RUN­NING CLEAR­ANCES JAR­GON BUSTER

Mini Magazine - - Mini Tech -

Th­ese are terms that folks get con­fused over, so I’ll make it as clear as pos­si­ble. All di­rec­tions re­ferred to are when view­ing the en­gine from the front, the coolant pump end.

Ad­vanced cam tim­ing means the valve open­ing/clos­ing events are oc­cur­ring ear­lier than the ba­sic cam ge­om­e­try de­scribes as pro­duced by the camshaft man­u­fac­turer. Con­versely, re­tarded cam tim­ing means the valve open­ing/clos­ing events are oc­cur­ring later than the ba­sic cam ge­om­e­try de­scribes as pro­duced by the man­u­fac­turer.

Ad­vanc­ing the cam tim­ing re­quires the cam to be ro­tated clock­wise in its jour­nals. When us­ing an off­set cam key, the off­set part that sticks out of the cam to en­gage the pul­ley should be to the left of the key-way. With dowel type vernier ad­justable cam gears, the dowel needs to be pulled out and re-in­serted into the next hole clock­wise, once the hole be­low has been cor­rectly aligned. With slot­ted/ rota-slide type cam gears, ei­ther ro­tate the in­ner sec­tion that is fixed to the cam clock­wise by us­ing a span­ner/socket on the cam gear re­tain­ing nut, or the outer sec­tion car­ry­ing the chain anti-clock­wise by ro­tat­ing the crank­shaft/pul­ley bolt.

Re­tard­ing the cam tim­ing re­quires the cam to be ro­tated anti-clock­wise in its jour­nals. When us­ing an off­set cam key, the off­set part that sticks out of the cam to en­gage the pul­ley should be to the right of the key-way when viewed from the end of the cam. With dowel type vernier ad­justable cam gears, the dowel needs to be pulled and re-in­serted in the next pair of holes anti-clock­wise, once the hole be­low has been cor­rectly aligned. With slot­ted/ rota-slide type cam gears, ei­ther ro­tate the in­ner sec­tion that is fixed to the cam anti

clock­wise by us­ing a span­ner/socket on the cam gear re­tain­ing nut, or the outer sec­tion car­ry­ing the chain clock­wise by ro­tat­ing the crank­shaft/pul­ley bolt.

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