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GuitsBoy
07-07-2008, 10:22 AM
How do I identify the carb on my 92 prostar 205? I know it came from the factory with the 4010, but how can I tell if a previous owner replaced it with a 4160 or might have even rebuilt the stocker. The boat has 800+ hours and the motor seems to be running pig rich, drinking fuel quickly, lacks a little top end grunt, and has some bogging out of the hole. The problem is, Im carb-stupid. I know my way around EFI, but this is my first experience with this ancient technology.

Thanks guys!

denverd1
07-07-2008, 10:51 AM
the 4010 has dual fuel lines, one for each bowl. the 4610 has a vacuum secondary that pulls off the front of the carb. There are also a few numbers behind the choke horn (example: R85) on the carb that will help you identify it. I'm not 100% sure what the choke horn numbers mean, but I'm sure someone can clarify that for us. I was thinking stock jet sizes, but not sure on that one...

GuitsBoy
07-07-2008, 10:53 AM
OK, my carb has a chrome fuel rail with two outlets, front and rear, I assume this means its a 4010. I guess thats the fuel line that needs to be replaced when moving towards the 4160? Thanks!

rholmes
07-07-2008, 10:54 AM
If it is a 4010, it will have a fuel line running to both the front and back bowl. The 4160 has one fuel line entering from the front. From there, one small tube runs from the front bowl to the back bowl. If you are looking at the carb from the front where the belts on the engine are, it will be on the right side. Attached is a pic of the 4160. The line connecting the front and back bowl is not attached, but I held it up in place so you can see where it is located.

http://i98.photobucket.com/albums/l256/rholmes69/1990%20Maristar/100_2993.jpg

GuitsBoy
07-07-2008, 11:13 AM
If it is a 4010, it will have a fuel line running to both the front and back bowl. The 4160 has one fuel line entering from the front. From there, one small tube runs from the front bowl to the back bowl. If you are looking at the carb from the front where the belts on the engine are, it will be on the right side. Attached is a pic of the 4160. The line connecting the front and back bowl is not attached, but I held it up in place so you can see where it is located.


Custom pictures of the carb just for me? Im not worthy! You guys are the best. Thanks.

So with 800 hours and the slight bogging issue, do you guys think I should try a rebuild or more likely just replace with the 4160? The boat is sucking down well over 5 to 6 GPH wakeboarding with 1600 lbs ballast. It is the 351 HO / 285 for what its worth, maybe the fuel consumption is not all that outrageous.

Thanks again

rholmes
07-07-2008, 11:27 AM
Fuel consumption actually sounds really good. I think the best I have seen people report unloaded is around 3-4 gph. If you are not afraid to try it (and it is really quite easy, just seems daunting), I would pick up a used 4160 and rebuild it. The rebuild kits are available from autozone (the marine versions) for under $30. Usually takes them 1-2 days free shipping to get to your store. That seems to be one of the top 5 upgrades people do is to switch for the less problematic 4160. It is more reliable and less prone to two issues, heat soak and the front bowl emptying into the venturies (I think I spelled that right?) when getting on plane. A lot of people tend to think the acceleration is better on the 4160.

You can pick up a used carb that needs a rebuild for around $50 all day long from craigslist, ebay, etc. Here is one on ebay: http://cgi.ebay.com/ebaymotors/HOLLEY-4BBL-CARBURETOR-4160-600CFM_W0QQcmdZViewItemQQcategoryZ133205QQihZ011QQ itemZ320270156576QQrdZ1QQsspagenameZWDVW

IMHO, I would get a used 4160 for under $75, rebuild it and have a new carb that is less prone to problems for under $100. Then just rebuild the 4010 and keep as a backup in case anything happens. If you don't like the performance, you have a rebuilt 4160 that you could easily get back your money for if not actually double it.

GuitsBoy
07-07-2008, 11:41 AM
Thats a great idea. I dont mind doing the rebuild at all, Im sure im capable of doing so. My problem is that I dont know how to tune these things.

In the automotive world, Im no stranger to building motors, juice, forced induction setups and even even porting my own heads, but Im used to adjusting fuel graphs on a laptop. This old school stuff is completely foreign to me, and unfortunately I dont really have a mentor readily accessible to show me the ropes. Iv always assumed tuning a carb was a bit of a black art and not a hard science that you could explain on paper.

Anyway, how do I know if its a marine carb or not? or are all 4160's marine? I dont know the difference between applications. I know its the 600 cfm to look for, right?

Thanks again for bearing with my lack of knowledge...

rholmes
07-07-2008, 12:23 PM
The 4160 is very simple to tune. It has a two screws, air on the left side and fuel on the right side. I think i have some "helpful Hints and tips" files for tuning. IIRC, the factory adjustments are 1.5 turns out for air and 3/4 turn out for fuel. Then you just go from there. Basic dialing in is done out of water with a hose hooked up, finally tuning in the water. It reacts pretty quick to your adjustments. I can send you the files or get you the links to them if you want. It isn't a black art at all. I knew squat when I started and just have what I downloaded offline and what it was set at before I started the rebuild. Plenty of info out there to help you out.

