5/16 to 3/8 fuel line

-
thanson_mopar

thanson_mopar

Well-Known Member
Joined
May 9, 2007
Messages
1,946
Reaction score
13
Location
Black Hills, South Dakota
i have my 360 (went from slant six to 360) in and broke in, theres a problem. It acts like theres not enough fuel past 4k rpm. i am assuming this is because i am still using 5/16 (slant six) fuel line? If thats the case what is all needed to switch over to 3/8. I already have 3/8 going from the feul pump to the carb. where or what company sells f3/8 feul line to go from the pump to the gas tank? also do i just have to put in a different sending unit into the tank? give me the lowdown
 
Tate, check the float level before you do anything.

Now, the sending unit will have to be changed out. Otherwise, the 3/8ths line everywhere else is still sucking through a 5/16 sized line and the problem, if that be it, will still exisit.

You can get 3/8's line from a number of sources. Finelines would be one, year one would be another but expensive spot.

Someone chime in on where to get 3/8's A body fuel line and sender.
 
I think Fine Lines will make just about whatever you want. But question first. What kind of RPM and/or 1/4 mile times are you running?

My (ex) 383 Bee still had the 5/16 line and I ran a mechanical pump. I'd turn 7000rpm (in 1 & 2) and would run 13.42@103.2 in the 1/4
 
You know guys, in my opinion for what it's worth, there is a lot of hype around changing to 3/8 fuel lines. I agree that if you're building a project going to 3/8 is a good idea cuss you're going to spend the money anyway. However, to switch from 5/16 to 3/8 is only required if you're running a high revver with a big assed carb. Remember a lot of B Body BB from the factory had 5/16 lines and ran just fine.
Before calling the fuel line size into question check first your float levels (as mentioned above) fuel pressure, fuel filters and general health of the carb if you haven't already. There is also a sock filter on the fuel tank pickup suction line that plugs with crud.

Terry
 
Yes, as well as many big block cars. I believe the 440 - 6 and HEMI got the 3/8 lines.
 
rumblefish360 said:
Yes, as well as many big block cars. I believe the 440 - 6 and HEMI got the 3/8 lines.
Click to expand...

I've had 3 440 B Bodies and 2 383 B Bodies over the years that all had factory 5/16 lines. Most of those got upgrated because of major engine mods like dual 4's and six packs.

terry
 
ic, well i guess mabe it is just the carb that is the issue, alls it is a carter AFB competition series, 625. Could timing also an issue. I had it timed to factory 74 360 specs, even though it is far away from factory
 
OH, I see, yep, you'll need to move away from stock specs.

I myself currently have my 318 to factory timing specs and it puffs smoke, unused gas. It'll need some advancement and carb tweaks.
For now, it was just set up to run so I can move it around when need be.
 
My (ex) Six Pack challenger had a 3/8 line with a 1/4 return, as well as the Six Pack runner I have for sale, and the other factory big block 69 runner I have.
 
Has anybody mentioned the fuel pump yet? Is it new?
 
rumblefish360 said:
OH, I see, yep, you'll need to move away from stock specs.

I myself currently have my 318 to factory timing specs and it puffs smoke, unused gas. It'll need some advancement and carb tweaks.
For now, it was just set up to run so I can move it around when need be.
Click to expand...

hmm, i guess im going to check float levels first seing as the feul line is not the issue. Is the fuel pump enough? it is just a factory replacment for a 74 360 hp
 
A factory replacement fuel pump should be good enough to put the car in the 13s. Like others said you don't need 3/8" fuel line unless you are putting out some serious power. If the pick up filter in the tank has never been changed that will severely restrict fuel flow.
 
With the 625 Carter carb on a 360 the 5/16 line should have enough flow capacity if no plugging or obstructions. If the tank is original there could be some rust and sludge clouding the intake screen.
 
I run about 19 degrees of advance at idle (as recommended by FBO). At a stock time setting it will hardly move itself out of the garage, so that might be your issue. By buddy had the same problem on his mid 70 Impala. His step dad acquired a 350 already put together from a friend of his. he called me saying it would backfire and die when in gear, but ran great at idle. When I checked it with the light it was something like 7 degrees. We slowly bumped it up to about 18 and it was running real nice after that.

I installed an electric pump at the tank, and decided to install 3/8 line while I was at it after reading info on FBO's website. The tank pickup is still stock, but that will get changed when I go to a new tank.
 
I`ve read that the "M code" cars came with the 3/8" pick-up and lines, but I haven`t owned one so couldn`t say with any authority. I believe the 5/16 line is adequate for cars deep into the 11`s. Like others have mentioned ,you may want to check the filter at the end of the sending unit and even the tubing itself for debris. If the car sat for any time then it`s possible the tubing is restricted with crud. Flushing with laquer thinner and pipe cleaners on a cordless drill will do a great job of cleaning the tubing on the sending unit.
 
You must log in or register to reply here.
-

Back
Top