2 barrel to 4 barrel swap

[burtonrider11]

I asked a similar question to this nearly a decade ago regarding a 4.3l V6 2 barrel and decided at the time it wasn't worth. We currently have a 1997 Starcraft 2010SS with a 5.7l 2 barrel Merc.

Just wondering, has anyone tried a new intake and carb set up for a similar boat/engine package? If so, what were your results? I don't know if I want to do something like this or if I should just hold off and look for higher power on the next boat we buy....Boat runs decent now, but of course, the gear head in me wants juuuuuuuuuust a little more power. I am just ballparking a HP gain of 25-40hp, maybe that is way to optimistic. Thanks for any info that anyone can offer!

 

[alldodge]

IMO you will gain about 10HP with installing a Edelbrock 1409 and performer intake. So about $500 or 50 per HP.

 

[burtonrider11]

IMO you will gain about 10HP with installing a Edelbrock 1409 and performer intake. So about $500 or 50 per HP.

Really? What a bummer if that's the case.....Really won't make a lot of sense to gain 10HP. Thanks for the info.

 

[FreeBeeTony]

Do you have Vortec heads?

 

[achris]

Do you have Vortec heads?

If the engine in the 1997 boat is 1997, then yes, it'll have vortec heads.

HP difference between 2 and 4 barrel on that engine is 15. (from the Merc service manual)... Basically, not worth the effort. You MIGHT see 2mph difference.

Chris......

 

[Volphin]

HP is not the goal. Engine efficiency is. The engine will breathe and perform better with a 4bbl rather than a 2. Changing to an Al intake with a properly tuned 1409 and you will see less engine straining from the hole and a more efficient cruise speed, along with secondaries that will open up that air pump when it is time to outrun the thunderstorms. My .74

 

[burtonrider11]

Thanks everyone, I really appreciate the insight. Not sure if this is something I'll move on with, but it's definitely worth thinking about depending upon what it will cost and what it will take to get it done. My major concern is tuning the carb after it's installed - I have zero experience there. The rest of the install should be fairly straightforward, especially if done in the off season and no rush.

Cruise speed is really the optimal reason for doing this, hole shot being secondary. Of course, I would love more top end, but I also understand that it takes gobs of HP to move much faster than 50mph which is about where we are now.....Thanks again for the insight.

 

[roffey]

When I first got my boat the speedo read 57 mph WOT... then I took my gps out with me, LOL. 52 mph.

 

[burtonrider11]

When I first got my boat the speedo read 57 mph WOT... then I took my gps out with me, LOL. 52 mph.

All my readings are strictly GPS. I always refer to the boat speedo's as Dream Machines Though mine is suprisingly accurate up to about 30mph.

Read enough Craigslist ads and there is always at least one joker claiming his Bayliner does 65+ with the 3.0l Inline 4 lol

 

[Rick Stephens]

My major concern is tuning the carb after it's installed - I have zero experience there.

Not having bought and installed one of those Edelbrocks, I still had the impression that they were a snap - if they don't come with the calibration tuning you order it for your application fairly cheaply. Not a lot of tuning to do. I may be wrong, but that is the impression I got.

Rick

 

[roffey]

Read enough Craigslist ads and there is always at least one joker claiming his Bayliner does 65+ with the 3.0l Inline 4 lol

Have you ever noticed you always meet someone who "had" a boat that was considerably faster than yours. I know 50 will not be the fastest but it is truly smokin across the water. Like you said, most people will tell you the boat they are selling will go way faster than possible.

 

[burtonrider11]

Not having bought and installed one of those Edelbrocks, I still had the impression that they were a snap - if they don't come with the calibration tuning you order it for your application fairly cheaply. Not a lot of tuning to do. I may be wrong, but that is the impression I got.

Rick

I don't know that either If that is the case, where it's truly plug and play, that would be a lot more appealing to me. I just didn't want to invest the time to do everything regarding the install and then have to dink around trying to do the tuning. If I don't have to do the tuning, that makes it more viable.

 

[burtonrider11]

Have you ever noticed you always meet someone who "had" a boat that was considerably faster than yours. I know 50 will not be the fastest but it is truly smokin across the water. Like you said, most people will tell you the boat they are selling will go way faster than possible.

Yup, there's always one When we bought our boat, the previous owner said that the fastest he's gone via GPS was 54 and that was under absolutely ideal conditions. I am going to do some water testing this fall when the kids are back in school and there is less traffic on the water. I'll be interested to see what a 1/4 tank of gas and just me on board will yield....

 

[alldodge]

My major concern is tuning the carb after it's installed - I have zero experience there.

The easiest way is with a vacuum gauge, but most marine intakes don't have a vacuum port. Without that, have the motor all warmed up idling at 650-700 rpm. Turn the mixed screws in slowly until you notice it start to stumble, then reverse 1/4 turn. Repeat this with the other mixer screw. This would be a good place to start and use the boat.