4 barrel vs 2 barrel carburator

[Degree of Freedom]

my 24' Sundancer has a 350 mercruiser with a 2 barrel carb...seems to me for my application a 4 bbl would be more efficient.
I'm pretty ignorant on this topic, hopefully someone who knows more could give me some feedback.
Thanks!
Dan

 

[scott craven]

The 4 barrel would probably give you better performance, but the engine would suck more gas...

 

[Lipripper]

4bbl will give you more hole shot but you can run them off 2 barrels. You can usually hear when the secondary's kick in, just throttle back a bit.

 

[Kristo]

Often the main jets on a 4 bbl may be smaller than a 2bbl but when you floor it the secondary jets open up and you should get more horsepower and increased fuel flow.
Changing manifolds, carb, linkage, etc etc can be expensive and getting the engine to run correctly can be challenging.

 

[Last Chance]

I did on an old 25 foot Bayliner. Chances are you don't have the cam to take advantage of the 4 BBL...

 

[Degree of Freedom]

thanks guys...after doing a little more research, it doesn't seem like a very viable option. Maybe it'll blow up and my insurance will give me an MPI replacement

 

[Doug]

I agree with Kristo.

 

[salmonkiller01]

Often the main jets on a 4 bbl may be smaller than a 2bbl but when you floor it the secondary jets open up and you should get more horsepower and increased fuel flow.
Changing manifolds, carb, linkage, etc etc can be expensive and getting the engine to run correctly can be challenging.

I agree with kristo, on the fuel consumption, I had a searay with a 302, swapped to four barrell and actually found my fuel economy increased, plus saved about 40 lbs by swapping out the old cast intake for an aluminum one. The edelbrock performer with the edelbrock marine carb is a great set-up. I got mine thru lordco.

 

[wolf]

The 4 barrel would probably give you better performance, but the engine would suck more gas...​

wrong again !!!!! stick to what you know.....

A 4 barrel gives you a great hole shot then you ease the throttle back and then you back on the primaries when you hammer it down and again say in rough or you just want "TOO BOOT IT" you will definatlly hear the secondaries kick in.... if your manifold is a 4 bbl one its very simple to change out and replace, as for the engine if its a marine enigine in it it will be fine as it with have a marine cam on her anyways so a carb change in know way will hurt it (as its carbed for either marine carbs).
Ive been playing with these engines for many years and the best was ALWAYS switching to a 4 bbl less fuel consumed and way better performance.
New marine carb are not too expensive anymore 350 to 400 hun get the 650 cfm eldelbrock.


good luck Wolf

 

[salmonkiller01]

wrong again !!!!! stick to what you know.....

A 4 barrel gives you a great hole shot then you ease the throttle back and then you back on the primaries when you hammer it down and again say in rough or you just want "TOO BOOT IT" you will definatlly hear the secondaries kick in.... if your manifold is a 4 bbl one its very simple to change out and replace, as for the engine if its a marine enigine in it it will be fine as it with have a marine cam on her anyways so a carb change in know way will hurt it (as its carbed for either marine carbs).
Ive been playing with these engines for many years and the best was ALWAYS switching to a 4 bbl less fuel consumed and way better performance.
New marine carb are not too expensive anymore 350 to 400 hun get the 650 cfm eldelbrock.


good luck Wolf

I agree 100%

 

[Degree of Freedom]

wrong again !!!!! stick to what you know.....

A 4 barrel gives you a great hole shot then you ease the throttle back and then you back on the primaries when you hammer it down and again say in rough or you just want "TOO BOOT IT" you will definatlly hear the secondaries kick in.... if your manifold is a 4 bbl one its very simple to change out and replace, as for the engine if its a marine enigine in it it will be fine as it with have a marine cam on her anyways so a carb change in know way will hurt it (as its carbed for either marine carbs).
Ive been playing with these engines for many years and the best was ALWAYS switching to a 4 bbl less fuel consumed and way better performance.
New marine carb are not too expensive anymore 350 to 400 hun get the 650 cfm eldelbrock.


good luck Wolf

That was what I was thinking....smaller primaries = less fuel consumption, but as I said I'm totally ignorant on this stuff. It is a marine engine.

Thanks for the input everyone

 

[scott craven]

I used to have an old Pontiac with a 283 V8 , 2 speed powerslide, stock 2 bbl carb.
pretty much a dog off the line.
Changed out the intake manifold and put on a Holley 400cfm 4bbl.
Pretty drastic change in performance and fuel consumption.
granted, this is an automotive engine, and may have been a little heavy on the gas pedal
but i sure didn't use less fuel ?

 

[profisher]

You will get better fuel economy with a 4 barrel if you stay away from opening the secondaries. So if your daily routine involves long runs at a steady rpm...a 4 barrel will save you money and also give you the power if you need it.

 

[wolf]

AHHHHHHMMMMMM a boat travels on water a car on a road bit of a diffeerence dude!!!!!and totally different applications WERE talking BOATS......

Yes pro you are right I run at 3400 rpm and get great economy if i bump it to any past 3900 i hear the secondaries just like any boat motor dont care if its 2 stroke.inboard,or 4 stroke you crank it up it will love fuel!!!!

 

[scott craven]

AHHHHHHMMMMMM a boat travels on water a car on a road bit of a diffeerence dude!!!!!and totally different applications WERE talking BOATS......

Pardon my ignorance.

 

[Blackmax]

A boat is always going uphill and never coasts like a car for that reason no matter what engine or carb you have it will use X amount of horsepower to do the job. I have a v6 and I win over a v8 because of weight and less fuel consumption at idle and very slow cruising speed. However if I was to put 4 people in the boat the v8 would win because of the extra torque it puts out at a lower r.p.m. Fuel injected motors probobly see a 5-10 % less consumption due to effeciency and less time between tune ups. When I am going to Thrasher I take out all the crap I don't really need on board, I don't bother taking water in the fresh water tank etc. I carry enough fuel to go an extra time across as a safety factor, I have a 4 blade Solas prop that I have played with for a few years to get the right pitch for cruising r.p.m. I have seen a lot of guys cruise at 3000 rpm thinking they are going to get better fuel economy but don't realise that another 500 rpm will put them in a sweet spot for speed that translates to fuel economy. But in the end few of us get out enough times to really be concerned. BTW I would vote 2 barrel.

 

[Degree of Freedom]

so...I started this thread almost a year ago, but never ended up doing anything. I'm definitely going to switch to an Edelbrock marine 4 barrel this spring...so now another question (I'm still ignorant on this stuff).
If the new carb fits my existing manifold, is there any advantage to updating the manifold as well as the carb, or am I just wasting money?
Thanks again!
Dan

 

[GLG]

The 4 barrel carb needs a 4 barrel intake manifold.
If you don't want to change the manifold look for a new carb or get the old one rebuilt. This picture is of a 2 barrel gasket, 4 barrel has 4 holes.

 

[GLG]

I did on an old 25 foot Bayliner. Chances are you don't have the cam to take advantage of the 4 BBL...

What he said ....

 

[Degree of Freedom]

Thanks anyway, but not what I was asking