3 cyl Merc 40

[Cajun Special]

Ported, cylinders honed, new pistons etc, flywheel substantially lightened. 60 carbs with .62 jets. Garrett turbo. Just kiddin. Block stuffed. You or anyone know if velocity stacks worth foolin with? Oh 1.83 ratio. Prop is a Ron hill 11.25x16 semi signature. That one and the signature 18p are AWESOME propellers. rocket fans is what I call them

[tyst67]

Ported, cylinders honed, new pistons etc, flywheel substantially lightened. 60 carbs with .62 jets. Garrett turbo. Just kiddin. Block stuffed. You or anyone know if velocity stacks worth foolin with? Oh 1.83 ratio. Prop is a Ron hill 11.25x16 semi signature. That one and the signature 18p are AWESOME propellers. rocket fans is what I call them

That's sweet! Mine is ported polished, timing advanced, 40 single carb, 40 reed cage, reeds cage drilled bigger, leg and foot sharpened razor sharp used with a 18p Merc chopper 2! 58.7 mph on gps! My motor is the same motor as the triples but with one cylinder chopped off! Twin with single carb! I am buying the 60 carbs this winter and putting them on! I would definatly put stacks on and try it, when I remove the cab of my motor I gain a mph or 2! Have you or anyone here heard of the raised pistons you can get for these motors?

[Cajun Special]

I've heard of those pistons but don't know anything about em. I put mercury pistons in mine. 125psi compression in all 3. U know anywhere in the US where they make stacks? Talked to a guy yesterday in austrailia that makes them. They look real good. Don't cost much

[tyst67]

I've heard of those pistons but don't know anything about em. I put mercury pistons in mine. 125psi compression in all 3. U know anywhere in the US where they make stacks? Talked to a guy yesterday in austrailia that makes them. They look real good. Don't cost much

I don't! I'm from up in canada and that stuff is pretty limited up here! Wonder how much gain they give you? Did hydrotec do your motor work?

[HGipson]

The velocity stacks won't help from what I've been told. My motor has everything done to it besides the lightened flywheel. Haven't found a burnt up crank shaft to chop the end off of to chuck up in the lathe. That's a really good speed with that 2 cyl 40 single carb. What kinda boat do you have it on?

[HGipson]

Hydrotec did most of mine. Did all the porting and a new piston on the top cyl because it wanst getting enough oil I'm guessing.

[tyst67]

These boats are awesome and I would love to see your motor on one! They only weigh around 150 pounds! Me and my dad designed them 6 years ago and we have been making big gains ever since! http://www.boatracingfacts.com/forum...od-boat-design

[pdt]

30 hp 640 cc 2 cylinder merc with the 40hp upgrade ????????
what 40hp upgrade ? you saying its now the twin 40hp

what year is this motor ?

what rpms is this engine doing ?

[tyst67]

30 hp 640 cc 2 cylinder merc with the 40hp upgrade ????????
what 40hp upgrade ? you saying its now the twin 40hp

what year is this motor ?

what rpms is this engine doing ?

Yes sir it has been converted to a 40hp but it probably has more power than a 40 now! http://www.mercury-marine.eu/mercury...el=SeaPro%2040 my motor came with a restricted carburetor! All you have to do is change the carb and reed cage and it's a 40!

[pdt]

sounds good little engine.
I think by trying 60 carb youl find it will go slower.
the 60ho has three carbs, so each of those will be far too small.

might be best to look around for a set of 50/60 hp carbs from a twin cylinder and make a twin manifold.
but if this goes like you say I think best to stick with what you got.

what are the rpm's when your running flat out on it now ?

.