Space Wagon Fuel System Upgrade

[drdano]

I'm starting the process of upgrading my fuel system in my '62 wagon.  My first update will be to see if replacing the 5/16" line from my pickup in the tank to the M6905 fuel pump will free up enough restriction to get rid of the dead spot above 4000rpm in 1-3 gears while on a quater-mile run. 

So tonight I got the pickup removed from the tank.  I had already contacted RobbMc and there didn't seem to be a real straight-forward way to have him modify this pickup, so I'm taking a swing at doing it myself.  I got some 1/2" steel fuel line from the local hydraulic supply house and we'll see how this goes.  Plan is to go 1/2" pickup steel lines to -8 AN to the pump, -8 AN to the filter after pump, -6 AN (maybe just do -8..what the hell) to the carb.

Since I'm using a mechanical pump, I'd like to use a 1/2" filter sock.  Yes yes, I know they're restrictive potentially and you have to pull the sender to service them...but is there one for 1/2" I'd be able to get locally or via Summit when I order the rest of my fittings?

Also, what are you guys using to connect hard line to AN fittings?  There are hard-line to AN couplers I've seen, but the descriptions all says to "used to connect to aluminum fuel line"...which I am not going to be doing.  I could bell the tube on the outside of the pickup and slide the braided hose over with a worm hose clamp...but that is a pain in the arse to disconnect each time.

[jayb]

What I've usually done is welded a steel AN fitting onto the steel line, and connected the AN line from there.  You can also use a hard line to 45 degree steel flare fitting; that way the tube and the fitting are the same material, and you can tighten them together without any worries.  The flare fitting could have, for example, a 3/8" male pipe end, so then you could use a pipe fitting to adapt to AN.

[mlcraven]

X2 on Jay's response re connecting hard line to AN fittings with 45 degree steel flares.

Sorry this doesn't answer the sock question, but there have been several on-line debates on gearhead sites about the need for filter socks, to my thinking never with certain resolution one way or the other.  When I refurbished the Cyclone fuel system there was no filter sock -- either ditched by a previous owner or simply fell apart (although I didn't see any bits of such a thing come out of the tank when I fully emptied it).  My understanding is that the big thing a sock prevents getting into the fuel system is rust particulate, in the old days mainly due to cheapskates running their tanks at less than a quarter full (with resultant cold climate condensation).  Maybe nowadays due to crappier fuel or fuel with ethanol?

I ran the half inch fuel system in the bracket car without a sock but was always careful to keep the tank pressed full.  Will be interesting to see what the inside of the tank is like after 5+ years in storage -- I'm thinking the Stabil will be well beyond its best before date.

[drdano]

Pulled the fuel pump off and pulled it apart.  I remember enlarging the internal passages to 5/16".  Upgrading the 1/4"NPT fittings to 3/8" and enlarging the internals a tad further as well to get at least 3/8" diameter flow through it.  There will be a step down from the -8AN supply line from the tank to the inlet of the pump, but it will be way better than it was.  On the old setup there was a 1/4" NPT inlet, with a reducer to a 1/4" fuel line barb.  Ouch!

On coupling the new 1/2" pickup, I can definitely tig weld an AN fitting on the end.  I dont have a 37 degree flaring tool, but the local hydraulic shop can probably do it for free if I decide to run an AN tube nut and sleeve to connect that up and buy them from their shop.  Choices choices...

One question, the new pickup line I got is regular vanilla steel tube.  The current pickup assembly looks like stainless?  Any reason other than rust I should drop what I'm doing and go with stainless for the new pickup tube?  Theres no rust in the tank or anywhere on the pickup assembly.

[mlcraven]

Stainless looks good but is a royal PITA to work without the right tools -- I say stick with the steel.

[drdano]

Here is the modified pump.  I figure it would be a fun experiment to see what would happen if I modify the inlet and outlet diameters so that I could at least hang -8 AN hoses without it having to step down to what turned out to be barely 1/4" and I recall enlarging already to 5/16" before I ever ran the pump. 

The inlet side was drilled out for 3/8" NPT so I can go direct to -8 AN braided PTFE line.  When I got to 1/2" on the drill the housing broke through, so I had to sleeve the lower housing with a piece of 1/2" thin wall steel tubing and epoxied that in place.



