1970 Deville fuel line size

[Bill Balkie 24172]

Hello 69 / 70 Cadillac people .  I have a question . The  steel fuel line  coming from the fuel pump to the   Carbureter what size line should it be ? My car has a 1/4 steel line from the pump to the carbureter.  The fitting on the fuel pump is a 1/4 " inverted  flare .   All the new fuel pump that I see have a 3/8 inverted flare inlet fitting . �� Thank you very much

    Bill

[The Tassie Devil(le)]

Sounds like your new pump is not an OEM type, but all is not lost.

What you need is a flare nut with the correct thread, and the correct hole for the tubing.

This is done a lot with Brakes, so that people cannot accidentally put the tubing in the wrong place.

The correct line size is 5/16" OD.

Bruce.

[Bill Balkie 24172]

Sounds like your new pump is not an OEM type, but all is not lost.

What you need is a flare nut with the correct thread, and the correct hole for the tubing.

This is done a lot with Brakes, so that people cannot accidentally put the tubing in the wrong place.

The correct line size is 5/16" OD.

Bruce. Thank you Bruce ,  5/16 seams more like it . How did my car end up with a 1/4 line and it is all Pre-bent and fits perfectly . The inlet to the carb is 1/4 and from the pump 1/4 .  It's puzzling to me

    Thank you

[TJ Hopland]

Since the blocks were the same through 81 its likely that the current parts people just figure that 3/8 covers more years than the 5/16 did that its close enough to say fits all.  The earlier 70's pumps had a pretty large can under the pump that had a big nut for the outlet that held the filter.  Later 70's had a largeish can still but filter was in the carb inlet.  I think the 80/81 looked like any other mechanical pump without the large can which I think is also what the first few years looked like too but with different size fittings.   

[Bill Balkie 24172]

Since the blocks were the same through 81 its likely that the current parts people just figure that 3/8 covers more years than the 5/16 did that its close enough to say fits all.  The earlier 70's pumps had a pretty large can under the pump that had a big nut for the outlet that held the filter.  Later 70's had a largeish can still but filter was in the carb inlet.  I think the 80/81 looked like any other mechanical pump without the large can which I think is also what the first few years looked like too but with different size fittings.   

with all that being said . I am trying to find a pump that has a 5/16 inverted flair outlet with no success. If replace my fuel line to 3/8 do you think that would be Ok having a 3/8 line feeding the carbureter?
I would also have to change the inlet on the Carbureter to 3/8 . I am still going to find a fuel pump that has a 5/16 outlet but I have been striking out so far . Unless I could find a replacement nut for the new pump that has a 5/16 outlet.   Thank you for you help.
    Bill

[TJ Hopland]

I checked a bunch of places and its really depressing that even the 'specialty' vendors are just passing off the 71-76 chain store listing as correct for 68-81.  Also depressing that so many vendors look to be just buying them on line from the major vendors and marking up the heck out of them.  If they are making the part or doing extensive quality checks that is one thing but it sure looks to me like they are just reselling the same crap anyone can buy. 

I have been told the The Oldsmobile pumps are mostly the same and will bolt up of you change the arm. A quick look and it looks like the Olds with AC the pressure line comes off at an angle but maybe that would be good if you have to adapt the line size?  I also don't know how much of a pain it would be to change the arm.  The pivot pin is staked in so it would take some grinding and pressing out then would have to be staked again or I think swedged is the machining term. 

[klinebau]

with all that being said . I am trying to find a pump that has a 5/16 inverted flair outlet with no success. If replace my fuel line to 3/8 do you think that would be Ok having a 3/8 line feeding the carbureter?
I would also have to change the inlet on the Carbureter to 3/8 . I am still going to find a fuel pump that has a 5/16 outlet but I have been striking out so far . Unless I could find a replacement nut for the new pump that has a 5/16 outlet.   Thank you for you help.
    Bill

If you already have a pump with the 5/16 fitting, you can swap it over to the new pump.  You can also change the line to 3/8 with no problem.  The 3/8 fittings for the carburetor are readily available.  As long as the fuel pressure to the carburetor remains roughly the same, there are no issues with a 3/8 fuel line.  A third option is to get a flare adapter (5/16 female to 3/8 male), but you might need to bend the fuel line a bit to get it to fit.

[TJ Hopland]

I'm assuming one issue with fitting the later pump is the size of the canister below the cast part.  The early 70's pump canister is like 4 or 5 inches tall vs what an inch or two on the original?  Or was 70 the big can and just 68? the short one?   Which year had the inline filter that is impossible to find today?

