Need help to rebuild carb in one quick lesson!

[playcat]

My barge has a Volvo 5.0 I/O with a holley 4 barrel carb that is flooding like crazy! The local mech who replaced the engine 3 seasons ago can't get to it for at least two weeks, and I am tired of sitting at the dock! How can I learn how to rebuild this Holley carb step by step? Is this too big/technical a project for someone with very little engine experience?
Thanks!

[Bamaman]

Marine carbs are very simplified versions of automobile/truck carbs--made prior to 1985, that is. (Automobiles have long since gone to fuel injection.)

Purchase a carb kit, and go find yourself a good automobile mechanic. He can disassemble the carb, clean the parts and reinstall the new parts/gaskets. If you have a water muff, he can also warm up the engine on the trailer to do the adjustments to idle, etc.

Marine mechanics are just not needed on I/O engine matters. Outdrive maintenance (bellows, etc.)
is a different matter, however.

[ronb]

Finding a 'good' carburator mechanic might be a little more tricky than that, as you stated, EFI has been standard on cars/trucks starting in '85 so there aren't many automechanics that will even know how to work on them. I would start at a local speed shop (to buy the rebuild kit and new float) and ask around if there are any good carburator rebuilders (chances are if you have any circle tracks in the area there are some very skilled carb rebuild technicans)

Part of the problem with Holley carbs is that they have a lot of tunable components, which can be great for squeezing every last bit of performance out of a motor, but can be a HUGE pain if you don't know what you are doing.

Most likely you have a float or fuel pressure related issue, but to get the right guide you have to know which Holley you are dealing with. There is a set of numbers stamped into the choke horn on automotive Holley carbs, you should have some also. Then fire up google and type in "Holley (your part number) rebuild" and you should find numerous sites specific to that carb.

-ron

[playcat]

Thanks, guys. The only folks I know that have EVER worked on carbs are boat people. Even the master auto tech that lives down the block hasn't touched a carb in 10 years or so.
Any recommendations on a manual with pictures? Something like "see Dick and Jane rebuild a Holley 4 barrel"...

[badmoonrising]

I use these guys:

http://flyingfishcarburetors.com/

Quick turnaround and the Mercarb they did for me back in 2006 for my Starcraft hasn't had a single issue. Lots of marine carbs have the idle mixture screws blocked and these guys will remove that and fine turn your carb. Auto mechanics will remember how much we all had to do this but not tel the EPA (It made engines runs very poorly and lean when the vehicle was 3-4 years old).

[ronb]

http://www.holley.com/data/Products/Tec ... R10013.pdf

And this article..
http://www.chevyhiperformance.com/howto ... index.html

There are things you can do yourself..
http://www.youtube.com/watch?NR=1&v=ge- ... =endscreen

good luck.
-ron

[Shopguy]

<--- Holley guy. Done my share of work on them. Would be glad to assist if you have any questions.
Holley is probly the easiest carb to rebuild next to the AFB.

[Shopguy]

Couldn't help myself , had to come back to this one and just say that Massive flooding is usually caused by three things on the Holley.
One, the choke blade is not opening during warm up. If the blade is standing open then,
Two, If you look down the top of the carb and see fuel dripping from the boosters, The float needle (s) are stuck open. Usually from trash or rubber from the inside of fuel lines.
Three, I've seen guys pull the float needles a dozen times looking for trash and not change the orings that go around the needle housings themselves. These orings will shrink over time or get damaged from taking them in and out too much and start to bypass the needle.
Okay there's four, The power valve could be blown, from a backfire or spit back thru the carb ...Or... it dried out like rubber does and just cracked. If there's no fuel dripping from the boosters Change the power valve....straight shot down the intake.

There... I said it.

[GregF]

Is this just a case of gas pouring in from the bowl? You may just need a float. They do go bad and they still look fine, they just won't "float".
They get saturated with gas.

[playcat]

Thanks to shopguy and GregF; y'all are right on. gas just keeps on coming out of the bowls unless i turn off the key, then it drains till the bowls pretty much empty. So i need to pull off the bowls and replace floats, needle valves and o-rings, possibly power valves (may as well since I got it apart). Sound about right? i have not found teh carb floats yet since it seems there are two types on the 4150...either way, I'll get the parts from Holley direct.

Tech said he MIGHT be able to get to it this week, maybe. If I try to do this, the worst that could happen is I bring him a bag of parts to dump on his bench and say, "Have fun!"

That and the Admiral has me walk the plank for real. Slip rent is mighty expensive when the boat can't leave it...
Thanks again!

[Bamaman]

It's hard to believe any good auto mechanic couldn't do this simple job. Virtually every drag car and truck pull engine's still running carbs--most often Holleys.

I've always rebuilt my own carbs, and I'm no mechanic. It's a piece of cake as long as the carb is not a high tech emissions carb. I once rebuilt my Mazda RX7 4 barrel, and only had 3 little pieces leftover--and it even ran great.

The carb. kit on my 80's 4 cylinder Mercruiser inboard outboard was straight from a 1967 Chevy Impala 307 cu. in. engine. That tells you about Mercruiser's outdated technology.

