OEM fuel-line size
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- GTX (RS)
- Posts: 293
- Joined: Sat Oct 28, 2006 12:21 pm
- My Cars: 1973 Road Runner 440/4 speed
- Location: 92508
OEM fuel-line size
Okay, so as I was cleaning up the fuel tank (bad gas) and replacing all soft lines, it occurred to me that my car originally had a 400 in it, and not the 440 that's currently in it. Is there a difference in fuel-line size between the two? I've always heard 440/Hemi cars have 3/8" fuel lines and all else has 5/16". I presume that includes the pick-up in the tank, the hard lines that run across the vehicle, the fuel pump, all soft lines, etc.
I'm not sure what my 400 car had stock, anyone know?
I'm not sure what my 400 car had stock, anyone know?
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- 72RoadRunnerGTX
- GTX (RS)
- Posts: 594
- Joined: Wed Dec 27, 2006 6:44 pm
- My Cars: 1972 Road Runner/GTX
1972 Satellite Sebring
1972 Satellite Sebring(big block parts car) - Location: Seattle, Washington
If the car had 3/8†fuel lines, then it would have had tank sending unit with a 3/8†pickup tube as well. The repo sending units available for these cars today come with either a 5/16†or 3/8†pickups. 3/8†Fittings and hoses would have been used to the pump. Pump to carb/carbs feed lines typically would have been 5/16â€.

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- GTX (RS)
- Posts: 293
- Joined: Sat Oct 28, 2006 12:21 pm
- My Cars: 1973 Road Runner 440/4 speed
- Location: 92508
Remind me to add "replace fuel lines with 3/8-inch" to my to-do list sometime. Darn... But gotta feed baby since she's a 440 with a Holley Street Dominator and a four speed and baby's hungry...71440 gtx wrote:its 5/16 for 318 340 383 400 360
3/8 for 440 4bbl 4406bbl 426 hemi and 1/4 return line![]()
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I had a 71 runner with a transplanted 440 for 12 years, originally 383 car, it was built to run 12 sec quarters, still had the original small lines and never any problems. You'll probably be fine with what's there now if it's in good condition.
AKA Butterscotch71....the road runner nest is out to win you over this year!
- mopar71
- GTX (RS)
- Posts: 1108
- Joined: Sun Dec 14, 2003 11:55 pm
- My Cars: 1971 roadrunner
- Location: Milford,PA
Patrick, any problems with that Holley Street Dominator? Thats what I was going to put on mine.patrick wrote:Remind me to add "replace fuel lines with 3/8-inch" to my to-do list sometime. Darn... But gotta feed baby since she's a 440 with a Holley Street Dominator and a four speed and baby's hungry...71440 gtx wrote:its 5/16 for 318 340 383 400 360
3/8 for 440 4bbl 4406bbl 426 hemi and 1/4 return line![]()

MOPAR (Move Over Plymouth Approching Rapidly)
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- GTX (RS)
- Posts: 293
- Joined: Sat Oct 28, 2006 12:21 pm
- My Cars: 1973 Road Runner 440/4 speed
- Location: 92508
I've acquired the part(s), but the actual install is pending after I run gas from the newly cleaned tank for a little bit (I figure since I have a new carb/intake, might as well (potentially) damage the old, crappy one).mopar71 wrote:Patrick, any problems with that Holley Street Dominator? Thats what I was going to put on mine.patrick wrote:Remind me to add "replace fuel lines with 3/8-inch" to my to-do list sometime. Darn... But gotta feed baby since she's a 440 with a Holley Street Dominator and a four speed and baby's hungry...71440 gtx wrote:its 5/16 for 318 340 383 400 360
3/8 for 440 4bbl 4406bbl 426 hemi and 1/4 return line![]()
Is yours a four speed? I'm hoping, in my case, this helps to make up for the fact it's a single plane.
What is the primary duty/intent of your car? What kind of carb will you be running? Cam and heads, for that matter? Too many variables. Mine is strictly a street car. Carb is a 750cc Edelbrock (brand new) because I got it for under $200 on E-bay; in reality, I know Edelbrock measures their flow rates higher than Holley so I know I should probably have an 800cc on there. For some reason, I don't like Holleys, which I think is just brainwashing caused by my BFF while we were growing up ("Carter is best" mentality). Whether it's true or not is arguable, but just something that stuck with me all these years.
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