Plug Gap for old 7.5HP Merc?

[AkumalDave]

I TRIED to track this info down on Mercury's site (and others), but was unsuccessful.<br /><br />Trying to get my early 70's K-Merc 7.5HP started for the season. I just got new plugs but realized that I don't have the gap info. The existing ones seemed to be gapped at .34 - but it didn't start with those anyway.<br /><br />Thanks in advance for any info you can provide!<br />Dave<br /><br />P.S. S/n: 3279060 Blue Thunderbolt ignition

 

[corm]

Re: Plug Gap for old 7.5HP Merc?

Hi Dave,<br />The factory plug was a surface gap plug.<br />However the motor idles an trolles much better with Champion L77J4C gaped at 0.040.<br />Good fishing.<br /><br />corm

 

[AkumalDave]

Re: Plug Gap for old 7.5HP Merc?

Thanks corm!<br /><br />FWIW, the existing plugs were Champion L86c...<br /><br />Guess I'll make another trip to the store!<br /><br />regards,<br />Dave

 

[corm]

Re: Plug Gap for old 7.5HP Merc?

Hi Dave,<br />The L86C is about 4 heat ranges hotter than<br />the L77J4C the gap would be the same. I feel that they are to hot of plug unless the motor is used for trolling only. Check the bleed hose,a 1/8 OD hose comming from the bottom of powerhead going to the top for crackes. On the starboard side. the motor is old enough that they maybe rotton.<br /><br />corm

 

[fone_man]

Re: Plug Gap for old 7.5HP Merc?

http://www.ngksparkplugs.com/apps/watercraft/