The Champion UL77V, stock number 831, is a surface discharge marine plug. Like the QL76V it fires across the insulator nose to the shell rather than across a side electrode gap, which is the configuration two stroke outboards use to survive oil-rich running without fouling out. There is no gap to set and nothing to bend.
- Do not attempt to gap it. Champion publishes no gap figure because the surface discharge design has none.
- Non-resistor plug. That matters: fit it only where the engine builder specifies a non-resistor type, since resistor and non-resistor plugs are not freely interchangeable on modern ignition systems.
- 14mm thread, 13/16 in hex, 1/2 in reach, gasket seat, solid terminal.
- Copper core center electrode for conductivity and heat control.
- Resists fouling and overheating under heavy engine loads.
Check the engine manual before fitting. Heat ranges do not translate between plug manufacturers.
