouling is indicated by oily, wet deposits and frequent misfires. Causes can include damaged pistons, worn or broken piston rings, worn valve guides, sticking valves, faulty ignition supply or an engine during break-in period.

Please visit the Technical Data portion of our website to find our articles on best cleaning practices.

Tempest currently manufactures only 18mm spark plugs.

Please refer to the Tempest application chart. There are several things you will need to know as most engines have several different spark plugs approved.

1. You will need to know your harness B-nut size. This is the nut that screws onto the spark plug. It will be either a 5/8-24” or ¾-20 thread. Be aware that a 5/8-24 utilizes a 3/4” wrench and a ¾-20 utilizes a 7/8” wrench.
2. Long reach v. short reach will be determined by the specific engine.
3. Heat rating is indicated by the numeric value of the spark plug part number. The lower the numeric value the colder the heat rating. Best practice is to use the same heat rated plug you have removed.
4. Massive electrode or fine wire is a personal choice. Massive plugs will generally operate 400-500 hours. Fine wires can last 1500 hours. This choice is usually determined by number of annual hours flown and the size and performance of the specific engine.

Yes! FAA STC was issued in July, 2023.

The SIM is compatible with all automotive and aviation spark plugs. SureFly’s FAA STC’s do not grant permission to use automotive spark plugs in FAA certified engines. You may only use spark plugs FAA-approved for your application.

The SIM outputs a 60Vdc spike with a 10Vdc offset on the p-lead (2 pulses per rev for 4 cylinder models & 3 pulses per rev for 6 cylinder models).

The SIM is turned on and off with the existing ignition switch through the p-lead wire connected to the p-lead terminal of the SIM.

SureFly recommends replacing the impulse coupled magneto. This is to reduce the possibility of impulse coupler mechanical failure and also to help the engine start better.

The SIM is a solid-state ignition module with the benefit of improved reliability and zero maintenance (no rebuilds & no overhauls) over the lifetime of the SIM. Another benefit is improved starting.

SIM4P - 4.4 lbs.

SIM4N - 4.0 lbs.

SIM6C - 5.0 lbs.

SIM6L - 5.2 lbs.

Return the SIM to SureFly for evaluation after 2400 hors of SIM operation.

1. SureFly Ignition Module (SIM)
2. Power wire harness (84" long 14ga. wire with inline fuse holder, 10A fuse & ring terminals) If your battery is located in the tail of your aircraft, you will need to purchase a longer power wire.
3. Manifold pressure hose (36" long 1/8"ID x 1/4"OD high temp. rubber hose)
4. Engine STC paperwork
5. Airframe STC paperwork

Absolutely! Compared to a magneto, the SIM provides a more accurately retarded spark and a more consistent, higher energy spark at low engine RPM. Hot-starts are greatly aided by the installation of a SIM, but keep in mind SureFly can’t remedy fuel system shortcomings!

State regulations require sales tax to be collected unless certain exemption forms or information is received. Sales tax is calculated based on the state and jurisdiction shipped to. Some states have specific general aviation tax exemptions and require shipping charges to be included in sales tax calculation. Sales Tax Exemption Wizard

Use a straight edge as seen in Figure 1-3 to see if it's bent.