1963-1973 Mercruiser all Engines and Drives Service Manual Books 1 and 2, Page 232Get this manual

1963-1973 Mercruiser all Engines and Drives Service Manual Books 1 and 2, Page 232

SPARK PLUGS INSPECT ION 1In pect each plug indi idua ll every 100 hours fo badly worn electrodes, glazed, brok or bliste
to prope spark plugProper pos iti oning of spark plug wi res in up ports is im portant to pr vent ross-firin gSPARK PLUG
INTERCHANGEABILITY NOTE: Impro per ins tallation one of the greal et ingle auses of unsatisfactor spark plug performance
5Always use new gas ket and wipe sea ts in he ad cleanGas ket must be full compressed on lean se als to omple te heat tra
nsfer nd provid gas AC re istor-lype park plugs CR441 or CR431 are used on late pr ductioll MerCruiscr 120-l40-160-200 En
gines They ar' inter hangeab le with C44or C43lipark plugsAs servi ce it m, CR44N or C.R43!' !llugs canused on previo usly
produced "rCrujser lO 120-1 40(6-Cyl-160-_00Tape red at park plug arc Ol :n iJangeable wilh nonlapered (with gasket) spark
Refe topecificalion s" Sectio for reco mme ndations SPARK PLUG DIAGNOSIS PLUG CONDITIONS ACTORS CA US ING THIS CON DITION
COR RECTIVE ACTION Plug "Flash Ove(fi ring from upper terminal to base of plug) Dirty insulator tops oi rt and moi ture on