9.8 Merc vs 7.5 Merc

[KIGuy52]

I have a '69 Merc 110 (9.8 hp) in running condition. I was given a similar era 7.5 hp to use for parts. With the exception of the props, the motors appear to be nearly identical. How does the 9.8 develop more horsepower? I know the displacement, compression, etc. are the same. Is it done by using a larger reed block, carb, etc?<br />If so, how difficult is it to bump a 150 Max up to a 200 hp or so, since I believe they have the same powerhead?<br />Thanks. I'm trying to learn more about this Mercury stuff.<br />JD

 

[Laddies]

Re: 9.8 Merc vs 7.5 Merc

Mostly through port timing and compression

 

[G DANE]

Re: 9.8 Merc vs 7.5 Merc

Blocks are ported different and carbs are different. The 7,5 has casted in "comet" on side of cylinders, the 9,8 "lightening"

 

[achris]

Re: 9.8 Merc vs 7.5 Merc

Originally posted by G DANE:<br /> The 7,5 has casted in "comet" on side of cylinders, the 9,8 "lightening"

Well, you learn something new every day. That's something I didn't know. Thanks.

 

[Chinewalker]

Re: 9.8 Merc vs 7.5 Merc

Actually - all of the 11-cube blocks have the "COMET" casting, but the model 110, 9.8hp models have an additional sticker that says "LIGHTNING" on it to differentiate them...<br /><br />- Scott

 

[KIGuy52]

Re: 9.8 Merc vs 7.5 Merc

Both of mine have Lightning casted into them. The 7.5 has a Comet sticker.