Carburetor heat soak or vapor lock?

[Sixpactogo]

I'm trying to educate myself on return line size needed. I'm currently running a 1/4" return and 3 nipple filter with small ID orifice return connection with my Quick Fuel carb. In reading the Aeromotive FAQ, they say that minimizing vapor lock by keeping fuel cool and flowing requires a 3/8" return line for my setup using a mechanical fuel pump. If that's true, why do the 3 nipple fuel filters have the small ID orifice to restrict flow?

With a larger orifice in the return, there is concern of starving the engine by sending too much fuel back to the tank. I have no idea why someone would require a 3/8" return. Mopar design engineers installed the 1/4" return like you have for the very reason of minimizing vapor lock. You should quiz Aeromotive to see if it is a typo.

 

[68 Sport Satellite]

With a larger orifice in the return, there is concern of starving the engine by sending too much fuel back to the tank. I have no idea why someone would require a 3/8" return. Mopar design engineers installed the 1/4" return like you have for the very reason of minimizing vapor lock. You should quiz Aeromotive to see if it is a typo.

This is in the Aeromotive 13301 fuel pressure regulator installation instructions. Now, if you're not using a regulator, then I would agree the return line could be smaller, but with the regulator controlling system pressure, it's supposed to be return line is equal to or larger than the supply line.

 

[68 Sport Satellite]

I have a 1/4" return.

are you using a regulator or no?

 

[dfrazz]

are you using a regulator or no?

No regulator, stock mechanical fuel pump.