3/8 or 5/16 Lines

[darrin75]

383 Engine
750 Holley carb
452 heads
509 cam and lifters

I have 5/16 sender and fuel line. My questions are, Is this enough fuel line for this set-up, should I go to the 3/8 set? It Seems that my car wants more fuel, although It is a fresh rebuild and has not been really broke in yet. Any advantages to going with the 3/8 set up over stock 5/16 lines and sender. The 5/16 is what was in the car when It had a 318 in it. Am I getting enough fuel. Also Who recommends electric fuel pump over manual pump? Any great upgrade there? Thanks

[gtx6970]

depends on the rpm range it's gonna live in

upgrading to 3/8" is not going to hurt it in any way, but may not be needed or worth the costs involved

[Purple440]

darrin75, I'll just share my experience and it might help you decide:

I have a 440, and at one point it was a 5/16 sender and lines, and a stock mechanical pump.  My power died off after about 4500 rpm.  This spring I installed a Carter 120gph pump and 3/8 sender and lines.  With that change alone I got power through 6000rpm so I was very happy.  Regarding the electric pump, I went with another mechanical pump that put out more volume and it was just a simple swap.  With an electric it may take more work/time assuming you have a mechanical now, for maybe no advantage unless your racing.

Maybe it depends on your RPM range.  My cam gives me a range of 2500-6000rpm.

P.S.  My car had a 318 in it also before swapping in the 440.

[firefighter3931]

A 5/16 line with a good quality mechanical pump will support 500hp no problem. In your case i would keep what you have and invest in a high volume Carter mechanical (6psi) street pump. Check the fuel pump pushrod while you're at it.....it should measure 3.25in....if not...replace it when you do the pump. 



Ron

[Purple440]

Ron is that for a 383 and/or 440?  Do you think I would have been ok with 5/16 lines but the HV pump?

[GreenMachine]

5/16" lines are fine for your application, just get a higher volume mech. pump.

[firefighter3931]

Ron is that for a 383 and/or 440?  Do you think I would have been ok with 5/16 lines but the HV pump?

Purple, doesn't matter what engine....in the 500hp range that line is fine. In fact i have a buddy who ran mid 10's with a roller cammed 440 and HV mechanical pump....no problems. Oh ya....the car was originally a 383 with the 5/16 pickup and fuel lines. 


Ron

[Purple440]

I guess I should have asked before I replaced my 5/16...that was a pain in the ass.     Yeah mine was a 383 car too even though I got it with a 318.

Oh well, that's one less thing to do when I put my Roots blower on 

[4cruzin]

I would change it out anyways . . . better too much than too little when it comes to gas flow!   

[Nacho-RT74]

from factory all 440s were 3/8, but I'm agree 5/16 is enough even for a 451 stroke, at least on street use, maybe not race.

I just bought a ne fuel sender 3/4 with 1/4 retunr line. I will plug on my stock 5/16 and just will upgrade the fuel line IF I notice is not enought to my very future 451   VEEERY FUTURE IT SEEMS

[sean68charger]

from factory all 440s were 3/8, but I'm agree 5/16 is enough even for a 451 stroke, at least on street use, maybe not race.

I just bought a ne fuel sender 3/4 with 1/4 retunr line. I will plug on my stock 5/16 and just will upgrade the fuel line IF I notice is not enought to my very future 451   VEEERY FUTURE IT SEEMS

i disagrre with you that all 440`s came with 3/8. my genunie 68 R/T had 5/16 fuel line, i changed it a few weeks ago and it was the original one i swapped out

[Nacho-RT74]

well... it is what does appear stated on Mopar manual catalog

[Steve P.]

I agree with Ron that a 5/16 line can keep with your motor, but I prefer a very large line with a regulator and return line to the tank. This becomes more of a necessity with higher HP and in hotter areas of the country. With the excess fuel being returned to the fuel tank you stand less of a chance of vapor lock as the fuel normally stays cooler. You will have plenty of fuel at the ready with the larger line. You will also work the fuel pump less hard with a by-pass. Mechanical or electric pump. 

There are many trains of thought on this subject, but every HIPO manufacturer will tell you bigger is better and return lines are a big plus. 

Ask VegasMike about high temps without a return line..

[darrin75]

Best HV mechanical pump? I want more fuel?

http://store.summitracing.com/partdetail.asp?part=CRT%2DM5903P&view=1&N=700+

Also If I got this I assume I need no regulator or gauge, and what fittings do I use for 5/16 line?

[darrin75]

383 Engine
750 Holley carb
452 heads
509 cam and lifters


With these spec should I have the vaccum advance plugged off???