Outlet side half of the pump was drilled to 9/16", tapped to 3/8" NPT.  Pretty huge difference from the barely 1/4" outlet hole diameter here.



Completed unit with new 3/8" NPT threads and all the internals cleaned up to be as restriction free as possible.  I even took my micro electronics diamond files and smoothed out the casting holes where the flapper valves are.  Most were ok, but some were pretty hideous with casting flash.

[jayb]

Nice job on that!  Should make a significant improvement in fuel flow...

[machoneman]

Nice work! Have thought about doing something similar but really don't need that much flow. Still, I wonder why so many fuel pumps, even performance pumps, have that severely necked-down  inlet that kinda' kills the whole idea of large diameter fuel lines. 

[drdano]

I'm not sure either.  I could have easily redrilled and retapped the inlet and outlet only to 3/8NPT so you can go direct to -8AN...however, right behind that fitting would be a reduction to 1/4" diameter defeating the whole purpose.  I have no idea what this will do pressure wise, I'm hoping it says the same but the flow increases.  My gut tells me it should since I'm not messing with the diaphragm spring.

Barry R and others claim that this pump can adequately feed a very healthy FE on the other forum.  I know my factory 5/16" hard line to the tank was hurting me, perhaps that alone was the issue.  A true nerd would have made one change at a time and then re-ran on the road to look at the data.  I just figured I'd do it all at once.

Oh, and I forgot to mention, I also got two new filters from RobbMc.  One 100 micron pump pre-filter that I'll install in front of the pump, and another 40 micron I'll install between the pump and carb.  Both are rated for 150gph, which should be adequate.

[bluef100fe]

I'm running the carter m6905 pump on my truck with the stock sending unit and a new 3/8 stainless fuel line to the pump and it seems to keep up fine... I think I will be making some modifications to the trucks fuel system soon though. I will probably work on the pumping housing similar to what you have done but I will probably build a sump on my stock tank and run 1/2 inch line to the pump from there... A -10 from pump to fuel filter then a -8 line to each float bowl from the filter... I'm not land speed racing though.. I only need to feed the carb at wide open for 12 seconds or less at a time... I think a large volume of fuel on the pressure side of the pump helps a lot on when drag racing with a smaller capacity pump... Anyway nice work...

[drdano]

but I will probably build a sump on my stock tank and run 1/2 inch line to the pump from there...

Funny you should mention a sump.  So, on Saturday I managed to get down to one of my favorite boneyards to see if I could find a tank that is in better shape than the one currently under the car.  The current one is smashed in pretty bad, so bad in fact that the float can't travel to it's lowest position and never goes below 1/8 tank on the gauge up front.  I had seen a fuel tank pulled from a wagon (which is different than a regular galaxie tank) sitting in the back of a wagon that I pulled the rear quarter glass from last year.  Low and behold it was still there.  I not only didn't have to drain the tank, pull it, the yard guy was moving a truck and took it 1/4 mile back to the office for me and carried it to my car.  When I got home, I got a good look inside and it's nearly spotless for a 50+ year old tank!  $60 well spent!





So, I'm now templating up a small "sump" to hang off the rear of this tank with dual 3/8" NPT fittings.  I have the fittings and sheet metal on hand, so I'll do that rather than up to 1/2" NPT.  I figure if I'm going to need dual -10AN feeds someday I'll probably need a real fuel cell.   

[drdano]

Mockup of the mini-sump tonight.  I can't put a full 3" deep sump on the tank since the car sits so low.  I'm a bit paranoid of a big roller on the interstate bottoming the rear end out and smashing the tank in, so this is more of a mount for the NPT fittings than a sump at only 1" deep.

[drdano]

Got some steel mocked up with a 1/4" flange.  Not too shabby considering my only formal body tools are crap HF hammer set and an offshore knockoff bench vise as an anvil...



Edge.  Felt nice to get some tig welding in again.  Very therapeutic for the soul.



3/8 NPT vs 1/2" NPT both with a -8AN fitting.  Went with the 3/8.

[drdano]

Final trimming and ready to attach to the tank.

[drdano]

Mini sump finally finished tig welded in place.  Can now have the tank blasted, pressure tested and powder coated.