Re: 1982 Johnson 35 Tiller Conversion and other questions
Got the tiller conversion completed, and it works good. I'm still wondering about the intake manifold, though. Let me explain the problem.<br /><br />I have the motor mounted on a 1542 flat bottom aluminum boat (max hp rating 35 hp). I don't know the exact weight of the boat, but I would estimate the boat and motor combined (with a small amount of gear) weighs 500 pounds.<br /><br />Compression is good (135 and 133), new fuel pump, new spark plugs, and the spark will jump a 1/2" gap with a strong, blue arc. I completely disassembled the carbs and did a thorough carb cleaning (removed core plugs, soaked, blew out all passages, installed carb kit, replaced all fuel lines). I did a link & synch and set the wot timing at 30 degrees.<br /><br />The antiventilation plate is mounted 1/2" above the bottom of the boat. I am currently running a 10 1/8 x 13 Michigan Wheel Vortex Aluminum prop, but am only getting 4740 RPM's at WOT (via tinytach) and 26.5 mph. Service manual says operating range of 5200 - 5800.<br /><br />This is with only me in the boat at 185#. I have tinkered with different trim angles, but this is the best I can get out of it.<br /><br />I can't imagine that the prop pitch is too great for this boat. It seems to me like it should turn the 13 pitch prop easily. I know this is not the best prop, and I do intend to replace it soon (any suggestions...I don't have a prop shop nearby that will let my try different props out).<br /><br />My only thought is that the intake manifold is too small. The part number on my intake manifold is 390655. I can't find this part number in any reference materials, but all of the pictures I see of the intake manifold show the hole to be the same size (or very close) to the size of the carb throat. The diameter of the hole in my intake manifold is probably half of the diameter of the carb throat.<br /><br />I have considered cutting the hole out to the size of the carb throat, but wanted to ask the experts here first.<br /><br />If you don't think the intake manifold is the problem, any other suggestions?<br /><br />I greatly appreciate your time.