[Ghoste]

Yes.

[Rolling_Thunder]

I had a 5/16" fuel line with a mechanical pump...      with a 383...    starved out at high RPMs...    i didnt like it...    so now im running -10AN and -8AN lines   

[Steve P.]

If you have enough power to pull the front wheels off the ground you better have a good electric pump with large volume and return line.  You know that feeling of being slammed back or pinned into your seat?? Well fuel is no different. While you are being pinned to the seat your fuel is too. It is trying to run back to the tank. Imagine sitting in the passenger seat of your car with someone else driving it. He stands on the go pedal from a dead stop, BUT,,,,,  SOMEONE PULLED YOUR SEAT BOLTS... Where are you going?? 

Standard every day drivers from the factory where never set up for this scenario. Most of the time you can get away with a 'like factory' set up.   You better have big fuel bowls and set up right..  True 1/4 mile cars that starve the motor for fuel lose.. If this wasn't true, (RACE CARS), would never bother with electric pumps and the added cost of the fuel regulator and lines..   

[darrin75]

Ron is that for a 383 and/or 440?  Do you think I would have been ok with 5/16 lines but the HV pump?

Purple, doesn't matter what engine....in the 500hp range that line is fine. In fact i have a buddy who ran mid 10's with a roller cammed 440 and HV mechanical pump....no problems. Oh ya....the car was originally a 383 with the 5/16 pickup and fuel lines. 


Ron

This guy seems to thing I will be fine with this set-up.  He seems to know lot about engine specs.

[Nacho-RT74]

IMHO, don't get a headache about... change in a future JUST IF YOU FEEL that you are needing. But when you need a fuel sender you can start getting a 3/8 fuel sender with return line anyway, will be just a step ahead and price is the same than 5/16 unit. I'm doing it.

[Steve P.]

Ron is that for a 383 and/or 440?  Do you think I would have been ok with 5/16 lines but the HV pump?

Purple, doesn't matter what engine....in the 500hp range that line is fine. In fact i have a buddy who ran mid 10's with a roller cammed 440 and HV mechanical pump....no problems. Oh ya....the car was originally a 383 with the 5/16 pickup and fuel lines. 


Ron

This guy seems to thing I will be fine with this set-up.  He seems to know lot about engine specs.

Ron absolutely know a thing or two about building.. No doubt about it.. There is very, very little that we don't agree upon. If I sound like I don't agree with him I'm sorry. I don't always print what I am thinking.. What I am saying here is that all cases are different. If your building a street cruiser with a fairly healthy motor you can get away with allot. If you go back and read what I have wrote you will see that I am merely pointing out a few points. I don't know your exact build or what your plans are for the future.  Or for that matter where you live, Climate wise.   Also, when asking a question on a board like this many people read it and go back to it for reference. Many others in the past have asked the same question. Many will in the future. I am just making points that you and others can use for consideration for your and their builds.

For instance, I am building a 450+/- hp motor for my 65' Coronet 500. I live in Florida where it is hot and muggy all summer. The motor going in NOW is a light weight, but I am going to set it up with a electric pump, fat lines and a regulator. It's probably over kill for this motor, but I have plans for a big stroker in the future. Also air conditioning. My car is fairly light and holds 4.10 gears RIGHT NOW..  Sure I could save some time and money right now, but I now what will be coming down the line later, so why do it 2 times when I can do it once.  Setting it up the way I am going to now will guarantee plenty of fuel all the time and will continuously be pumping and filtering and keeping fresh fuel all the way to the carb..

You can absolutely trust what Ron tells you. He doesn't plug for anyone unless he has used it or is close to someone he knows well that  has. The info I have given you is a step or two more toward hi horse, full blast runs with just about anything you want to throw at it and in most conditions..

Again, I am at Sea Level and don't need half of the stuff I am doing now. Some are at 4000 ft. above sea level and have shitty gas. (Vegas has shitty gas).....  Also 2300 ft. above sea level. Good place for a strong fuel system. Under 10.5 clicks at the track==== Better have a strong fuel system..  In a hot area that likes to cause problems with vapor lock.. You get the picture... 



This is of course my opinion.

[darrin75]

No maybe you took it the wrong way, I value all the opinions on the board, no problem at all.

[73ChargerSE]

What lines would a 400 '73 have? I'm guessing 3/8?

[Ghoste]

5/16.

[73ChargerSE]

Looks like all the sending units I'm finding for a Charger are 3/8.  I would think it would have 3/8 being a BB car.  Could be wrong.