tired of guessing, i want to know.... 1964 18hp

montff77

Cadet
Joined
Aug 17, 2011
Messages
11
Hi all. What is the difference (what can I change) in the 64 18hp and the 1966 20hp? I checked part numbers and all looked the same besides the reed stops????? Confirm? Deny? Is like to make the conversing bc I don't like leaving ponies on the table ;) that 2hp gains is 11%!!!!!! Who wouldn't want it!!!!! Also, should I mill the head .060 and run 89octane, square the intake ports, blend the transfer area to flow better? I don't want to do iffy stuff to it. Any and all info is Greatly appreciate. Thank you. Great site!!!!!
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: tired of guessing, i want to know.... 1964 18hp

If you are going to do all that work for a possiable 2hp gain, why dont you just get a 20hp engine and forget all the work? You are not going to be able to feel any difference between the two when they are on your boat.
 

kfa4303

Banned
Joined
Sep 17, 2010
Messages
6,094
Re: tired of guessing, i want to know.... 1964 18hp

I agree with Daviet. The 2 hp is negligible, especially for all of that work.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: tired of guessing, i want to know.... 1964 18hp

If it's running good leave it alone. Not worth the $$$$ to mess with it.
 

motoman

Seaman
Joined
Jul 5, 2011
Messages
56
Re: tired of guessing, i want to know.... 1964 18hp

The 60's model 18's are some the best motors made . I would worry about the 2 hp . Sweet running engines.
 

montff77

Cadet
Joined
Aug 17, 2011
Messages
11
Re: tired of guessing, i want to know.... 1964 18hp

Thanks for the replies guys. It would be piece of mind knowing that itd be original
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: tired of guessing, i want to know.... 1964 18hp

Unless you're running it on a small hydroplane where small changes can make a noticeable difference, you really won't notice any bump between the 18 and 20. As you noted, they're virtually the same motor with the exception of the reed stops, which are opened up a tad more on the Johnson 20.
 

montff77

Cadet
Joined
Aug 17, 2011
Messages
11
Re: tired of guessing, i want to know.... 1964 18hp

Thanks. I guess partly I just wanted to know if my assumption was correct. It's nice having that confirmed. I still say that if I see the stops on eBay that I will throw them in and call it a 20.... Some may say why?, but I get stuck on why not????? Better to gain two than loose two even if you couldn't tell.... Wait that'd be four!!!! Lol thanks again.
 
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