The ignition system used in HK, HT and HG Holdens is relatively simple in design but plays a critical role in overall engine performance. When ignition components become worn or incorrectly adjusted the engine may develop a variety of running problems including hard starting, misfiring, poor fuel economy or lack of power. Understanding the symptoms associated with ignition faults can help identify the cause of a problem before unnecessary parts are replaced. The following troubleshooting guide outlines common ignition system problems and their likely causes based on the diagnostic information used by Holden mechanics during the period these vehicles were produced.
Engine Will Not Start
When an engine fails to start the fault is often found within the ignition circuit or ignition components.
• Battery voltage low or electrical connections loose
• Ignition switch or wiring fault
• Ignition coil defective
• Contact breaker points incorrectly adjusted or burnt
• Condenser faulty
• Distributor rotor damaged or worn
• Distributor cap cracked or terminals corroded
• High tension leads damaged or incorrectly connected
• Spark plugs fouled or incorrectly gapped
Engine Starts But Runs Rough
If the engine starts but runs unevenly or misfires, the ignition system should be checked for component wear or incorrect adjustment.
• Contact breaker points worn or incorrectly set
• Condenser failing or internally shorted
• Distributor cap or rotor worn
• Spark plugs worn, fouled or incorrectly gapped
• High tension leads deteriorated or loose
• Ignition timing incorrectly set
Engine Misses Under Load
Misfiring during acceleration or when the engine is under load can often be traced to weak ignition spark or poor ignition timing.
• Spark plugs worn or fouled
• High tension leads breaking down under load
• Ignition coil weak or failing
• Contact breaker points worn or incorrectly adjusted
• Ignition timing incorrectly set
Poor Engine Performance
A noticeable reduction in engine performance can sometimes be caused by ignition system faults rather than fuel or mechanical problems.
• Ignition timing incorrect
• Vacuum advance unit not operating correctly
• Distributor advance mechanism sticking
• Spark plugs incorrectly specified or worn
• Weak ignition coil output
Excessive Fuel Consumption
Incorrect ignition timing or poor spark quality can increase fuel consumption and reduce engine efficiency.
• Ignition timing retarded
• Contact breaker points incorrectly adjusted
• Spark plugs worn or incorrectly gapped
• Distributor advance mechanism not operating correctly
Backfiring or Detonation
Backfiring or detonation can occur if ignition timing is incorrect or if the spark occurs at the wrong point in the combustion cycle.
• Ignition timing too advanced
• Vacuum advance malfunction
• Distributor advance mechanism sticking
• Incorrect spark plug heat range
Recognising these symptoms can often lead to a quick diagnosis of ignition faults without major dismantling. Because ignition problems can sometimes appear similar to fuel system or mechanical issues, correct specifications and adjustment procedures are important when diagnosing faults.
HK HT HG Holden Workshop Manuals
While this guide helps identify common ignition system problems, the Holden workshop manuals available from Car Manuals Direct include the original specifications, adjustment settings and repair procedures used by Holden mechanics when these vehicles were new.