1970 -6 Gas Tank Supply Pipe Hose Bead Question, Morphed into: “Does the OE fuel return system cool fuel going to engine?” uh … No Options

[Rufus]

Hi Folks - I have the entire fuel system out of 9140431482 back to the Webers for update, cleaning, etc. (Webers already reinstalled after thorough cleaning.) The gas tank fuel outlet pipe has no hose bead.

Is this normal? Seems odd there wouldn’t be one.

Thanks,
Bob

[Rufus]

IMHO putting the return back in will increase fuel temp; not reduce it.

[brant]

IMHO putting the return back in will increase fuel temp; not reduce it.

Nope

Fuel sitting above the motor gets hot
Having a return lets the warm fuel back into the cool reservoir of cool in the tank
The fresh fuel from the tank is cool


In racing they even sell a fuel tank you surround with ice to lower the temp further

Cool fuel makes more horsepower
Warm fuel boils and creates vapor lock

A return line absolutely cools the fuel without any doubt

Carb cars respond even better to cool fuel due to the lower pressure of a carb system

FI systems have reduced fuel boil and vapor lock due to the high pressure they operate at

A return system/line was the factory design
They did this for a reason Even on a carbed 914/6



Few people outsmart the factory engineers

[wonkipop]

IMHO putting the return back in will increase fuel temp; not reduce it.

Nope

Fuel sitting above the motor gets hot
Having a return lets the warm fuel back into the cool reservoir of cool in the tank
The fresh fuel from the tank is cool


In racing they even sell a fuel tank you surround with ice to lower the temp further

Cool fuel makes more horsepower
Warm fuel boils and creates vapor lock

A return line absolutely cools the fuel without any doubt

Carb cars respond even better to cool fuel due to the lower pressure of a carb system

FI systems have reduced fuel boil and vapor lock due to the high pressure they operate at

A return system/line was the factory design
They did this for a reason Even on a carbed 914/6



Few people outsmart the factory engineers

spot on.


the vapor lock problem in the 4s is in the short section of line between the tunnel exit and the fuel pump. (gets even worse when you do the metal line replacement of the original plastic lines - i know). solution = wrap the section of line to the pump in reflective insulation. since i have done that i have not had a vapor lock problem with the pump still in original position. the heat source that boils the fuel in a 4 is the magnesium cooling fan shroud. when you switch off after a good hot run all the residual heat in the engine conducts to the cooling fan shroud and then radiates. prime target of the radiation is those short runs of fuel line.

a 6 does not have that vicious heat radiating fan shroud.
sure there is a hot engine block, but suspect its not such a localised heat radiator.

did 6s even suffer from vapor lock?

though in fairness to the mental powers of the original engineers, they did manage to outsmart themselves with the fuel pump location of the 4 for many years until they finally gave up and admitted defeat. i guess they did not have insulated wrap back then. (IMG:style_emoticons/default/biggrin.gif)