CHECK SPARKS

Unique Cars - - WORKSHOP BASICS -

SPARK PLUGS If the fuel sys­tem is okay, the next sus­pect is the ig­ni­tion sys­tem. Take out the spark plugs. Let them dry if they’re wet with fuel. Clean them with a brass wire brush and set the gaps (usu­ally 0.6mm)

SPARK AT PLUGS? Re­place the HT lead. At­tach one of the spark plug leads to a spare plug and rest it on the cylin­der­head. Crank again. If there’s no spark, the ro­tor arm or its con­tact in the cap are de­fec­tive.

DIS­TRIB­U­TOR Turn the en­gine so the points are closed. Flick them open re­peat­edly with the ig­ni­tion on. If they don’t spark, hold them open and check they’re get­ting power. If they are, try an­other con­denser.

LOW TEN­SION PROB­LEMS The most com­mon prob­lem is ox­i­da­tion of the con­tact sur­faces of the points, which pre­vents cur­rent flow­ing through the coil. Flick­ing the points or a rub with fine wet-and-dry paper should fix this.

SPARK AT COIL? Re­place the dis­trib­u­tor cap and re­move the cen­tral HT lead. Hold it in in­su­lated pli­ers about 5mm from the cylin­der­head and crank the en­gine. A strong spark sug­gests the points and coil are fine.

HIGH TEN­SION PROB­LEMS The usual ob­sta­cle to spark­ing at the plugs is dirt on the coil, HT leads and dis­trib­u­tor cap. Clean in­side-and-out with petroldamp­ened rags. Re­place any pro­tec­tive rubber caps that have split.

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