More HP for my 20

[Birdup]

I have heard that the same block is used for many different horspower rating and the only difference is the carb. <br /><br />Does anyone know what hp series was used with the block on my 1969 20hp model# 20R69B (on the transome mount and J3102662 is stamped on the block)?<br /><br />Idealy I would like to upgrade to a 35hp carb. I was told that my block was for 20-35hp. Is this true or was the guy full of it?<br /><br />Thanks

 

[Chinewalker]

Re: More HP for my 20

Hi Birdup,<br /> The guy was at least partially full of it. Your 20hp came in three incarnations - 18, 20 and 25hp. Your motor block is the old 22-cubic inch block - one of the best ever. Upgrading the 20 to a 25 would require (at least) the 25hp carb and intake manifold. I don't recall if there was any porting differences between the 20 and 25hp blocks.<br /> Before throwing a lot of time and money into getting the 25hp parts, you might want to make sure you're getting all 20 of the rated ponies you presently own. How's compression? How is the nearly 35-year old throttle linkage holding up? What condition is the propeller in? Is it the right propeller for the boat and load? A little homework and testing might give you a bit more bang out of your present motor...<br /> The later 33-cube blocks came in 20-35hp incarnations, which is what I suspect your "guy" is thinking of...<br />- Scott