Couple of Merc 120 questions

[trm]

Circa '77 merc 120:<br /><br />The boats at the lake (2 hrs away)and all the info is there.<br /><br />Just rebuilt the Rochester 2bbl and noted in message below that the float level adjustments in the manual are different than the NAPA supplied figures (a special list of adjustments for marine applications was enclosed in kit, and followed in rebuild). Does anyone have their manual handy with the correct specs for my rig? Also, NAPA lists 2 spark plugs for this engine and, as the manual is 2hrs away, can you supply me with the correct plug numbers?<br /><br />Thanks for all help,<br /><br />swabbie

 

[trm]

Re: Couple of Merc 120 questions

Thanks for all the help

 

[Walleye King]

Re: Couple of Merc 120 questions

Okay I got my book today! <br /><br />Plugs for your merc are going to depend on the s/n up to 3825578 take an AC-CR44N<br />s/n3825579 take an AC-MR43T.<br /><br />Those are the only 2 listed! Hope this helps.

 

[Walleye King]

Re: Couple of Merc 120 questions

Well "For The Record" I looked at my engine on the valve cover and the plugs to be used are listed as AC R43T and the gap is .035. Now either the book is wrong or they are similar plugs and I can't say!

 

[horndog]

Re: Couple of Merc 120 questions

i have my manual....<br /><br />And I also own a 120hp merc circa 1978 <br /><br />Ignore the napa one and go with the manual ones. I went with the NAPA ones and I ended up squirting gas out of the float overflow vent. Not good...<br /><br />Float level with the upper carb body upside down with the float on the upside should be set to 21/32" with the gasket on<br /><br />Float drop is 1 3/4" with the gasket on<br /><br />spark plugs can be:<br /><br />ac: MR43T<br />Champions: RBL8<br />NGK: YR5<br />NGK platinum: YR5VX<br /><br />I personally use the NGKs<br /><br />spark plug gap is .035" or .89mm