Antisiphon Checkball - is it nessessary?
 

I'm installing a whippled 496 HO in a 94 Eliminator and I'm redoing all of the fuel plumbing. Currently there is a 90 degree brass fitting coming out of each tank, screwed into that is a barbed brass fitting that contains the check ball. The opening containing the check ball is only about 1/4" and I'm concerned about about fuel flow restriction (thats why I'm replacing all of the lines and the valve). So the question is can I just eliminate this fitting and run my fuel lines from my switching valve directly to the brass 90 coming out of the tank or will I be screwing things up? I don't really understand the purpose or function of the antisiphon device, any input would be greatly appreciated.

Get rid of the restrictive checkball assembly. You should upsize ALL fuel lines including fuel tank pickup to 1/2 inch minimum. And don't overlook your fuel tank vents either.

Antisiphon device: keeps fuel from siphoning itself into your bilge.

Picture this: your saddle tanks are mounted up pretty high. Your fuel line runs all the way down to the stringer mounted water separator. Then to the mechanical fuel pump and on up to the carb.

If your spin-on separator got loose, or your old fuel line got a crack in it, or the wrench monkey from the marina that you let winterize your boat stepped on the fuel line and pulled it halfway out of the fitting, then without the anti-siphon checkball, your entire contents of the tanks would end up in the bilge.

This is not as MUCH of a problem with a center keel tank, but if the belly tank is full, you can still siphon it all out. Especially when underway (nose-up).

If you remove the checkball, and EVER have a gasoline related insurance claim, you WILL be denied.

My advice is to buy a larger antisiphon assy that will flow the required volume of fuel.

I second what mcollinstn said , particularly the insurance part.
Also to aid fuel flow avoid drilled or cast 90*s after the fuel pump. Bent or formed 90*s are better. When you suck thru a 90 , the fuel tends to go in the directon of the suction. But when you are pushing the fuel and it hits a drilled or cast 90 it tends to back up and restrict flow due to the fact it just wants to go straight while being pushed. If you use a formed 90 , it helps redirect the flow around the bend and keeps it flowing;)

Thanks for the replys. Any ideas where I can look for larger anti siphon devices. I don't know that I've ever seen them anywhere.

Correct me if I'm wrong but isn't the checkball to prevent fuel from siphoning back to the fuel tank? This helps prevent extended cranking times after sitting. I have never seen a larger check valve for a blower application. You guys have enough paranoia for a crowd.

i made the mistake of taking them out (duel tanks)for the same reason a 700hp merlin that needed a lot of fuel. and i put in 1/2 brass n.p.t fittings and the next morning my edlebrock 130gph mechanical fuel pump was leaking gas from all around the diaphram real bad had about 5 gallons of gas in the bilge.my boat even had a mechanical fuel valve and even with it turned of it couldnt hold back all the fuel presure.i switched back to the check valves and it stoped leaking and the fuel on/off valve was able to shut off the fuel again also.i think with all the fuel being gravity fed with 90 gallons of fuel in the tank pushing was just to much pressure to hold back.i talked to imco i think they said they have a check valve with a 3/8 line which would be better than what you have at least.

You want to keep the check valve, but the problem is that it's highly restrictive and I don't know of any improved versions. It's a lose-lose situation.

HP,

consider yourself corrected.

The anti-siphon device is a USCG REQUIRED safety device. It's primary purpose is to use spring resistance to seat the ball and prevent fuel from coming OUT of the tank unless mechanical suction from a fuel pump overcomes the spring pressure.

The fact that it also functions as a one-way valve that keeps fuel from being added into the tank from that same line is a tremendously secondary benefit. Typically, the one-way valves in a fuel pump will dam up the fuel from returning back downstream without the aid of the tank's siphon device...

I've rarely been labelled as paranoid, and am usually branded an idiot for ignoring safety issues that most folks consider to be significant. Having battled gaoline fires in three boats, though, gives me a pinch of perspective into the issue.

Nimrod? Lard@ss? Bastage?
yes to all of the above.

Paranoid?
Not hardly.

OK fair enough on the valve function. Any boat I have seen or owned would have braided lines throughout and it is a much bigger concern to have inadequate fuel volume. You have had 2 fires? Are you a firefighter? j/k! Seriously though, I have had 2 insurance claims since 1988 (not related to fire) and boats were never scrutinized to find a way not to cover the claim.

I'm with mcollinstn,
I spend enough time and effort to avoid getting in trouble/sued over stupid things other people do. I dont need to add ANY stupid thing that I actually do to it.
Gary

Great input guys! I'll check out what IMCO has.

HP,

No I haven't had two fires in boats, I've had THREE fires. Two were inmy boats, one in a friend's. One was a cheap failed bronze tee in the fuel system on one of my houseboats that would have resulted in a total loss, had the A/S devices not been installed. One was a backfire into an automotive "weiand style" triangular foam air filter that caught fire and burned the rubber fuel line off the motor - where the flames came out the bilge blower vents. The friend's was due to an electrical short. All 3 fires were in the engine compartments. All 3 fires burned through fuel lines. And all 3 fires took more than one extinguisher to knock them out.