I cleaned the two carbs on my 1985 Yamaha 115 hp 2 stroke last year--second cleaning in 26 years. If you don't tear a gasket, no carb kit is needed on a 2 stroke. The job didn't take but 1 hour, including pulling and reinstalling. A Yamaha repair manual was the best purchase I ever made.

The boat mechanic previously mentioned in this thread could also rebuild and reinstall the Holley carb. in an hour flat--if he really wanted to.

[playcat]

The boat mech does know carbs; he built them for Merc Racing for guys like Reggie Fountain, Don Aronow and other factory projects. The problem is he is about two weeks behind on other jobs...hope he finds himself waiting on some parts so he can get to me.

[ronb]

A GOOD carb tuner is getting harder to find. Think about the age of the workforce.. The average oil change guy starts working at 18yrs old (that would mean he was born in 1994) an old mechanic (say 28) would have been born in 1984. If EFI started being implemented in '85, then for an average automechanic, carbs are getting to be very old technology. Back when I did autowork for a living (up until '99) I would rebuild my own carbs, well I still do, currently I have an autolite 1100 1bbl in my carb tank for an inline 6cyl tri-power project.

Every time I get ready to rebuild I carb I am reminded of this description of how carbs work. The story goes by a few titles depending on where you find it.. I have shamelessly borrowed it from a snowmobile website and changed a few words...

These are 3 other examples of how this story has been modified.. (no real reason to read them, the jist is below)
http://www.snowmobilefanatics.com/forum ... -explained (snowmobiles -- where I copied it from)
http://www.saskma.com/content/view/611/56/ (motorcycles)
http://www.aerostich.com/media/readings ... carbs.html (also Motorcycles -- this may be linked to the origin of this tale..)

The basic secret of carb function is that inside each carb are thousands of tiny gnomes; each with a small bucket. As you open the throttle, more of these gnomes are allowed out of their house and into the float bowl, where they fill the buckets and climb up the carb's passages to the intake, where they empty their buckets into the air stream. But, if you don't drive your pontoon for a while, bad things can happen.

Tiny bats take up residence in the chambers of the carb, and before long the passages are plugged up with guano. This creates a gnome traffic jam, and not enough bucketfuls of fuel can get to the engine. If it gets bad enough, the gnomes simply give up and go take a nap. The engine won't run at all at this point. Sometimes you'll have a single dedicated gnome still on the job, which is why the sled will occasionally fire as the gnome tosses his lone bucket load down the intake.

There has been some research into using tiny dwarves in modern carbs. The advantage is that unlike gnomes, dwarves are miners and can often re-open a clogged passage. Unfortunately, dwarves have a natural fear of earthquakes, as any miner should. In recent tests, the engine vibrations caused the dwarves to evacuate the Evinrude test vehicle and make a beeline for the nearest Yamaha dealership. Sadly, the Yamahas were fuel injected and so the poor dwarves met an unfortunate end in the rollers of a fuel pump.

Other carb problems can also occur. If the level of fuel in the float bowl rises too high, it will wipe out the poorer gnome housing in the lower parts of the carb. The more affluent gnomes build their homes in the diaphragm chamber, and so are unaffected. This is why the bike is said to be "running rich".

If the fuel level drops, then the gnomes have to walk further to get a bucket of fuel. This means less fuel gets to the engine. Because the gnomes get quite a workout from this additional distance, this condition is known as "running lean".

The use of the device known only as the 'choke' has finally been banned by PETG (People for the Ethical Treatment of Gnomes) and replaced by a new carb circuit that simply allows more gnomes to carry fuel at once when the engine needs to start or warm up. In the interest of decorum, I prefer not to explain how the 'choke' operated. You would rather not know anyway.

So thats how a carburetor works. You may wish to join us here next week for basics of electricity or, "How your pontoon creates cold fusion inside the stator, and why the government doesn't want you to know about it"

-ron

[Shopguy]

If you decide to take it on yourself, I've found the individual parts on the wall at our local parts stores for the 4150. floats, needles and bowl gaskets , etc. use a little spray lube, or light coat of grease, any kind, on the o rings and gaskets. Makes it easy to go back in for a change later on.
If you dropped that much fuel down the tubes , might want to change the oil afterwards.

Was the fuel dripping from all four boosters or just the front?

I had a fuel line deteriorating one time, caused me fits.

If you pull the needle out, lift it straight out of the bowl and look at where the needle contacts the seat to see if anythings in there causing it to stick. If not, check to see that the o rings around the needle housing are not damaged or shrunk below the diameter of the housing allowing fuel to get past. Sounds like you have an electric fuel pump. When you put the needles back in there should be some resistance because of the o rings being a bit snug down the hole. (lube). Take note of the depth of the needle housing before removing. When you pull the big slotted screw on top or the if you have the hex nut on top, notice how many threads of the housing are visible. That's a good place to start when you go back together with it. DO NOT run the needles all the way down. You'll bend the floats. just put them back close to where they were.

Once again if you had fuel from all four boosters all of a sudden then you should check the fuel pressure just in case your regulator is jacked. I can't give a spec but I don't think you should see more than 6-7 lbs at the carb.

[playcat]

Thanks everyone. Where would I find the regulator? between the fuel pump and the carb, right?