Using unions instead of fuel line?

I'm trying to keep my fuel setup compact.

What I've got is basically this:

Note my awesome Weldon Racing pump - continual duty, no fuel controller needed, and flows up to 1600hp, muahahaha.



What I'm wondering is if you look at the bottom you have a 90* female/female on the filter and pump joined by a union. I will also be making the same connection at the top (female/female 90* with a union joining pump and post-pump filter).

I'm wondering if this is okay - will vibration cause these connections to loosen? I'd rather not use hose ends here because I'd have to signifigantly increase the size of the bracket. Here I can keep everything tight and compact.

This is not the answer to your question, but in line with your own thinking what I am doing with connections like that is simply bending (with suitable tube bending tool eg Ridgid 408) a piece of seamless stainless steel tubing and flaring it at both ends using 37-degree tube nuts and tube sleeves (eg Aeroquip FBM3676 and 3672 for -8 line). Cheap and simple. If the pump or filter on either end is solidly mounted there should be no relative motion between the two ends of the tube, and thus no more of a loosening problem than if you used hose and hose ends. I try to use hose only between two locations that can move relative to each other.

The way you have put thsi together this is compact and nicely done. I see no reason for any concerns in relation to the design. The one thing to remember is that quality fittings yield reliability.

The cheep stuff like Russel fittings or the no name brands are very weak, especially the bent tube fittiings. I have broken both Russel and Jegs brand AN- 6 tube fittings just trying to put them onto a hose. I make all my own hoses and have done a LOT of them so I am careful and fairly certain that it's not ham handedness on my part. The good stuff is strong and the cheap stuff isn't. Who would have thought.........?

I only use Earls, or Aeroquipe for these type of bent tube fittings and have never had a failure yet.

Good point Howard. Alex, heed the advice and you won't go wrong!

As long as the two units are bolted to the same panel or in some other way to keep any movement of one in sync with the other - you should be fine.. I only use Aeroquip (and you know that) as they are far better made than the others. I've also used an almost identical approach as this with a couple of other cars I've built..

If you look at the bottom of the picture below, you'll see an Oberg filter just prior to the external spin-on filter mount. They are coupled with a -12 double-female union..

Howard Jones said:

The way you have put thsi together this is compact and nicely done. I see no reason for any concerns in relation to the design. The one thing to remember is that quality fittings yield reliability.

The cheep stuff like Russel fittings or the no name brands are very weak, especially the bent tube fittiings. I have broken both Russel and Jegs brand AN- 6 tube fittings just trying to put them onto a hose. I make all my own hoses and have done a LOT of them so I am careful and fairly certain that it's not ham handedness on my part. The good stuff is strong and the cheap stuff isn't. Who would have thought.........?

I only use Earls, or Aeroquipe for these type of bent tube fittings and have never had a failure yet.

Click to expand...

I totally agree. I only use Aeroqiup. For straight fittings I use Earls because I can't get a straight aeroquip onto braided hose for the life of me. I usually end up causing damage to the hose. I don't know why, but straights (atleast -10) are impossible for me to do. But the Earls are a piece of cake. Weird


Btw, I've broken 1 aeroquip fitting. But as you guys know, I can break almost anything, so that's not saying much.

Alex, the strongman! He does the "twister" just for practice...

Kidding you Alex!

Okay, finished, there's another thousand, lol





The little 40 micron filter at the end is my filter for my vent line - I couldn't sell him so I figured okay, he's my new vent filter, lol!

Definately going to need a solid splash shield (already knew this - on the other side my battery is infront of the tire :/ ), but I'm 1100000% happier keeping the fuel out of the rear cockpit. Sorry, but after having 3 leaking fuel pumps (Aeromotive) that spewed 12oz of fuel on cold starts, I have nightmares about what would happen if it leaked in the rear like that.

Out of curiousity, does anybody see anything wrong with the above setup relating to the flow of it? I got into an argument on another forum with somebody who thought it will kill my flow because the flow is like a pretzel.

I don't think so, but it did leave me doubting myself. I'd agree that straight shoots of line are always best, but I want to keep the fuel pumps/filters out of the rear cockpit area so that doesn't leave me many options.

Fyi, mounting the pump vertically is acceptable - it pulls > 26'' mercury and can be mounted horizontally or vertically, above or below the fuel cell.

Very neat Alex, it should work well with that pump too!

EFNFAST said:

...somebody who thought it will kill my flow because the flow is like a pretzel.

Click to expand...

"Kill" your flow???? I'm curious as to what your friend on the other forum thinks you should do instead. Is the predicted death of flow backed up by any numbers or sound analysis? Sure in principle you could mount the pump horizontally so the whole thing is a "U" instead of an "S". But who thinks that two extra elbows is going to matter and why?

It's a mustang forum - you know the type where females sign up and the first 10 posts are 'post n00dz' :lol:

But comments always make me question myself. I didn't think having 1-2 extra 90*s really mattered, but I just didn't know.

I played around with a few other positions, and really didn't find anything suitable.

I just ended up elgonating it out, or using hose ends but causing the hoses to 'flatten' in the middle of the bend.

SO I think I'm going to stick with this, unless somebody can see something really bad with it?

It won't help, but it certainly won't kill it, we use to use a damned similar setup to get our 044 in the nose of the car (we did actually end up switching to hose because the vibration kept slackening fittings, but we do have the pump rubber mounted because of the impacts - it's in a safari car), and losses were small enough that I couldn't rule out it just being the accuracy of the flow/pressure gauges (They're only cheap units, +-4%)

In my opinion - they are full of cr@p.. Certainly any sort of bow or bend in the line will add resistance - but to say that it will "kill the flow" is being a bit over-dramatic..
Most of the guys on forums like that know only one thing - Drag Racing. And if you know and understand most drag racers, they all have to have exactly what the Pro-Stock guys have that are running at the top of their class. Oh yeah - even though their car is a 10-15 year old grocery-getter that MIGHT crack out a 12 second ET,

Ask the 'Stang-Boyz how to improve the flow characteristics of this;



Or even better still - How about this "BRICK-WALL" to the flow;

Or don't Mustang "Squirt Racers" believe in fuel filters?


I think your setup (since it's using full-flow tubing instead of right angle fittings like the one below) is a pretty nice setup.

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Bottom line here is that you have a system that is capable of flowing far more than your engine will typically need - even when being pushed to the limits...

Okay, looks like I'm keeping it then. (good thing too because I played around with it somemore and couldn't come up with anything better, hah!)

I'll tell ya, if you move the fuel out of rear cockpit area there really isn't that many places to put it if you want to keep it out of the path of heat and have everything in a compact package. Plus I tend to go overboard on safety - for example, I could have placed the fuel filter on the rear crossbeam to free up some space (And then have a hose run to my pump and last filter), but doing so would have it above the coolant pipes. And i figured if it ever leaks I don't want fuel leaking on a 220* pipe, heh.

Over-engineering, but hey, that's what happens when your first experience with fuel (cobra) was LEAK LEAK LEAK LEAK LEAK (crappy aeromotive pumps, had nothing to do with anything on my end)