clinton J-9 cooling system and RPMS

[boltbreaker]

Hello to all.<br />I recently acquired an old,neglected Clinton J-9. After a short carb cleaning I had the pleasure of hearing this motor run. It sounds absoulelty BEAUTIFUL. I've owned around 4-5 of the J-9's and this one is MUCH quieter than all of the others.<br />My question is in regards to the cooling system. I know the powerhead is air cooled and the exhuast gases and housing is water cooled. <br />Is it necassarry to run an impeller in one of these? I had one in my teenage years that I put countless hours and river trips on with no impeller and it didn't blow up. I'm not sure if it's "good" for them or harms anything if I dont' replace the impeller in the "nice" one I have.<br />Second question is about the RPM's. They are supposed to put out 5 HP at 6800 rpms. Every Clinton I have owned sounds like it is running WAY less than this. My tach is currently being repaired so I can't give an exact number, but would guess it somewhere at 3000-4000. Anyone have any tips on opening this little devils up? It seems like the water just "bogs" them down to much to put out this many RPMS. I can see ya getting this out of the water but NO WAY under load.

 

[WillyBWright]

Re: clinton J-9 cooling system and RPMS

Regarding the RPMs, Merc used that RPM vs Hp to their advantage in years past. Specifically on the Hurricane, it was advertised as an 11Hp. At 4800 RPMs, that's about what it put out. They chose that number because that's what the Johnnyrudes were running at the time. But the Hurricanes can easily and comfortably run at 6000 RPMs and produce closer to 18Hp. Cheaters! <br /><br />But I agree, the Clintons never come close to that. So I guess you could apply Merc's tactics in reverse.<br /><br />Regarding the water pump, you won't damage the powerhead if it's not there. That was the beauty of those. Hot exhaust will discolor the paint on the leg, but I don't see any other significant consequences.<br /><br />Here's a good source of information, and I know of one guy that got an impeller there...<br /> http://www.discount-marine-parts.com/