Going down to a 2 barrel from a 4 barrel

[Albacore Fever]

I have a V-6 Vortec 4.L engine in my Welcraft coastal 218 and right now I have a Holley 4160 carburetor on it, I am finding that its a real gas hog, my censor says 13 gallons per hour at about 3500 rps and 24 mph. I have been wondering if I could do better if I went to a Holley 2300 carburetor. guess the big question is if it could get me up on plane with the heavy boat. I'd really like to get more range on my boat for fishing offshore. the boat did come with a 4 barrel carburetor.

 

[bruceb58]

Re: Going down to a 2 barrel from a 4 barrel

Going to a 2 barrel isn't going to help you much. Your fuel usage sounds very high. Less than 2MPG. I get 2.6 with the boat in my sig.

Is your boat getting up on plane completely? Do you have bottom growth(I know you are in Redding but had to ask)?

I would focus on making sure your current carb is working properly(do a spark plug read) and that the engine is mechanically sound(compression, in tune).

 

[Albacore Fever]

Re: Going down to a 2 barrel from a 4 barrel

Going to a 2 barrel isn't going to help you much. Your fuel usage sounds very high. Less than 2MPG. I get 2.6 with the boat in my sig.

Is your boat getting up on plane completely? Do you have bottom growth(I know you are in Redding but had to ask)?

I would focus on making sure your current carb is working properly(do a spark plug read) and that the engine is mechanically sound(compression, in tune).

Thanks, yes its getting up on plane fine now, after putting the new Holley carburetor on its doing great, no growth cause I don't leave it on the water for more than a few days at a time. its is a very heavy boat, I took it to the scales and found it to be about 5800 lbs. the engine a new vortec, I have put about 120 hrs. on it.

 

[bruceb58]

Re: Going down to a 2 barrel from a 4 barrel

I took it to the scales and found it to be about 5800 lbs.

Including trailer right?

That is a pretty heavy boat for a 4.3L.

No way I would change to a 2 barrel carb...not a chance.

 

[frantically relaxing]

Re: Going down to a 2 barrel from a 4 barrel

I've seen more than one Holley power valve that leaks or dumps fuel early. I'd pull it out, and get one 1/2" step lower, as in, if it's a 5 (opens at 5" of vacuum or less) I'd change it to a 4.5. I'd also consider changing the jets down. I did exactly these things with this carb--

-before changing it out for an Edlebrock. I changed the 5 p-valve to a 4.5, and changed the primary 72 jets for 68's --note that our boating elevation is 4400 to over 6000'. The boat barely ran before these changes at 6200', afterwards was a world of difference! Lost the black soot I was getting on the transom, it would idle, cruised nicely... Leaky power valve was the main culprit!

And FWIW, since you're contemplating changing carbs, even after the fix I thought I could do better with the Edlebrock. Nope. Not one bit of change, in any category you can think of. Other than ease of tuning, which the 'brock didn't need, it was a complete waste of money... I still have the Holley too

 

[bruceb58]

Re: Going down to a 2 barrel from a 4 barrel

I would be careful changing jets around unless you know you are running rich. Setting up an engine too lean and you are asking for melted pistons.

 

[Albacore Fever]

Re: Going down to a 2 barrel from a 4 barrel

That's the boat, and when you add things like downriggers and people and gear I bet its up around 7 k so guess I better just stay with the 4 barrel and work on getting it tuned and staying out of the secondaries when possible. I do have a carter 4 barrel that may do a better job if I could get someone to set it up for the boat, I had it on the boat but it just didn't get the boat up on plane and work properly, thinking it was just a case of not having it tuned right. just wishing for better fuel economy and range. Don

 

[Albacore Fever]

Re: Going down to a 2 barrel from a 4 barrel

Ok thanks for your advice, great site here, I'm learning a bit at a time.

 

[bruceb58]

Re: Going down to a 2 barrel from a 4 barrel

Take it out and run at your normal cruising speed and then go and shut it down with minimal idle and pull a few plugs. You can tell from that if you are running rich or not.

 

[jimmbo]

Re: Going down to a 2 barrel from a 4 barrel

A Holley 4175 would be better choice for the 4.3. It has small primaries, and large secondaries, like the Qudrajet. If you're going to mess with the jetting beware that on a Holley changing the jets affects both part throttle and WOT calibration. If you want to lean out part throttle but keep the same ratio at WOT the you will need to drill out the orfices in the metering block. If you wanted richen the part throttle but keep WOT it gets more complicated. The current orfices would need to be plugged then redrilled smaller. If you start changing power valves, you need a vaccum gauge and to be able to interpret what it is reading at different rpms. If the opening point is too low the engine will be running lean when it needs the fuel. If the opening point is too high then you are running too rich to soon and the engine will not be as responsive. Plus economy drops. Older Holley carbs when exposed to a backfire in the intake, would often have the Power Valve diaphram rupture. Later models had a check valve in the vaccum supply passage to prevent that, however carbon deposits sometimes rendered it unworkable.

 

[Albacore Fever]

Re: Going down to a 2 barrel from a 4 barrel

I'll check the plugs, not thinking its set rich because it doesn't load up while I have been doing the slow trolling for salmon. beginning to think these Holley 4161 carburetors are great but maybe not so good for fuel savings.

 

[Albacore Fever]

Re: Going down to a 2 barrel from a 4 barrel

I'll do some checking around on that 4175 Holley, wished I would of know this a few weeks ago. this is a brand new carburetor. Don

 

[bruceb58]

Re: Going down to a 2 barrel from a 4 barrel

I'll check the plugs, not thinking its set rich because it doesn't load up while I have been doing the slow trolling for salmon. beginning to think these Holley 4161 carburetors are great but maybe not so good for fuel savings.

When you are idling, the jets really aren't even in play. Its only above idle. That's why you have to do a high speed run before you check your plugs.

 

[jimmbo]

Re: Going down to a 2 barrel from a 4 barrel

Whatever carb you do choose make sure it is a Marine Carb.