Need info on 9.8hp Merc

[Goose Hunter]

I was given a 9.8hp Mercury. It says 110 on the front of the top cover. It's serial number is 3927359. Under the hood it says Thunderbolt Ignition. Can anyone tell me what year this engine is? Also the spark plugs are strange looking. They say 'AC V40FFM Marine' on them. There is nothing to set a gap to, because there is only a center electrode and no electrode on top of center. <br /><br />Also what would the oil to gas mixture be? 50 to 1?<br /><br />What type oil do I use in the lower unit?<br /><br />Hope someone can answer these questions. Thanks in advance.

 

[rickdb1boat]

Re: Need info on 9.8hp Merc

That's a 1974 Model ya got there. Spark plug should be a surface gap champion L78V. 50:1 mix is correct. High Viscosity lube in lower unit. Nothing special that you can't get at walmart.

 

[Goose Hunter]

Re: Need info on 9.8hp Merc

Thanks Rick. Appreciate the quick response.<br />Joe-

 

[BubbaBaxter]

Re: Need info on 9.8hp Merc

As a follow up to your plug question. Though mercs generally use surface gap plugs, if you use your moto primarily as a trolling motor, ask your dealer to check the service manual. It will give you the correct adjustible gapped plugs. Surface gaps are a cold plug and will foul easily with extended slow speed operation.