A marine version of the carb isn't necessary, you just need the marine rebuild kit. It is 703-47. And yes on the 600cfm. IIRC, the main difference between a marine carb and street carb is the J-vents. A street carb vents into the engine area and and the marine carb vents back into the carb (See the j-vents in the picture). Most people end up cutting the j-vents off to reduce air flow blockage (not a big deal on our boats).

denverd1
07-07-2008, 12:26 PM
No, not all 4160's are marine. The ebay one is NOT marine either. Rholmes' is marine, with fuel return tubes that dump back into the carb. There are a few other changes, like the rubber cap right above the secondary vacuum line.

Guitsboy, the fuel rail for the 4010 will breakdown to a single fuel line. The 4160 should match up with the fuel line before it T's. Fittings are the same.

GuitsBoy
07-07-2008, 12:35 PM
I would think that the carb has parts (specifically those fuel returns) that are not necessarily part of the marine rebuild kit, no? I dont think I want to chance converting a street carb to a marine carb.

So Ill look around for a marine 4160 - 600 CFM. The application shouldn't matter as Ill be adjusting the screws to stock specs after the rebuild anyway, correct?

Thanks again guys. My google-fu was not turning up much specific info.

TMCNo1
07-07-2008, 12:51 PM
No, not all 4160's are marine. The ebay one is NOT marine either. Rholmes' is marine, with fuel return tubes that dump back into the carb. There are a few other changes, like the rubber cap right above the secondary vacuum line.

Guitsboy, the fuel rail for the 4010 will breakdown to a single fuel line. The 4160 should match up with the fuel line before it T's. Fittings are the same.

The convert to a 4160 from a 4010 will require a new entire fuel line from the fuel pump to the carb. The 4010 comes in on the starboard side and splits and the 4160 comes in on the port front side. Finding a solid steel Indmar line will be nearly impossible to find since they have quit making and selling them and Skidim only has the PCM line which is about 1/4" too short due to the different fitting setup they used, so a custom fabbed stainless braided fuel line is just about your only choice. A series of fitting experiences may result in a fit, but no one has ever posted they've done that.
Here is what I did in trying to stop a leaking fitting at the carb fitting to line joint,
37287

rholmes
07-07-2008, 12:55 PM
You are correct, the j vents are not included in the rebuild kits. From what I read, people take a dremel to the non-marine versions and cut them at an angle opposite what from what is pictured to make it vent back into the barrels. Additionally, I believe the marine version doesn't have float adjustments, I think it is fixed.

Here is a marine version rebuilt on ebay: http://cgi.ebay.com/ebaymotors/holley-carburetor-marine-351-with-electric-choke_W0QQcmdZViewItemQQcategoryZ31286QQihZ012QQit emZ220253692629QQrdZ1QQsspagenameZWDVW

TMCNo1
07-07-2008, 01:19 PM
I do not understand why anyone in their right mind would cut off the j tubes, rendering the carb useless as a true marine application. I makes no sense and these 4160's have operated for decades with the j tubes left as originally designed for marine use.
Go ahead, and think that if fuel is blown out into the flame arrestor and leaks out instead of being dumped into the carb and you have a electric spark or short, that you won't have problems with the paramedics picking your butt out of a tree or out of the water!

T-Rager
07-07-2008, 01:44 PM
You are correct, the j vents are not included in the rebuild kits. From what I read, people take a dremel to the non-marine versions and cut them at an angle opposite what from what is pictured to make it vent back into the barrels. Additionally, I believe the marine version doesn't have float adjustments, I think it is fixed.

Here is a marine version rebuilt on ebay: http://cgi.ebay.com/ebaymotors/holley-carburetor-marine-351-with-electric-choke_W0QQcmdZViewItemQQcategoryZ31286QQihZ012QQit emZ220253692629QQrdZ1QQsspagenameZWDVW

The float level is adjusted by removing the fuel bowls and bending the needle-valve contact tab on the float to obtain the specified clearance between the top of the float body and the fuel bowl.

What you said in a previous post about tuning the carburetor describes adjusting the idle mixture. Tuning a carburetor involves optimizing many more parameters than just adjusting the idle mixture.

rholmes
07-07-2008, 01:56 PM
You learn something new everyday. I never found anything that went over the fuel bowl level modifications. Thanks for that! I guess I just hd it easy as far as my rebuild went. I purchased a used carb that needed a rebuild and I just set it up the same way old one was. Do you have a good list of tips and tricks for tuning that you can provide us for the 4160? Thanks for any help you can provide!

denverd1
07-07-2008, 02:08 PM
TMCNo1, that's exactly what I did with my new fuel line. New intake raised the carb 2" and the old line wasn't going to work. I'm sure you know that a flexible line isn't USCG approved, but any issues running a flexible line over time? I was planning to come back to rigid line, but doesn't sound like that it likely.

