Johnson 3Hp Seahorse

[doug3386]

I have the unit ready for a test on the back of the boat in the pond.<br /><br /> Can anyone tell me what the nominal settings are for the low and high speed jet screws. That is the number of turns out from the seated position? <br /><br /> I used Tom Travis' article to set the timing and found it very helpful. <br /><br /> The carb butterfly linkage arm was fatigued and broken, probably from overtightening the set screw. With a piece of flattened copper pipe I was able to cut and shape a reasonable facsimile that fit up fine.<br /><br /> Are new motor parts available for this model from a source other than OMC? Just asking in case...

 

[Paul Moir]

Re: Johnson 3Hp Seahorse

Ya screw em all the way in until they bottom out (go easy on them). Then back the top (idle mix) one out 1 and 1/2 turns, and the bottom one (full throttle mix) out 3/4 of a turn or so.<br /><br />Start and warm the engine on the boat for a few minutes (fiddle with the idle mix control if you need to), then go to full throttle. Turn the high speed control in slowly until the engine coughs. Then turn it out until you get the highest RPMS then just a bit more. Drop down to idle and do the same for the idle mix, but make 1/8th turns and wait a few seconds for the engine to respond. Once that's set nice, go full throttle again and adjust the high speed again (they affect each other a bit). When your all done, centre the knobs and put them back on.<br /><br /><br />Various 'consumable' parts like impellers, ignition coils, points, head gaskets, and such are also available from aftermarket engine parts supplier Sierra via dealers such as Iboat, NAPA autoparts, and a host of places online. Lots can still be gotten from the dealer too, pretty darn cheap really. Aftermarket parts only seem to have a %10 to %25 edge over factory parts. I always make an exception for the ignition coils which seem beter to me than stock.

 

[TTravis]

Re: Johnson 3Hp Seahorse

Doug,<br /><br />Thanks for the kind words. <br /><br />I don't know where you can buy that linkage new, but the boat salvage yards have plenty of them. I had to take mine off and tap with a hammer my linkage to tighten up the screw holes. This forum is hosted by IBoats.com, so I would suggest trying them first. Siara is a company that makes a lot of after market parts. You can get their catelog and parts at NAPA and CarQuest auto parts.<br /><br />I will update my site to include the folling information from Joe Reeves:<br /><br />(Carburetor Adjustment - Single S/S Adjustable Needle Valve)<br />(J. Reeves)<br /><br />Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.<br /><br />Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.<br /><br />Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.<br /><br />Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.<br /><br />When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.<br /><br />--------------------<br />Joe (30+ Years With OMC)<br /><br />ReevesJ32@aol.com

 

[Archangel2005]

Re: Johnson 3Hp Seahorse

how do you know if you have adjustable needle valves?<br />i have a 115 horse 1977 johnson<br />double carbs