whats the right fuel sending unit - 5/16 or 3/8 " pick up ?

Fuselage Years

  1. marko

    marko Active Member FCBO Gold Member

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    i need to replace my 70 300's fuel sending unit - whats the right one -
    ive found 2 on ebay -
    3/8 or 5/16 pickup

    tx
    mark
     
  2. Sixpactogo

    Sixpactogo Member

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    Do you have a 1/4" return line going back to the tank? From my experience, the 383 cars had the 5/16 pickup with no return. Most 440 cars use the 3/8 pickup and had a 1/4" return. At least in the B body cars, not sure about the C's
     
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  3. 413

    413 Active Member

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    Measure your hard line from front to back. Sender should be the same size. You can use an open end wrench, it will be slightly loose for the correct size.
     
    Last edited: Sep 25, 2019
  4. marko

    marko Active Member FCBO Gold Member

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    my car is in storage at the moment so i cant measure it for prob quite a while.....
    somebody told me that because my car is a 440 TNT they thought it would have the larger pickup but i havent heard anything else to confirm that
     
  5. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    Hemi cars and 440- 6pack are the only ones that came with 3/8s line. Not a bad upgrade but unless you are running it to 6500 to it is probably not needed.
     
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  6. 413

    413 Active Member

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    1967 GTX and R/T coronet with 440 4bbl engine and the 4 speed manual come with 3/8” fuel lines and senders. I’ve owned 2 of them. Still have one.

    1970 440 4 bbl B-bodies with either trans comes with 3/8” supply line, 1/4” return line and a fuel vapor separator. The sending unit has the same size lines. I’ve owned 3 of them, still have one. That’s how they made them.

    So this 1970 300 Hurst with the same U code 440 4 bbl engine may just be right in there at 3/8” with the B-bodies. Not sure about C-bodies so check your fuel line size on the body.
     
    Last edited: Sep 25, 2019
  7. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    Pretty sure the only C-Body that came with 3/8" line in '70 was the 6BBL Fury GT. I have a 440 high performance in the the '70 police cruiser and that is a 5/16". The 6BBL was a possible option on the cruisers as well but they are very rare if any still exist. As noted, if in doubt, measure the steel fuel line.

    Dave
     
  8. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    Thank God for the ignore button, I don't have to be subjected to such stupidity.
    Listen to the Brain trust he knows everything.
     
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  9. Trace 300 Hurst

    Trace 300 Hurst Well-Known Member

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    My 1970 300 Hurst is ALL 5/16, tank to carb. I replaced the entire system (tossing away the PO's lovely rubber hose that ran from the tank to fuel pump to carb! :BangHead: ) using Inline Tube's products.
     
  10. 413

    413 Active Member

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    Do you know what the factory put on the 300 Hurst before the PO added the rubber hose?
    Who offended you here?
     
  11. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    When in doubt, go to the parts book.

    The part number for a '70 C-Body (that isn't a station wagon) tank sender is... Drum roll... 3420849 and it is the only part number listed.

    So... that means that the same sender is used for all the 70 C-Bodies and since we have people here saying that 5/16 was the fuel line size was used.... Well, the obvious and correct choice is 5/16".

    The sender in my '70 300 is 5/16. I know, I've replaced it.

    Section 14-72-0
    Tank Gauge.jpg
     
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  12. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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  13. polarus

    polarus Senior Member

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    I agree that 5/16 is the standard as far as my 72 parts book states. Police cars had an option for a 3/8 fuel line and pick up, my U code Polara has the 5/16 line but my parts car a T code has the optional 3/8 line and pick up.
     
  14. Trace 300 Hurst

    Trace 300 Hurst Well-Known Member

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    Yes. 5/16ths, no vapor separator return line. That is what the tank nipple is, and both ends of the fuel pump, plus I researched it, etc.

    An OEM 440 in a 4400 lb car with a 3:23 rear and a shift point of 5200 simply can't use all the gas a properly-operating 5/16 system can provide. which is why Chrysler sized it that way. A 1970 Highway Patrol car that might have to run at 130 mph for 20 minutes on a wide open highway to catch a bad guy might call for the use of bigger line, especially if consideration is given for partially clogged line or fuel filter. Cop brakes, cop tires, cop shocks, cop fuel system. But a regular Andy Griffith patrol car wouldn't need such an upgrade.

    A hemicuda with a 4:10 gear, 4 speed, and 6500+ revs? Yeah, that's another story. 3/8ths pipe and that fancy hemi pump are needed.
     
    Last edited: Sep 26, 2019
  15. Sixpactogo

    Sixpactogo Member

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    I have no idea what was or was not used for fuel lines in C bodies. My experience lies with the B body cars. Namely Chargers. Back in 1968 I bought a new Charger R/T 4 speed car. My brother had a 383 4 speed car that had trouble with vapor locking on hot days. One of the guys at the track said to wrap the fuel line with dry ice. We were both young and dumb back in those days but when we decided to look into why his car was vapor locking and mine didn't, we noticed that my car had the 3/8" line with vapor canister and a 1/4" return line to the tank. His had the single 5/16" line. We robbed the lines, canister and sender from a wrecked Charger R/T and put it on his car. It never vapor locked again. No idea why the R/T got the return line and the 383 didn't. Since the R/T only had 40 hp more than the 383, we thought since my car had 3.55 gears and his had 3.23 gears maybe one or both differences were the reason for the upgrade. Chrysler must have known about the issue or they would not have added the return line. Since the cop cars got upgraded performance, suspensions, and brakes, I would have thought they would have got the upgraded fuel lines too but what the hell do I know?
     
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  16. 413

    413 Active Member

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    That is how they built the 440 4 speed cars. I tried to tell ya but some guy had question it.

    Both of those reasons were why they did it, gears and cubic inches. You see how far ahead the 440 car was over a 383 in a race? That’s burning fuel to do that so they upgraded the system. They already had it from the hemi engine, they just shared it around a bit more.
     
    Last edited: Sep 27, 2019
  17. Dobalovr

    Dobalovr Being on the Cbody diet SUCKS! FCBO Gold Member

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    Sorry @marko I was onboard and didn’t catch your post I could have told you it was the 5/16” version. How’s it looking otherwise?
     
  18. 67Monaco

    67Monaco Old Man with a Hat

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    Who dat?
     
  19. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    I don't know I can't see him. Such dumb statements I chose to Iggy.
    Probably a post that says don't do that with no explain.
     
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  20. 67Monaco

    67Monaco Old Man with a Hat

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    At least I'm not the only one had that thought. Those posts have been bugging me for some time now and I thought it was just me.