18 hp ?

[duckbuster38401]

i have a 1961 18 hp johnson fd-15 should this put a 14 ft v bottom on plane? i acts like it does not have a high enoughf rpm? what could be wrong?

 

[Paul Moir]

Re: 18 hp ?

Could be dropping a cylinder, does it sound like half-speed?<br />How heavy is the 14'? What's it's nameplate max HP?

 

[duckbuster38401]

Re: 18 hp ?

yes it sounds like half speed, the max hp is 30..i can p/u the boat by my self it is lite

 

[duckbuster38401]

Re: 18 hp ?

i pulled the plugs the bottom pug looked like it was not burning all the fuel...very wet...i checked both plugs for fire both had good fire..is the motor just to small?

 

[duckbuster38401]

Re: 18 hp ?

how could i tell if it is dropping a cyl?

 

[bubbakat]

Re: 18 hp ?

Jason that depends on the set up. Where is the cavation plate located in relation to the bottom of the boat.<br />As for the rpms you might not have the right size prop in relation to the load your trying to push.<br />If the cavation plate is below the keel it will create drag and labor the motor.<br />If the engine has been sitting awhile it may need a tune up and decarb and a carb rebuild to get the max out of it.<br />Keep posting and we can figure it out.<br />I see you are in columbia, I am in McMinnville.

 

[Paul Moir]

Re: 18 hp ?

I think you just did. The plugs should be identical.<br /><br />I would think that the 18hp should plane your boat off no problem when it's working right.<br /><br />Try this - see how far a gap you can get the spark to jump. Sometimes, no actually quite often an ignition coil will crack and it'll arc over at higher rpms causing a misfire in one cylinder. That cylinder will not be able to jump much of a gap. Try around 3/8"

 

[duckbuster38401]

Re: 18 hp ?

can you exp this to me it is a short shaft cavation plate is below the keel

 

[duckbuster38401]

Re: 18 hp ?

sorry, messed the post up i dont understand what this means (cavation plate is below the keel)

 

[Paul Moir]

Re: 18 hp ?

If I'm not mistaken, the '61 18hp cavitation plate will normally be a fair bit below the keel. Just make sure for now that it's no more than 2 or 3". I guess they did this because their waterpumps must be submerged for idle operation. On my '63 28hp, it measures almost 18" to the plate to fit a 15" transom, putting the plate 3" below the keel.<br /><br />EDIT:<br />Cavitation plate below the keel means how far the flat plate above the propeller is from the bottom of the boat.<br />Here's a picture of a normal setup:<br />

<br /><br />I think you have an engine problem though.

 

[bubbakat]

Re: 18 hp ?

That plate needs to be even with the keel or no more then 1 and 1/2 inch above it.<br /><br />I have a 1957 18 h/p and it plans a 16 foot flat bottom but that is two different types of boats and the 61 ought to plane that v bottom.<br />OOps paul is right I forgot about the water pich up.<br />Listen to paul he is pretty doggone sharp on this stuff.

 

[duckbuster38401]

Re: 18 hp ?

what is the keel? is this the bottom of the boat thats for the pic that expl the cavation plate

 

[Paul Moir]

Re: 18 hp ?

Yup, the middle of the bottom of the boat. Where it is it's deepest.<br /><br />Bubbakat - you've got one of these huh? Am I out to lunch on the leg length thing?

 

[duckbuster38401]

Re: 18 hp ?

paul i can snd you a pic of it..how do i do it on here or do you have an e mail add

 

[bubbakat]

Re: 18 hp ?

Paul I ain't really sure about the plate now I have mine even with the keel ( bottom of the boat)<br />That is the only way I could get it to handle right.<br />Haven't had any probs with water pick up either.<br />I do know that plate has to be right on top of water or below it. In other words it can't plane up as high as the late model motors.

 

[Paul Moir]

Re: 18 hp ?

Bubbakat: I guess it can't be as bad as mine then. A relative just got a 2000 6hp Johnson (yeah, I know), and in the manual it insists the cav plate be at least 1.5" below the bottom of the hull. Or "Serious Powerhead damage could result." <br />Posting a pic here is a bit of a pain. I can sort of put it up if you email the pic to me:<br />Paul.Moir@ns.sympatico.ca

 

[Paul Moir]

Re: 18 hp ?

Looks a little low to me, but that's a shortshaft engine on a shortshaft transom. When you get it working right, it'll probably help to raise the engine up some.<br /><br /> Jason Martin's Outboard, click here.<br /><br />Is that a 2-blade prop on there? I see no V in that hull either...

 

[duckbuster38401]

Re: 18 hp ?

thank you i will move it up...for noe i will try the gap test..it the bottom end is not jumping the 3/8 gap what will i need to do to fix it..thank you

 

[Paul Moir]

Re: 18 hp ?

No big deal. Your gonna need to get a repair manual (but it's a really good thing to have - mabey the local library has one), a new ignition coil or two ($17ea from Iboats, or NAPA autoparts, 18-5181). You'll also have to get or borrow an automotive harmonic balancer puller to pull the flywheel (pretty cheap), some 1/4"-20tpi bolts to go with it (cheap), and a ft/lb reading torque wrench for the flywheel nut (the torque is important on this one).<br /><br />If you move it up, make sure you're still getting the same amount of water out the back as you did before you moved it at idle and at full throttle.

 

[duckbuster38401]

Re: 18 hp ?

ok thank you for the help