I'm planning on replacing on the copper fuel lines on my 28 and i have a few issues. I had planned on putting in new copper but i've repowered with new fuel injected 350's and i'm kinda learly replacing with the orginal size line which is 1/4" id. Id rather use 3/8" id. Is this overkill? Even if i went to 3/8" the shutoff valves are 1/4" id and the same with fittings in the racor. Anyone ever have any issues using 1/4" id line with 5.7efi's?
Thanks in advance for your help.
Fuel Line Question
Moderators: CaptPatrick, mike ohlstein, Bruce
Yes.
EFIs require a higher fuel flow that 1/4 won't handle. 3/8 is the minimum size and I wouldn't use copper.
Use the red stripe CG rated hose. If your engines have a return line instead of a recirculating system, use 3/8 on that also.
Replace all fittings so that you maintain 3/8 id.
Do not plumb the return line into the fuel pickup.
EFIs require a higher fuel flow that 1/4 won't handle. 3/8 is the minimum size and I wouldn't use copper.
Use the red stripe CG rated hose. If your engines have a return line instead of a recirculating system, use 3/8 on that also.
Replace all fittings so that you maintain 3/8 id.
Do not plumb the return line into the fuel pickup.
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scooter28
i was kinda hoping you weren't gonna say that of course i already recieved new shutoff valves that were a replacement to the orginals and them things ain't cheap. I was planning on running the copper to the bulkead wall then running rubber from there to the filters/pump. Is there a reason not to use the copper if i did it like that it would save 20ft of rubber which at 2.00 plus a foot is well another 40 bucks.lol also i had planned on plumbing the return lines into the same plate the vent comes from. thanks for the quick reply bruce
One main reason for not using copper on high flow gas systems is heat absorbsion and the real possibility of boiling the fuel and vapor lock.
Rubber is an insulator.
The other is fracturing from vibration. I use copper tubing all the time and the quality is not what you got 25 years ago by far in my opinion.
Add to that gasoline and well you determine how important those on the boat are to you.
Scot,
That depends on the flow rate of the fuel delivery system, not just the burn rate.
Todays modern diesels using 3/8 on 325hp is okay. Anything higher and I'd go to 1/2.
Older 2 cycle DD engines used the fuel to help cool the engine and had very high flow rates, IE 80 gal/hr at cruise vs the actual burn rate of 40 gal/hr.
This requires a larger id fuel line.
Match the fuel line size to the flow rate, not burn rate.
Rubber is an insulator.
The other is fracturing from vibration. I use copper tubing all the time and the quality is not what you got 25 years ago by far in my opinion.
Add to that gasoline and well you determine how important those on the boat are to you.
Scot,
That depends on the flow rate of the fuel delivery system, not just the burn rate.
Todays modern diesels using 3/8 on 325hp is okay. Anything higher and I'd go to 1/2.
Older 2 cycle DD engines used the fuel to help cool the engine and had very high flow rates, IE 80 gal/hr at cruise vs the actual burn rate of 40 gal/hr.
This requires a larger id fuel line.
Match the fuel line size to the flow rate, not burn rate.
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scooter28
thanks again bruce. i went ahead and ordered new valves and 50ft. of 3/8 hose today i want to do it right the first time so i took your advice. lol My biggest worry is i hate using hose clamps for fuel connections. I dont even use em for cars that i work on much less a boat. I know its perfectly fine but just never have trusted them. I will be getting awab clamps for sure on the fuel line.
So then on a pair of 315 cummins you would recommend 3/8? Any good source to order it on line? I am getting to that stage myself.
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Don't ever think less is more:
When we redid CHIMERA the fuel lines were set at 5/8" intake and 1/2" returns. We used M1000 "primary" racors then to the fuel block for distribution to the Cummins OEM fuel filter. Our engine horsepower is rated at 330hp.
In my opinion there is no overkill when it comes to fuel buffering and delivery (read as: the more filter area and the easier fuel sucks through the hose the better). The same goes with back pressure. None is better than some. If its rated at 5" make it 6" and know you'll have no issues.
Does it work?????? Talk to me in 9 years. Right now its been 4 and we just start the motors and go (to early to tell IMO)
AIR, FUEL, OIL, WATER, right sized props-all of this ='s long living diesels
We all know this, it seems every once in a while the wallet tries to tell the big head what to do..... If the little head was a boater and not a cave dweller we wouldn't have this problem
When we redid CHIMERA the fuel lines were set at 5/8" intake and 1/2" returns. We used M1000 "primary" racors then to the fuel block for distribution to the Cummins OEM fuel filter. Our engine horsepower is rated at 330hp.
In my opinion there is no overkill when it comes to fuel buffering and delivery (read as: the more filter area and the easier fuel sucks through the hose the better). The same goes with back pressure. None is better than some. If its rated at 5" make it 6" and know you'll have no issues.
Does it work?????? Talk to me in 9 years. Right now its been 4 and we just start the motors and go (to early to tell IMO)
AIR, FUEL, OIL, WATER, right sized props-all of this ='s long living diesels
We all know this, it seems every once in a while the wallet tries to tell the big head what to do..... If the little head was a boater and not a cave dweller we wouldn't have this problem
KR
JP
1977 RLDT "CHIMERA"
JP
1977 RLDT "CHIMERA"
If you use proper barbs sized to the hose, it should be a tight slide on fit.
After that the use of ABA (almost 100% clamping pressure)or the like clamps will give you no problem.
In all the years in doing and repairing all the fuel systems I've been involved with I've never had a failure with proper sizing of hose and fittings and using the full contact style clamps.
Andre,
The problem even with those clamps is the design. The worm and corresponding slots reduce the surface area against the hose. They also allow the worm to cut into the hose.
Fractures occur quite often at the edges of the slots from the stress of the worm pulling it tight.
After that the use of ABA (almost 100% clamping pressure)or the like clamps will give you no problem.
In all the years in doing and repairing all the fuel systems I've been involved with I've never had a failure with proper sizing of hose and fittings and using the full contact style clamps.
Andre,
The problem even with those clamps is the design. The worm and corresponding slots reduce the surface area against the hose. They also allow the worm to cut into the hose.
Fractures occur quite often at the edges of the slots from the stress of the worm pulling it tight.
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CaptPatrick
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The ABA and AWAB companies merged in 1990, so usually now, the clamps are stamped & sold under the AWAB name. The are Swedish manufactured and the AWAB Ultra is made of 316 SS.
The AWAB clamps are widely recoginized as the best available and come in several other configurations other than the Ultra. (See: http://www.abamarine.com/aba-mar-specs.html and http://www.hweckhardt.com/clamps/ABAMain.htm)
Those pictured here are on Patrick Hancock's B31...
The AWAB clamps are widely recoginized as the best available and come in several other configurations other than the Ultra. (See: http://www.abamarine.com/aba-mar-specs.html and http://www.hweckhardt.com/clamps/ABAMain.htm)
Those pictured here are on Patrick Hancock's B31...
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