Packard Forum Index » Post-War (1946-54)

I need to replace the original (mechanical pump) fuel line in my 2106. The car is also fitted with an electric pump that is plumbed via the Jim Dougherty method (dual lines to engine). I am considering a bit more elegant method as set out in Buck's method, but I am wondering about its effectiveness in preventing fuel to the crankcase.

There were brief comments here about the effectiveness of a check valve vs. duplicate lines.
https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=8202&viewmode=flat&order=ASC&type=&mode=0&start=0

I would like to hear more about the pros and cons of each method if you folks are so inclined.

Thanks,
Mark

Attach file:

---

  (22.30 KB)


  (30.37 KB)

I don't disagree with using the check valve but IMO, the only need for the check valve is if you are using a rotary vane pump. The mechanical usually can't pull thru those type pumps so the check valve circuit is necessary to let the mechanical pull around the pump. In that type circuit it would also be necessary to prevent the electric from taking the least resistance and just dumping gas back into a loop. The typical pulse type pump has valves functioning like the mechanical pump valves and has no issues with gas being pulled thru. That type is what most people use with the series setup.

As other have commented, in the series setup if there is a problem with the mechanical or its diaphragm, gas could go into the crankcase -- but that will be true with any electric pump going thru the mechanical. That is one advantage to the second method. Separate lines and if the mechanical pump valves are working properly, no gas can get into the crankcase. It is more complicated running the second line though.

Thanks Howard,
I am leaning toward the two-line method. I think I can clean things up a bit by running the two lines right next to one another, if that is possible. Since the electric line was an add-on, its line snakes through a different path and just looks rather sloppy. I am concerned about clearance with side by side lines where they go past the radiator support and where they snake around the shocks, but I think there is room. I'm thinking I should add some rubber tubing at strategic spots and perhaps some method of tying the lines together to avoid abrasion.

I think two lines in parallel would look very neat. Problem might be finding dual push in clips for the lines. Restoration Specialties has dual push in clips for 3/8 & 1/4 or 5/16 and 1/4 but no dual 5/16 so possibly a push in type like we use in our size is not available..

The 5/16 size seems to be an oddball. McMaster has a dual clip for 3/8 and with a piece of thin rubber hose as a spacer over the lines at each location might work and be presentable. Might also be able to use two single clamps back to back. I think the push in holes are all accessible so a nut and screw or if needed a sheet metal type bolt could be used to hold the clips.

Much as I dislike plastic, McMaster does have a dual plastic 5/16 clamp on box like thing that might work in a few strategic spots to keep lines together and vibration down-- the area under the radiator and where it is suspended under the doors for example.

Getting around the shock will be tight but I think doable. Will be a lot easier if you use the cupronickel tubing instead of the original steel. That is what I wound up using and was able to bend most by hand.

I finally found some 5/16 copper/nickel up here. Wow, what a difference from steel. Also, I discovered that if you are going to double flare, get the tool by Rigid and forget the auto parts store version.

I was thinking of using the original style clips for one line and then attaching the second line right next to, or above, as required for clearance in tight spots. Maybe something better than the cable ties that it came with. Small band clamps might work where they don't show, or perhaps I can find a separate clip or some less modern looking clamp that would join two 5/16 lines.

Thanks Howard,
Mark

I would use a pair of Adel clamps (aviation term, just google "cushioned clamp") on a single screw or bolt at each clamping location. Better and cleaner than the cable ties and won't chafe the lines.

In my car I am going to install an electric pump but just a pulse type in series with the mechanical pump, I hope that the only time I'll need it is for priming the system after long layoffs. After that the mechanical pump should be enough. So, no extra lines for me so far.