WORK SHOP BASICS Petrol ignition timing

MODELS: All early petrol models.

TOOLS: Spanner for distributor clamp, multimeter, timing light, spark plug socket and ratchet, feeler gauges.

WORK SAFELY

• Ignition systems use high voltages. Never handle live leads with a running engine, use correct insulated pliers.
• Never replace ignition components with a live ignition system. Turn it off, or disconnect the battery.
• Beware of moving pulleys, fans and belts on a running engine, keep fingers, tools and clothing away.
• Never rotate a crank with a live ignition system — remove the distributor cap to prevent engine starting.
• Never run an engine in an enclosed space, always ensure the exhaust is piped safely away.

THANKS TO: Powerspark, simonbbc.com

WHICHEVER petrol engine you have in your traditional Land Rover, it needs to be timed to work correctly. By timing, we’re referring to setting the point of spark against the optimum position of the piston in its cycle. Though you may expect it to be the same point for all engines, you’d be wrong. Each engine has its own setting, dictated by the time it takes for the fuel to ignite fully, when the piston is in the right place to maximise the energy from the bang.

That point isn’t at the top of the stroke, a position of the crankshaft termed Top Dead Centre (TDC). Instead, it is before that point, calculated from knowing