Re: 60's Sportwin 10 hp VS. 80's Yachtwin 8 hp. Which should I buy?
I have both of those engines. I have a '87 8hp longshaft Yachtwin and a few 10's.
The 10's are easy and cheap to work on. I believe they are all 24:1 as they went to the 9.5 in 64 did they not (or was it '65 - I'm in Florida and dont have my books).
The 8 (and 9.9's) have an inherent problem in the cooling system. The upper cooling tube grommet under the engine collapses and you need to remove the powerhead to fix it. (which is a lot harder to do on the 8's than the 10's) I dont like that. Mine has a cooling restriction now and I'm assuming that's it. And the ignition system is much more complicated... when it last ran well it was a great engine though.
The bottom line is condition. And most importantly, compression. Then price. Rarely are the 2 the same price as they newer 8's had a much higher resale, so if it's cheap or similar to the price of the 10, be wary.