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1987 6hp Merc, carburetor interchange

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waccamaw

New member
OK, I've had this ole merc for a while and it needs a new carburetor. The 6hp carb is impossible to find, however the 8hp carb (both wmc 19A) is easy to find. From what I can find, they both share the same gasket kit, so I'm figuring they are interchangeable. Am I right?
 
I believe the only difference is the main jet size as long as the number is the same the venturi should be the same. It could be thats the only difference between the HP the 6hp is possibly just a detuned 8hp. If it has the same powerhead just stick the carb on and see how she runs. The only difference I see in my book is the WOT rpms
6hp is 4000-5000 8hp is 4500-5500. If it revs too high just get a prop with more pitch
 
kimcrwbr1 said:
I believe the only difference is the main jet size as long as the number is the same the venturi should be the same. It could be thats the only difference between the HP the 6hp is possibly just a detuned 8hp. If it has the same powerhead just stick the carb on and see how she runs. The only difference I see in my book is the WOT rpms
6hp is 4000-5000 8hp is 4500-5500. If it revs too high just get a prop with more pitch
Click to expand...

Great. Thats what i figured. Guess I will purchase the 8hp carb.
 
The 8 horse carb will effectively turn your 6 horse into an 8 horse.

They also share the same exhaust plate (same size exit hole) with no exhaust tube, so the motor is "capable" of "breathing out" as an 8 horse without modification. The addition of the 8 horse carb, assuming you do not swap out the jets, will allow it to "breath in" as an 8 horse.

This is a "typical" upgrade for this model.

The "rest" of the motor/assembly can handle the two extra horses produced "without issue" and your prop should be fine - they pretty much all came from factory with a 9 pitch prop which was installed on the 6, 8, 9.9 and 15 horse models.

Now if you are starting to think why not just bolt on a 9.9 carb (there are tons of them out there), you "would" need to change the exhaust plate (a little different and has a tube), but it's no longer available. A post 1994 plate is available but also then requires a new water tube and a slight modification to the (leg) exhaust housing - but it can be done. So yes, it is possible to turn a 6 into a 9.9, but it's more $$$ and more work for minimal gain - moving up to an 8 will give it a little more kick :)
 
galamb said:
The 8 horse carb will effectively turn your 6 horse into an 8 horse.

They also share the same exhaust plate (same size exit hole) with no exhaust tube, so the motor is "capable" of "breathing out" as an 8 horse without modification. The addition of the 8 horse carb, assuming you do not swap out the jets, will allow it to "breath in" as an 8 horse.

This is a "typical" upgrade for this model.

The "rest" of the motor/assembly can handle the two extra horses produced "without issue" and your prop should be fine - they pretty much all came from factory with a 9 pitch prop which was installed on the 6, 8, 9.9 and 15 horse models.

Now if you are starting to think why not just bolt on a 9.9 carb (there are tons of them out there), you "would" need to change the exhaust plate (a little different and has a tube), but it's no longer available. A post 1994 plate is available but also then requires a new water tube and a slight modification to the (leg) exhaust housing - but it can be done. So yes, it is possible to turn a 6 into a 9.9, but it's more $$$ and more work for minimal gain - moving up to an 8 will give it a little more kick :)
Click to expand...

Well that is really good news. I really appreciate the help!
 
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