60 HP carbs on a 40 HP Merc

[rsavant]

Has anyone ever done this? I've been hearing of several people doing this, but I have not been able to speak to someone about the cost vs. outcome or difference in performance. I have an '03 Merc 40 (2-stroke, 3-cylinder) that I was considering doing this to. I'd mainly like to know if you also have to change the exhaust tuner. Any info would be greatly appreciated. I'm new to posting on hear, but not new to reading. Lot's of good stuff and apparently good people as well...Thanks ;-)

 

[moderator1]

Re: 60 HP carbs on a 40 HP Merc

Moving to Mercury.

 

[hondon]

Re: 60 HP carbs on a 40 HP Merc

Wo'nt work ,They achieve this HP differential by piston porting and carb jetting.Are you ready to replace those pistons and do the rest of the research you'll need to do.

 

[Chinewalker]

Re: 60 HP carbs on a 40 HP Merc

Hondon's right. What goes in must come out. Simply adding a bigger carb won't do a thing unless the rest of the motor is set up to handle the bigger fuel supply. The carb, porting and exhaust tuner all work together - adding to only one of them will likely make it run poorly.<br />- Scott

 

[rcb175]

Re: 60 HP carbs on a 40 HP Merc

On a related note, I've recently purshased a 40HP 2 Stroke Classic (2000) so I can salvage the Crank fo my 50HP 1998 Classic. While cross checking serial numbers and parts lists, these two motors use the same Powerhead, Crank, Pistons, Rod assemblies etc. The difference must lie with Timing and Carburation. I haven't checked the compatability of these components, but the Power Heads themselves are the same unit. (same bore / stroke / porting etc.)

 

[fast40merc]

Re: 60 HP carbs on a 40 HP Merc

i have a 2002 40 hp mercury just finished putting the 60 hp carbs on it tuner will not have to be touched all u have to do is order u 3 60 hp carburators and 3 reed retainers and all gaskets needed remove 40 hp carbs and reed induction plate remove reed stops and replace with reed retainers put everything back together and your ready to go check spark plugs to make sure your jetting is right i have #70 jets in mine thats what the 60hp carbs come with if u need any advice let me know

 

[Cajuntroutslayer]

Re: 60 HP carbs on a 40 HP Merc

Wow. Just came across this old thread... For the guys that say "this won't work", I beg to differ. We have a lot of marshes in South Louisiana with 40 HP restrictions, and it has become quite common to do this, exactly the way fast40merc describes it. There is even a local machine shop that will do a custom intake plate that's polished, etc that can get you a few more HP. One of the local mercury service dealers here has dyno'd some of the 40's they've built. He has several dyno charts posted on the wall from 3-cyl 40's that are turning 67 HP.

As far as "Is it worth it"?? I have a 16x52 Alweld semi-V. With the stock carbs it ran 33-34 mph. With the 60 carbs and reed stops removed it runs 39-41. The drawback is the fuel economy. It's a very noticeable decrease to push that skiff an additional 8 mph. There are people around here with smaller, flat bottom boats and custom props with these same simple modifications that are running in the mid 50's.

A set of (3) new 60 HP carbs is quite pricy. I came across some on ebay several years back - A guy had torn the lower unit off his 60, and was parting out the top end. I got the carbs delivered to my door for about $150. Yes, it was worth it to me. Do keep in mind you'll probably need to buy a new prop. I had to go from a 14 pitch to a 15 pitch.

Hope this helps anybody considering this...