GuitsBoy
07-07-2008, 02:13 PM
So nobody makes a bolt in fuel line to run a 4160? Or are you saying that the only bolt in solution is to run the entire line from the tank?

BrianM
07-07-2008, 02:47 PM
So nobody makes a bolt in fuel line to run a 4160? Or are you saying that the only bolt in solution is to run the entire line from the tank?

No. You will just have to run a universal flexible line from the fuel pump to the carb instead of the hard line.

GuitsBoy
07-07-2008, 02:50 PM
No. You will just have to run a universal flexible line from the fuel pump to the carb instead of the hard line.

Gotcha, so the flexible line is not CGA, but otherwise its fine, right? Does DIM sell the complete flexible lines?

TMCNo1
07-07-2008, 03:08 PM
TMCNo1, that's exactly what I did with my new fuel line. New intake raised the carb 2" and the old line wasn't going to work. I'm sure you know that a flexible line isn't USCG approved, but any issues running a flexible line over time? I was planning to come back to rigid line, but doesn't sound like that it likely.

Boat maunfacturers and their suppliers are required by law to meet certain requirements for marine application and regulations set forth by the USCG in order to get their boats approved for sale and are covered under the NMMA that also adopts those regulations and probably more, for certification and membership. Fortunately, I had my line made by a street rod shop that makes fuel lines, brake lines, oil lines for retail sales, that is inspected, licensed to meet Federal and State DOT requirements for highway and marine use, in the type of lines and fittings that meet their requirements.
All these Go Fast, hand built or bought SK type boats out there running around with all that S/S braided plumbing, should be so equipped, but who knows, but I'm covered in my one simple application..

TMCNo1
07-07-2008, 03:11 PM
Or are you saying that the only bolt in solution is to run the entire line from the tank?

No, just from the fuel pump to the carb on a pre-EFI/Computer/electric fuel pump boat.

TMCNo1
07-07-2008, 03:22 PM
So nobody makes a bolt in fuel line to run a 4160?

Like I said in post #11, Skidim has the steel solid line for the PCM engines, but no Indmar original lines, but for the Indmar application the PCM line is 1/4" too short unless you can duplicate the PCM fittings or maybe even a PCM fuel pump from what has been posted here in the past. I just took the easiest, least expensive approved path rather than purchasing a bunch of parts hoping it would work, only to find our it wouldn't for some reason and wasting my time and money.

GuitsBoy
07-07-2008, 04:19 PM
Oh, Im dumb. Completely forgot fuel pumps wern't always in-tank. lol. Got it now. Steel braided line from the cam-driven fuel pump right in front of the oil filter. I was wondering how in the world you would install a hard line from the gas tank all the way to the carb!

rholmes
07-07-2008, 04:54 PM
"Oh, Im dumb. Completely forgot fuel pumps wern't always in-tank. lol. Got it now. Steel braided line from the cam-driven fuel pump right in front of the oil filter. I was wondering how in the world you would install a hard line from the gas tank all the way to the carb!"

That would be one long day with a tube bender, couple cases of beer and a whole lot of swearing.

denverd1
07-08-2008, 11:12 AM
So, how safe should I feel with my 3/8" rubber hose with braided steel around it? Auto Zone special...

rob935
07-08-2008, 11:21 AM
id agree with picking uo a used 4160 and rebuilding it !! i recently rebuilt my 4160 and found it to be a quick easy and cheap job to do but it has made such a positive difference to my boats performance and economy .

best of luck.

learjet2230
07-09-2008, 09:08 PM
IIRC, the factory adjustments are 1.5 turns out for air and 3/4 turn out for fuel

I'm not so sure the above is right. This is direct from Holley

The idle system supplies the air/fuel mixture to operate the engine
at idle and low speeds. Fuel enters the main well through the
main metering jet that is screwed into the metering block. Some
of this fuel is then bled off to an idle well where it is mixed with
air from the idle air bleed hole. The idle well leads directly to the
idle discharge port and the idle transfer system where this air/fuel
mixture is discharged.
Most Holley Street Performance, O.E. Muscle Car, Competition
and Pro-Series HP carburetors utilize idle mixture screws, located
on the sides of the primary metering block. These control the volume
of the pre-mixed air/fuel coming through the idle well.
Turning the screws clockwise will “lean” the idle system.
Conversely, turning the screws counterclockwise will “richen” the
idle system.
The initial adjustment is made by turning the mixture screws in a
clockwise direction until they lightly bottom. Back them both off 1-
1/2 turns. Connect a vacuum gauge to a carburetor vacuum
port that will have access to full manifold vacuum at idle. Start
the engine and allow it to warm up. Once the engine has
warmed up and the idle stabilized, the choke should be disengaged.
Adjust the idle mixture screws to obtain the highest vacuum
reading. Each screw should be turned an equal amount so
that the system is balanced.