Fuel line questions

[52cranbrook4]

I had a question regarding fuel lines... stock lines are 5/16" and I was curious if reducing them to 1/4" would be bad. I have a few sticks of 1/4" stainless I wanted to use if possible for new lines. I'm also running a small electric fuel pump just outside of the tank then running it into the manual on the block. Thanks in advance. 

[Branded]

My own feeling on this is, I wouldn't go smaller, if any thing I would go with 3/8 if you need a new fuel line.

[desoto1939]

I would also agree to stay the same but not smaller.  Also consider using the newer copper nickel ines they are easier to bend then the old steel lines.

 

Rich Hartung

[maok]

I wouldn't worry too much, unless you are racing your rig. Your electric fuel pump will supply plenty of fuel with 1/4" lines.

[DJ194950]

I agree with maok.

With an electric pump if mounted close to the tank always on when running, pushing the gas as compared to a manual pump pulling all the way from the tank  I really doubt you could possibly run out of fuel to the manual pump.

Even if the manual pump quit working you may not even know it- many have said the electric will push fuel through the manual pump and still supply fuel to the carb.

DJ

[52cranbrook4]

Maybe I should have included I'm keeping my stock flathead 218.... 

[52cranbrook4]

6 minutes ago, DJ194950 said:

I agree with maok.

With an electric pump if mounted close to the tank always on when running, pushing the gas as compared to a manual pump pulling all the way from the tank  I really doubt you could possibly run out of fuel to the manual pump.

Even if the manual pump quit working you may not even know it- many have said the electric will push fuel through the manual pump and still supply fuel to the carb.

DJ

I've never changed out fuel lines before and like I said I have the 1/4" stainless already. Now the next big question is flare or compression fittings?

 

[Los_Control]

Not sure what others have done with electric fuel pumps, sure you need a regulator also. Think carburettors like 5-7 pounds pressure.

I asked the same question about fuel line size. The original fuel line is 5/16", but the brass fittings and fuel pump connectors are all 1/4" or 3/8".

I never measured them, just saying they are smaller then 5/16" And the larger line dropped down to a smaller size fitting, I really dont think would be much difference, if was just kept all at the same smaller size.

Since I have to buy line any ways, will stay with the 5/16" and use the existing brass fittings I already have. Also the 5/16" looks better with more girth and may be stronger against breaking from vibrations and movement.

Just not convinced it is supplying more volume with the restricted fittings.

[52cranbrook4]

1 minute ago, Los_Control said:

Not sure what others have done with electric fuel pumps, sure you need a regulator also. Think carburettors like 5-7 pounds pressure.

I asked the same question about fuel line size. The original fuel line is 5/16", but the brass fittings and fuel pump connectors are all 1/4" or 3/8".

I never measured them, just saying they are smaller then 5/16" And the larger line dropped down to a smaller size fitting, I really dont think would be much difference, if was just kept all at the same smaller size.

Since I have to buy line any ways, will stay with the 5/16" and use the existing brass fittings I already have. Also the 5/16" looks better with more girth and may be stronger against breaking from vibrations and movement.

Just not convinced it is supplying more volume with the restricted fittings.

I don't think vibration will play a role with the stainless. But to be safe I picked up 20 feet of 5/16 stainless just a bit ago. Really don't want to do the flare game so I'm debating compression fittings but can flare if have to... 

[knuckleharley]

5 hours ago, 52cranbrook4 said:

I had a question regarding fuel lines... stock lines are 5/16" and I was curious if reducing them to 1/4" would be bad. I have a few sticks of 1/4" stainless I wanted to use if possible for new lines. I'm also running a small electric fuel pump just outside of the tank then running it into the manual on the block. Thanks in advance. 

I am GUESSING  a smaller ID fuel line would automatically equate to more fuel pressure,which would require a fuel pressure regulator inline. There may even be other issues involved like early fuel pump failure from the increased pressure,but I'm just guessing about that and probably wrong.

[knuckleharley]

2 hours ago, desoto1939 said:

I would also agree to stay the same but not smaller.  Also consider using the newer copper nickel ines they are easier to bend then the old steel lines.

 

Rich Hartung

Not to mention a  LOT easier to bend without kinking than stainless lines.

[knuckleharley]

44 minutes ago, DJ194950 said:

I agree with maok.

With an electric pump if mounted close to the tank always on when running, pushing the gas as compared to a manual pump pulling all the way from the tank  I really doubt you could possibly run out of fuel to the manual pump.

Even if the manual pump quit working you may not even know it- many have said the electric will push fuel through the manual pump and still supply fuel to the carb.

DJ

I see the smaller fuel lines equating to MORE fuel pressure,not less. The fuel pump is going to pump at the rate it pumps,but with the same volume going down lines with a smaller ID,the fuel pressure out the far end has to be higher than before.

Or am I wrong about this?

[Los_Control]

10 minutes ago, knuckleharley said:

I see the smaller fuel lines equating to MORE fuel pressure,not less.

I also thought the same, but if a inline fuel pressure regulator was installed, and probably should have one any ways, would think it to be ok.

Edited February 1, 2017 by Los_Control

[DJ194950]

Putting flares on SS lines is a real PITA. Regular flaring tools do Not cut it... Leaks,leaks,leak! That SS is hard, but can be bought only in a few places that is a softer SS line which helps. Saw it somewhere in a mag.- but where?- Do not remember.

I tried to help a friend with SS fuel and brake lines on a 55 C. car several years ago. He finally bought a $200 plus line flare tool from Eastwood that finally resoved the flaring issues. Dry lines-Finally!

Using compression type fittings may work?-never tried it.

ISS lines do get used a lot on special built cars etc. and they seem to use a 37 degree flare on adapter fittings with a Tube nut  and sleeve over the line and under the nut (usually aluminum) that makes sealing much easier- But gets $$ expensive!

A trail run with compression fittings on some small pieces and let us all know?  I would appreciate that myself.