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By Outlaw56 - 8 Years Ago
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Is there a standard for fuel line diameter in Y-Blocks? Does HP or distance from tank to fuel pump? Is diameter from tank to fuel pump and fuel pump always the same?
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By GREENBIRD56 - 8 Years Ago
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The run from the tank to the fuel pump is powered by a vacuum (produced by the pump). So - with a perfect vacuum at sea level, the maximum "pressure" forcing fluid to flow toward the pump can't exceed 14.7 pounds per square inch. But the pump won't produce anything close to "perfect vacuum"....... so the pressure is considerably lower. The larger the line the better when dealing with a pure suction sort of feed. 3/8 is a nice number for the tank to pump line.
The line from the pump to the carb is a "positive" pressure - and the "absolute" pressure is what you would see on a standard gauge - plus the 14.7 atmospheric so easily close to 20 "absolute". Pressurized by this sort of force, 5/16 line does a fine job - even with filters and elbows and a needle orifice in the carb.
These sizes have always worked rather well on "street" cars with relatively stock engines.....
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By miker - 8 Years Ago
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Steve, pm sent
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By paul2748 - 8 Years Ago
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Factory called for 5/16 lines all the way. E and F cars may have been different
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By Outlaw56 - 8 Years Ago
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I'm thinking either 5/16 or 3/8 will work for a stock Y block. If It has over 300 HP, probably lean more towards the 3/8". Reason I'm asking is cause I'm investing in some Rigid model 600 benders and I want to minimize the cost of tools. I recently purchased a 3/16 and fell in love with it for brake lines. I have one rear dually rear axel that will take a 1/4 line so will just do nickel copper on that one and then look at either a 5/16 or 3/8 (or both) for fuel lines. Was hoping to just get one or the other.
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By Outlaw56 - 8 Years Ago
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GREENBIRD56 (3/31/2017)
The run from the tank to the fuel pump is powered by a vacuum (produced by the pump). So - with a perfect vacuum at sea level, the maximum "pressure" forcing fluid to flow toward the pump can't exceed 14.7 pounds per square inch. But the pump won't produce anything close to "perfect vacuum"....... so the pressure is considerably lower. The larger the line the better when dealing with a pure suction sort of feed. 3/8 is a nice number for the tank to pump line. The line from the pump to the carb is a "positive" pressure - and the "absolute" pressure is what you would see on a standard gauge - plus the 14.7 atmospheric so easily close to 20 "absolute". Pressurized by this sort of force, 5/16 line does a fine job - even with filters and elbows and a needle orifice in the carb. These sizes have always worked rather well on "street" cars with relatively stock engines.....
If I want to purchase just one bender, will either 3/8 or 5/16 work for complete fuel run?
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By GREENBIRD56 - 8 Years Ago
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On my own outfit - I have a 3/8 line from the tank forward - and 5/16 to the carb. Depending on complications (fittings and so-on) 3/8 up to the carb would work. It would take very soft annealed 3/8 tubing to avoid kinks. What I really think is the key - is a generous sized tank line when using a mechanical suction pump.
This graphic shows what you get out of a Holley 80 GPH mechanical pump. To make 300 HP you must provide flow equal to about 30 gallons per HOUR when the engine is at the peak rpm. The free flow rating of the pump is useless data - you have to have the necessary flow at 4 -5 psi for the Holley carb to be feeding the horses - read the RED line of the graph. I'm using a Ford FE pump intended for a 335 HP Police Interceptor engine - and it provides a same or similar curve to this Holley pump. Anyway the provision of 1/2 gallon in one minute - at pressure - is easy to get through a 5/16 line.
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By paul2748 - 8 Years Ago
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Yes, either will work.
Outlaw56 (4/4/2017)
If I want to purchase just one bender, will either 3/8 or 5/16 work for complete fuel run?
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By Outlaw56 - 8 Years Ago
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Thanks for the help. If I understand correctly, I cant go wrong with 3/8. I think my next bender will be the 3/8 for fuel lines. I have the 3/16 for brake lines and love it.
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