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question on restoring '29 fuel line and fuel pump


jps
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I am hoping to get the fuel system back closer to what it originally was.  Currently the mechanical fuel pump is not connected, but there is an electric pump that is wired on whenever the ignition switch is on.  I want to re-connect the mechanical pump (I already bought a rebuilt one), add a parallel line to the electric pump with tees on both sides, and make the electric one switchable on/off as needed.  It looks like the fuel line from tank to pump is 5/16".  It also looks like new brass tubing comes in two common wall thicknesses - .014 and .029".  I am thinking of using .029" brass with compression fittings.  OK?  Or should the line be copper instead of brass? 

 

Thank you

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Copper will absorb more heat and increase your risk of vapour lock, which the '20s Buicks suffer from as standard.

Why not consider steel bundy tube instead of brass?  It will be cheaper and probably easier to bend. I would run only 1 line from the tank and have an inline electric pump ( with filter on tank side ) installed in the same line close to the tank and switchable so that you can prime the carb after car has sat for a long period.  And for giving the line a sharp boost when vapour lock sets in on a hot day.  That's how mine is set up and works perfectly.

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10 minutes ago, Rooster said:

Copper will absorb more heat

No. Under stable conditions, it will be the same as steel. But it will heat up faster - the specific heat of copper is 0.39 kJ/(kg.K) whereas it is 0.45 kJ/(kg.K) for iron, so it takes less energy to raise the temperature of a kg of copper.

 

Was the original fuel line copper?

Edited by Spinneyhill (see edit history)
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My 29 does fine with no electric fuel pump. Though not original, I prefer a high grade rubber hose between the mechanical fuel pump and the carburetor. This allows for a common , inexpensive inline fuel filter. I know of people , while trying to use the original metal tube connecting the fuel pump to the carburetor , to break either the fuel pump or the carburetor while reconnecting. This old pot metal is getting brittle. If running a new line from the tank to fuel pump I would use steel. The original tubing was brass. Copper can be very brittle and dangerous. Good luck.

Edited by raydurr (see edit history)
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4 hours ago, raydurr said:

Copper can be very brittle and dangerous.

Could you give us more information on this please.

 

Both copper and brass work harden and crack - for brass, think of hub cap skins from the mid to late 30s and the cracks in the skins around the edge. Both will harden with cold working.

 

My 1930 Dodge Brothers has a copper fuel line. My 1967 Ford Transit van had copper brake lines.

Edited by Spinneyhill (see edit history)
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14 hours ago, Rooster said:

Copper will absorb more heat and increase your risk of vapour lock, which the '20s Buicks suffer from as standard.

Why not consider steel bundy tube instead of brass?  It will be cheaper and probably easier to bend. I would run only 1 line from the tank and have an inline electric pump ( with filter on tank side ) installed in the same line close to the tank and switchable so that you can prime the carb after car has sat for a long period.  And for giving the line a sharp boost when vapour lock sets in on a hot day.  That's how mine is set up and works perfectly.

Rooster has the right idea....  My 38 Special is set up this way and works perfectly.

Edited by Mark Shaw (see edit history)
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Copper has a high heat absorbing factor.   That's why it's used in electrical installations as heat sinks ie. to take away heat from electrical components / contacts etc.

Buicks were not poor cars -- a lot of cars built in that era may or may not suffer from vapour lock depending on a heap of varients eg. ambient temperature, poor ignition timing, insufficient radiator cooling, poor fuel, road speed, road gradient, inferior mechanical design such as fuel lines installed too close to exhaust system.

And --- it gets a lot hotter in Australia and in parts of USA than New Zealand.

I agree with raydurr on the rubber fuel line, I've got that also.

All-Bus-Bars-Need-Powder-Coating.jpg

Edited by Rooster (see edit history)
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On 4/24/2018 at 12:30 AM, Spinneyhill said:

Really? They must have been pretty poor cars then! It is a wonder they sold any.

 

What has changed that makes them susceptible to vapour lock?

 

  ETHANOL!  And fuel [gas] formulated for fuel injection. NOTHING wrong with the cars. Any of them.

 

  Ben

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4 hours ago, Rooster said:

Copper has a high heat absorbing factor

Hmmm. It is a very good conductor of electricity and of heat. I wonder if the installation you show is more about large current and keeping it cook than heat absorption and radiation. Those are 690 V 200 A components, not little ones. The copper bus is required to carry that current without getting too hot, which would increase its resistance not to mention risk a fire!

 

But it won't "absorb more heat" unless the exposure is time limited.

 

So, ethanol contributes to vapour lock. I see there is a 1 psi allowance for 15% ethanol in your gasoline, which is 10 to about 14% depending on state. You have Reid Vapour Pressure rules for gasoline for the summer (May to Sept), restricting the volatility of fuel. https://www.epa.gov/gasoline-standards/gasoline-reid-vapor-pressure#information

 

The question is, how has the RVP changed from 55 or 65 RON fuel to today's fuel?

 

This article has some interesting information. http://ttypes.org/ttt2/manchester-xpag-tests-modern-petrol-volatility

Edited by Spinneyhill (see edit history)
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