If the 70 has the short can that moves all the connections down at least 3 inches which is more than you are going to easily be able to tweak a steel line.   The big can style the outlet points down so the carb line has like a J loop in it to bend around and point up to the pump.

[klinebau]

The '70 does not have the external in-line fuel filter.  It may just be 68.  The standard replacement fuel pump that everyone sells fits fine with the exception of the flare fitting for the fuel line.  All of the new replacement pumps ship with the 3/8 fitting and the 70 requires a 5/16.

[Bill Balkie 24172]

If I could find a reducer fitting from 3/8 inverted flair to 5/16 inverted flair that would solve the problem .

[klinebau]

I believe this is what you need, although I was able to find at my local O'Reillys.  Keep in mind that you _will_ need to bend your hard line to make this fit.  I originally used this on the carburetor end and had to tweak the line somewhat.  With the J-bend on the fuel pump side, you will need to make a more severe bend.

https://www.summitracing.com/parts/ear-00120erl

[Bill Balkie 24172]

Clinebau ,
     Thank you so much , just ordered it .
    Thanks Again ,
         Bill

[Bill Balkie 24172]

Hello to every one , I have to apologize I misrepresented my fuel line on my car the steel fuel line is 5/16 looking at it closely I thought it was a quarter but after putting the Vernier micrometer on it it is 5/16 makes me feel better. And I was so happy to track down that 3/8 to 5/16 inverted flare reducer thanks to Klinebau.

[Cape Cod Fleetwood]

NONE of the new replacement fuel pumps for 1970 have the inlet for the fuel filter under the pump. Hide an in-line somewhere. And if someone knows of a new replacement pump that DOES have that inlet for the filter under the pump, lettuce know please.

[TJ Hopland]

So A 70 has the tall canister with the internal filter?  Looks like this? Only catch is its supposed to have a 5/16 for the outlet?   This is what I would have called the 71-76 which had the filter, 3/8 flare outlet, 3/8 barb inlet, 1/4 barb vent.   77-79 and I imagine 80 was similar and same lines sizes but didn't have the big nut holding the filter.  Filter was relocated so that was just a square block with the flare fitting.  Did the 70 also have a 5/16 inlet to match the 5/16 outlet?

[Joe G 12138]

            A few years ago I had to thin out my spare parts before a big move, and sold off a bunch of NOS AC fuel pumps, thus had to look up a lot of numbers to identify them. Although not real fresh in my mind, it seems I had two types for 1969. Air conditioned cars used 3/8 fittings, non-air used 5/16. 1970 could be the same situation?  There would be no harm in using an adapter fitting on one end and calling it a day.       Joe Gibeault

[TJ Hopland]

AC cars also had the 3rd line by this time period so that would have been another difference.  I could see the possible logic in increasing the line size if there was ac and the return line since some of the fuel would be getting sent back to the tank maybe they were worried there may not be enough volume left for the engine.

No one can confirm or deny that the one in the photo looks correct for a 70 except perhaps the thread size?

[Cape Cod Fleetwood]

TJ you're not going to find a 'new' pump from RockAuto, O'Reilly's, AutoZone, NAPA - ANYONE that takes the internal filter in the pump. That's a NOS, NORS part only. As someone said the thread size will be dictated by whether or not you have AC, the pumps (when they were available) specified AC or not. And these pumps are becoming unobtanium. When Michael changed my original pump to a 'new' one (wish I had that day back) he had to do some sorcery with the fuel line going to pump that was related to the size of the pump as I remember. And to add more misery, the NOS/NORS pumps are crimped so Gould can't rebuild them. There is a 'screen' where the filter should be, similar to at the fuel intake on the carb. You may have read I recently tried to add an in-line filter to The Ark, the car pitched a fit then refused to start. Be grateful you found a pump, make it work.

[TJ Hopland]

I'm still not clear what a 70 w/AC is supposed to have.   Is it like the photo?  But with 5/16 flare, 5/16 barb, and  1/4 barb?

[klinebau]

1970 fuel pump with AC -

• Inlet barb:  5/16"
• Return barb:  1/4"
• Outlet thread:  1/2"-20 inverted flare (5/16" line)

1970 fuel pump without AC (same as above with no return barb) -

• Inlet barb:  5/16"
• Outlet thread:  1/2"-20 inverted flare (5/16" line)

The fuel filter fits inside the pump behind the outlet fitting.  There is a kind of spring that holds the filter tight against the outlet fitting.