Fuel Lines, 5/16 or 3/8s?
 

Which size fuel line did out turcks come with?

3/8

5/16ths for the inlines, 3/8 for v8

my 71 had both. 3/8 for fuel supply line from tank and 5/16 going back to the tank for vent. had to change both to 3/8 for the TPI. Jeff.

Stelth is right. It depends on which engine it had originally.

I've found it depends on the carb. All 4bbl carbed V8's had 3/8, whereas the 307 2bbl had 5/16th. All inlines had 5/16th as well.

My 2bbl V8 has 5/16...

I put 5/16 on mine and I run a 350

Re: Fuel Lines, 5/16 or 3/8s?
 

I’m swapping to a new tank in my i6

It will eventually get a 350 so I’m wondering if I should do the 3/8 sending unit, 3/8 lines now.

However the i6 fuel pump and carb is 5/16”

Am I introducing any pressure issues for now if I do the 3/8” lines up to the fuel pump and 5/16” beyond that to the carb?

Re: Fuel Lines, 5/16 or 3/8s?
 

^ Nope.

Re: Fuel Lines, 5/16 or 3/8s?
 

The only issue you'll encounter is the fuel pumps have the same size inlet and outlet - either both are 5/16" or both are 3/8". Run 3/8" line all the way, and install a "reducing adaptor" in the line to the carburetor. While you're at it, Install a 1/4" return back to the tank and install the matching fuel pump and sending unit. The return goes a long way toward preventing vapor lock.

Re: Fuel Lines, 5/16 or 3/8s?
 

It's early and I'm not fully caffeinated yet. If a fuel pump has a return line, will that make it so that the pressure at the carburetor will not increase after the engine shuts off and gets heat soaked? I don't know how that recirc works- is it just a return line, or is there some relief valve?

Re: Fuel Lines, 5/16 or 3/8s?
 

There is no relief valve. By design, the fuel pump is "self regulating". The return port has an orifice in it. The port comes off the same chamber as the discharge port. The orifice serves to meter the amount of fuel returning to the tank. Since the return line is open at the tank end, there is no pressure build in it.. When the engine stops, the pump discharge immediately drops to zero.

Re: Fuel Lines, 5/16 or 3/8s?
 

Thanks for this information. I did a little looking around but hadn't found it.