Confirmation of Spark Plug Sizes

[cmalinowski]

I've got two motors that I'm trying to confirm which spark plug they each take and what the gap of each of them should be. I've tried looking them up on line and seem to be finding conflicting information.

Motor #01 - 1999 Force (by Mercury) 40 HP; Model H040412U; SN – OE317966

Motor #02 - 1993 Mercury 9.9 HP; Model 12048930; S/N #0D21C484

Any help would be much appriciated. I know I had this written down somewhere and I have lost my little notepad with all my notes in it.

 

[galamb]

Your Force is actually a 1998 model and it uses a Champion L76V or QL76V (same plug with the resistor to stop ignition noise on your electronics) - both are surface gap plugs (gapless - so no little thingy on them to gap).

I have no listing for an alternate "gapped" plug and likewise, the NGK BUHW-2's used on (regular) Mercs should not be cross reffed for this model. This particular model uses Merc's CDM ignition which is somewhat different from what you would see on a (real) 40 or 50 horse Merc which uses Merc's Thunderbolt 4 ignition system.

The 9.9 uses NGK BP8HN-10's gapped at .040" - don't cross ref to a Champion plug, if you can't get NGK's go with Autolites (whatever the cross ref)