Fuel lines size?

[lexxman]

Hi,all. I'm getting ready soon to start putting the car back together. Its a 69 with a 383, and a friend and I were talking about fuel line and sending unit the one I have has a 5/16 pipe. My friend thinks I should change it to 3/8 line. How much difference will it make? At this point it just means I would have to exchange the sending unit.

[myk]

Some of the veteran members of this board will point out that there are 1,000 horsepower applications running with the 5/16'ths lines with no problem.  

I changed out my 383 car's lines to 3/8'ths to feed the 440, but it certainly isn't necessary-do it if you want to.  I certainly didn't notice a difference in performance between the two lines...

[green69rt]

I would think it is more important to get the return line installed, it's only 1/4" (I think?)  If you're going for max HP then the 3/8" line is important.

[c00nhunterjoe]

If you are sticking with a mild motor then your line will supply it just fine. Up to 400hp is my reccomendation on the 5/16 line.

[green69rt]

If you are sticking with a mild motor then your line will supply it just fine. Up to 400hp is my reccomendation on the 5/16 line.

Yeap.

[don duick]

I installed an electric cutout in my fuel line as a security device. it got blocked as I did not have a filter in my sender unit. when I removed the 5/16 fittings to clean it I discovered it only had a 3/16 hole. This supplied a mild 440 mostly cruising, occasional 5000 rpm shifts and a couple of dyno runs. I drove with this for 2 years. I have now removed it. I think you need a big cube high horsepower motor to warrant the use of a 3/8 line.   

[lexxman]

If you are sticking with a mild motor then your line will supply it just fine. Up to 400hp is my reccomendation on the 5/16 line.

This is what I was thinking. My engine is pretty close to stock,8 1/2 to 1 with a purple mopar cam. Stock 906 heads,just a basic 383. My friend like to change thinks,cause he thinks it will be better. If I was running high powered motor I could see it, but I think I will stay with the 5/16 line.

[Dino]

The return line would be the only benefit.  Keep the 5/16 if you don't need a return.

[lexxman]

I was thinking about adding a return line,the sending unit doesn't have one. What be involved in adding one?

[Dino]

I was thinking about adding a return line,the sending unit doesn't have one. What be involved in adding one?

Two ways:

Get another sending unit and be forced to switch to a 3/16 inlet, or drill a hole in the disc of the unit you have and weld a return in place.  It's very easy to do the latter.  I would have done it on mine but my lines were old so it made sense to get the bigger ones with a new sender.

[69wannabe]

If you are running a 383 the 5/16 should be plenty. I ran the 5/16 line on my charger even after I swapped up to a 440. It was a very healthy 440 with bigger valves in the heads and RPM intake and a holley 750 DP carb and the smaller line worked fine. I had a carter street pump on there and had 3/8 line from the pump to carb tho... After I swapped to the 493 I put the larger 3/8 line on there just to be sure because of the more cubic inches and went up on the carb to an 850 DP.

[lexxman]

I think I will stay with the 5/16 line.  I have the stock carter 4bbl and I figure itsrunning about 350 hp. I won't be racing it or anything,just driving and enjoying.

[c00nhunterjoe]

Fwiw, i dont run a return on my 383.

The 1st 440 in my belvedere was "mild" 10:1, 509 cam, mild ported 906's and on 5/16 line it ran out of fuel at the top of 2nd with the high flow mechanical pump. Switched it to a cell with 1/2" line and elec pump. Granted that was overkill, but it was planned to get a bigger engine anyway.