Fuel Line Size on my 69 GTX

[Jack Luckhowec]

Question for the Mopar gurus.
I just pulled the tank from my very original 69 GTX, 440-4, 4 speed. I noticed that the fuel line on the sending unit is 3/8", while the line running to the front is only 5/16". both are for sure original. Is that normal?? Seem strange to have a mis-match.

 

[moparedtn]

Interesting. Should be 3/8" all the way...

 

[68Moparmaniac]

Vapor and return lines usually 1/4 or 5/16 if i recall. Your main fuel line for the BB should be 3/8.

 

[turbine68rt]

No, not unusual. I just went through this on mine. I had the exact same scenario on my untouched '68 R/T. When I replaced the fuel lines I changed it to 3/8 but it definitely came with 5/16 from day 1.

 

[origcharger]

Curious how do you know the sending unit is original?

 

[turbine68rt]

I also thought it was a bit unusual to only find new sending units in 3/8x1/4 and the 5/16 didn't have the 1/4 return. Fortunately my original still works fine. New pickup sock and it's good to go.

 

[R/T Boy 67]

68 and 69 440 cars had 5/16 fuel lines and 3/8 sending units. They went to 3/8 fuel line in 70. They used a return line for 440 and hemi cars starting in 68, so they just used the same sending unit for both.

 

[JimCoronette]

Both lines should run to the front. 3/8" supply, 1/4" vent/return.

Oh, and the ground clip is missing, does your fuel gauge work?

 

[Jack Luckhowec]

Curious how do you know the sending unit is original?

For sure its the original sending unit; look at the pic; even the original hose clamp was left behind!!

 

[Jack Luckhowec]

Both lines should run to the front. 3/8" supply, 1/4" vent/return.

Oh, and the ground clip is missing, does your fuel gauge work?

Yup, the fuel gauge worked perfectly!!

 

[Jack Luckhowec]

68 and 69 440 cars had 5/16 fuel lines and 3/8 sending units. They went to 3/8 fuel line in 70. They used a return line for 440 and hemi cars starting in 68, so they just used the same sending unit for both.

That makes sense and explains why the car has 5/16 fuel line and 1/4 vapor line.
Thanks everybody who commented to clear up this mystery.

 

[Dipstick]

View attachment 997988 View attachment 997987

68 and 69 440 cars had 5/16 fuel lines and 3/8 sending units. They went to 3/8 fuel line in 70.

The factory parts book disagrees, from the '70-'71 book. Only shows 5/16" hard tube.

 

[BLK 68 R/T]

My 68 gtx, 4 speed car also had a 5/16 main fuel line from the factory.

 

[Jack Luckhowec]

My 68 gtx, 4 speed car also had a 5/16 main fuel line from the factory.

Did it allso have a 3/8 sending unit??

 

[BLK 68 R/T]

Did it allso have a 3/8 sending unit??

I honestly don’t remember what the sending unit was, don’t think I ever had it out or dropped the tank for anything. Just remember the engine bay hookup had the 5/16 line coming in from the tank.

 

[72RoadrunnerGTX]

View attachment 997988 View attachment 997987

The factory parts book disagrees, from the '70-'71 book. Only shows 5/16" hard tube.
View attachment 997989

“AR-as required”, that’s bulk 25’ roll tubing, does not specify any application. The statement that beginning with ’70, 440 applications came with 3/8” hard fuel line is correct.

 

[Should be playing golf]

I have a 69 GTX 440 4-speed, Dana car and have had the gas tank out twice, put in a new tank, two new sending units, Checked all wiring 15 times, checked the gauge, voltage limiter, tried numerous grounds, etc....Sending units work great hooked up out of the car, reinstalled everything...put 8 gal. of the sucked out gas back in...measured half full, fantastic! filled up the tank, still half full...WTF is going on? I got a hernia and went through two creapers in the process.
Has anyone ever built a bench tank mock-up to mount a sending unit to, to see what the heck is going on in there?

 

[gtx6970]

Ive had 2 previous 1969 440 GTXs equipped with a 3/8" sender and 5/16" main line. Both were St Louis built cars

 

[1967coronet]

Mopar replacement and after market fuel senders should not work correctly. If you have one that does there is a problem and it should be removed.

 

[Should be playing golf]

Just wondering about using a mock-up to sort things out. Mount the sending unit at the proper angle in a cardboard box made to the exact dimensions as the fuel tank and hook it up...see what happens. leave one side open to move the sending unit up and down.