1961 Mercury 6 cyl DR800 what spark plugs

mrmotor

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I have 2, 1961 Mercury DR800's and trying to find out what are the correct spark plugs for these motors...The shop manual says J4C for block 833-1919 OR J2J for block 833-1688

Q1..how do I tell what blocks I have?? Q2...most mechanics tell me to use NGK B7S or B9S...instead of Champions

The old plugs look really fouled...like they were too cold...I need someone who has old Merc engines to set me straight..
Thanks

MrMotor, Ontario,Canada
 

Laddies

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Re: 1961 Mercury 6 cyl DR800 what spark plugs

J4C are the best all round plug for those engines. If you want to check the block number it's cast in the side the engine that the J@J was recommended for ran a little more compression and we used to put the J2J in if the ran alot of WOT or skied alot
 
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