Identify Carb

[GuitsBoy]

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]

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]

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]

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.

[GuitsBoy]

Originally Posted by rholmes

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]

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/HOLLE...spagenameZWDVW

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]

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]

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]

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]

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.