JohnnyRude question

[chumbucket]

Skools, Ferm, any other JohnnyRude gurus;
On the 3 cylinder 50/60/70 hp motors, they are all essentially the same. Right? What are the differences that make up the horsepower variables? Is it all carbs? Are the reeds different? I'm almost sure that the bore and stroke are the same on these motors, but could be wrong. I really don't know.
Please enlighten me.

[THEFERMANATOR]

I know that there were some different ignition systems used on them early on(non magneto styles). I'm not really up on the old loopers myself, only the 90 degree engines. But OMC was famous for making only small changes to each engine and keeping the block and such the same across the board. Normally the tuners were different as well as carburation. Some years had different reeds as well. MERCURY was the one that made it complicated, they would make 6 different variations of a block and they would all be the same HP rating. You can always go here http://12.2.215.22/pub/default.asp?S...g=EN&brands=EJ and look up the different part numbers for each engine to see what changed.

[chumbucket]

Thanks Ferm. That catalog looks like it'll take a while to sift through. I was hoping for some quick easy answers. I'll peruse the differences in that catalog late tonight when there are fewer disturbances in the house.

[chumbucket]

I guess what I'm wondering is; how difficult would it be to say, turn a 50 hp 3 cylinder into a 70 hp 3 cylinder. Can I just change the carbs and get the extra hp out of the motor? I'm looking at a bigger motor, but was wondering if I could save myself some dough and do the simple upgrade.

[THEFERMANATOR]

What year is it?

[chumbucket]

1997