The air filter fire would have been a killer, if we hadn't had the sense to NOT open the hatch. We crammed beach towels in the bilge vents and then cracked the hatch open just far enough to blast one full extinguisher into it, then opened it and finished it off with the second extinguisher.

You seem to be of the opinion that braided hoses are indestructible, but they are NOT. Old ones crack. Hot ones melt. Sure, they're better. Not foolproof.

All I can do is give my opinions. If you want to replace your fuel system with paper sacks and plastic straws, then be my guest.

I'll still stop to help if I see you on fire...

And I'll stop to help Kokopelli when he starves his Whippled 496 and grenades it. Peace man...HP out.

There must be larger anti-siphon devices out there. How does Merc. deal with the problem on their big HP motors? What about all those 1000 and 1200 hp Sterlings out there. If they all only had 3/8" check balls we would be hearing about alot of motors running lean and blowing.

MY suggestion is that Kokopelli be hereby assigned the duty of calling two big boat builders, lets say Cigarette and Fountain and ask their rigging deptments what they do for check valves on their boats with big HP motors and then report back to us all on this thread.
Swords at rest gentleman!
Raylar;)

Check with your Aeroquip dealer. They subcontract to goodrich (in England) for large check valves. Not sure if they are the spring ball verison.

BTW be prepared to pay; size 12AN is 225 bucks

Yes, there are larger ones.
Ever seen the fuel lines for a 2000 hp diesel?

They are big.


Here's a high flow Nascar unit:
ASV08 - NASCAR 1/2” Fuel Line Anti-siphon Check Valve

USCG regulations require EITHER

a spring loaded anti-siphon

OR

an electric shutoff solenoid valve.

Choose your poison.

FYI, Insurance claims due to fire are much more heavily scutinized than others. Probably because of the possibility of arson. I know of 2 boat fires (non injury) that were investigated for months.

Alternately, use a tee and rig yourself a doohickey to use 2 of the $5 standard fittings. Double the flow capacity right there.

My boat has 4 pickup fittings in the tank. Makes it a little cleaner..

That's what I'm loooking for! Where can I order this beast?

I'm generally a bit hesitant to tell people who don't know me what I do for a living. But I'll tell you guys...I'm an insurance claims adjuster. NY State license says "Fire Adjuster" {please note, not all insurance adjusters are a$$holes}. I don't handle many boat claims, mostly large building fires. But be aware allot of ins. companies will look for an excuse not to pay a claim. Regardless of what kind of claim it is.

If you have a fire on your boat, and there is a device missing that the Coast Guard says should be there, and if the absence of that device might have contributed in ANY way to the fire, you are probably going to be SOL.

nova,

I've dealt with more intelligent and fair adjusters than morons or @ssholes. (But you dang sure remember the @ssholes forever...)

friend's Carver 450 had an electrical short and caught fire an hour after he left it docked at the dealer's marina. Other boatowners broke out the rear door and got the fire out. Boat was "nearly" totalled. There was a very detailed investigation that took two months before the insurance would allow any work to begin on the boat. Friend was out of a boat for 9 months while it got a total re-do. Says he wished it would have been allowed to sink so he could have gotten a replacement and not missed the whole freaking summer...

[QUOTE]Originally posted by Kidnova
[B]I'm generally a bit hesitant to tell people who don't know me what I do for a living. But I'll tell you guys...I'm an insurance claims adjuster. NY State license says "Fire Adjuster" {please note, not all insurance adjusters are a$$holes}. I don't handle many boat claims, mostly large building fires. But be aware allot of ins. companies will look for an excuse not to pay a claim. Regardless of what kind of claim it is.

Do Insurance companies pay financial incentives to adjusters who can reject more claims?

Well I'm going to go with one of Holley's (Earl's) check valves. They claim allmost no restriction up 150 psi and it only takes .5 psi to flow. They claim tests on 1000 hp motors with no leaning. Cost $60 from Summit.

Anyone know if Eddie Marine's electronic switching valve meets the USCG requirements for a check valve?

[QUOTE]Originally posted by 2112
[B]
2112, No. At least none that I'm aware of.

But there are adjusters referred to as "Public Adjusters" or, PA's {not sure if there is a different name for them in states other than NY}. A PA represents the insured, not the insurance company. And a PA generally works on a percentage basis. For example, say you have a fire at your house or business, you can hire a PA if you want to. Your PA will deal with your insurance company's adjuster on your behalf. If you have a loss of say 100K, it's been my experience that the PA will generally charge you between 8 and 10% to represent you, and therefore will make 8K to 10K off your claim. In NY State I believe the legal limit a PA can charge is 12.5%.