Ignition Systems Key Points & Notes Due to hydrogen’s low ignition energy limit, igniting hydrogen is easy and gasoline ignition systems can be used. At very lean air/fuel ratios (130:1 to 180:1) the flame velocity is reduced considerably and the use of a dual spark plug system is preferred. Ignition systems that use a waste spark system should not be used for hydrogen engines. These systems energize the spark each time the piston is at top dead center whether or not the piston is on the compression stroke or on its exhaust stroke. For gasoline engines, waste spark systems work well and are less expensive than other systems. For hydrogen engines, the waste sparks are a source of pre-ignition. Spark plugs for a hydrogen engine should have a cold rating and have non-platinum tips. A cold-rated plug is one that transfers heat from the plug tip to the cylinder head quicker than a hot-rated spark plug. This means the chances of the spark plug tip igniting the air/fuel charge is reduced. Hotrated spark plugs are designed to maintain a certain amount of heat so that carbon deposits do not accumulate. Since hydrogen does not contain carbon, hot-rated spark plugs do not serve a useful function. Platinum-tip spark plugs should also be avoided since platinum is a catalyst, causing hydrogen to oxidize with air

Out board engine surface gap (perma gap) spark plugs  cold rated non platinium tips

Open to models

Bosch  has this one rating of 3 cold. FR 3KI332      they also have colder 2-06 series

iridium use if possible or copper,  avoid catysts metal plugs like platinimum osrium

At one time there was a lot of excitement over another unconventional plug-nose configuration. In the " surface-fire " plug the spark gap was between the centre electrode and the flanged-inward end of the metal shell, and the insulator material filled its interior out almost flush with the electrode's tip. Surface-fire plugs don't even have a heat range; they run at about the same temperature as the combustion chamber's walls and are completely immune to overheating. Neither can they cause pre-ignition. These features were stressed at the time of their introduction, and everyone thought surface-fire plugs were just wonderful , they require  powerful, CDI ignition system.

Brand:NGK Spark Plugs
Manufacturer's Part Number:BUHW-2 S25/702
Part Type:Spark Plugs
Product Line:NGK Surface Gap Spark Plugs
Summit Racing Part Number:NGK-702

UPC:00087295007020
Shorty Spark Plug: No
Resistor: No
Manufacturer Heat Range: 12
Electrode Tip Material: Tungsten
Electrode Core Material: Copper
Insulator Type: Non-projected
Spark Plug Thread Size: 14mm
Spark Plug Reach: 12.7mm
Spark Plug Seat Style: Gasket
Wrench Diameter: 13/16 in.
Ground Strap Quantity: One
Quantity: Sold individually.
In-Store Pickup:Choose In-store pick-up (OH, NV, GA, TX) on our web site.