qd 16 low power

[1955murman]

I recently got a qd-16 johnson 10 hp from my grandfather. It had been sitting for a couple years. I changed the impeler cleaned the points, changed the plugs and ran some new gas through it and it started right up. I took it out in the water for the first time 2 weeks ago and it ran fine but it didn't have much power. I also have a 56 Ad-10 7.5hp that I rebuilt 2 years ago and I've noticed that it has pretty much the same amount of power as my QD-16 10hp. I talked to my grandfather and he said that it was always a bit of a bogger.
Is this typical of that engine or is there something I should look for. it runs good. lots of spark just pretty gutless.
Thanks

 

[bowman316]

Re: qd 16 low power

maybe it is the prop, maybe it doesn't have enough power to push that diamater of prop. A lower pitch would help you get on plane quicker

 

[coolguy147]

Re: qd 16 low power

hows compression? and did u rebuold the carbs with a new float? cleasn them too.


also i might add did u properly adjust ur needles?

 

[wbeaton]

Re: qd 16 low power

Those QD's are not normally dogs. It should have a lot more power than your AD. On my 12' boat a strong running AD will get me up to 22 kph / 13.7 mph whereas a 1949-57 QD will push at 32 kph / 20 mph.

If you have low compression you will have low power. How did you set the carb after the rebuild?

 

[1955murman]

Re: qd 16 low power

I did a compression test today. i've got about 85psi per cylinder. Is this ok or is that low. I've got an old johnson shop manual but I can't find it in there any where. also does anyone know where I can get a carb rebuild kit for this thing. The johnson dealer I talked to said they couldn't get it.
Thanks for all the replies

 

[samo_ott]

Re: qd 16 low power

85#'s a side is not bad. It should go ok. What kind of boat is it and how much weight do you have in it? And as Wayne asked, how did you set the carb up? Play with the high speed adjustment and see what happens. And you should rebuild the carb to be safe.

 

[F_R]

Re: qd 16 low power

I did a compression test today. i've got about 85psi per cylinder. Is this ok or is that low. I've got an old johnson shop manual but I can't find it in there any where. also does anyone know where I can get a carb rebuild kit for this thing. The johnson dealer I talked to said they couldn't get it.
Thanks for all the replies

The dealer is ill-informed, or
The dealer doesn't want to bother with it, or
The dealer doesn't want to be bothered by you, or
Whatever.

The carburetor kit is part number 439071 from any Johnson or Evinrude dealer. Or 18-7043 right here at iboats. The 439071 costs more, but you get a new ethanol resistant float with it.

 

[F_R]

Re: qd 16 low power

But hold on here!! We have a big unanswered question: What kind of boat is it on? In order to go fast, a boat has to plane. That means skimming along up on top of the water instead of displacing or going through the water. If it is going at displacement speeds, that is limited by the speed that water flows, and it just won't go any faster unless you can get it up on plane.

Some boats are designed to be displacement boats and won't plane no matter how much power you put on the transom. Other boats are designed to plane but require a certain minimum amount of horsepower to get it up on top of the water.

The motor simply may not be capable of planing the boat, and all the propellers and carburetors in the world won't fix it.

 

[coolguy147]

Re: qd 16 low power

cant believe nobody thought about spark.


hows ur spark can u check it for us?

sure u may have cleaned the points but what about the other items coils and condsors they could be bad? did u gap the points to .020 gap?