For some reason I am unable to comprehend the wide variety of fuel fittings and tubing connections available for fuel systems these days. I need either an education or for someone to just tell me what to get


I am converting a 68 w/502 to modern port injection. To that end I have the old 68 style tank with no return line provision, a BB Ramjet fuel rail, and a Mallory regulator with 3/8 NPT ports for the fuel rail and AN-8 for the fuel line and return line. Also a Kinsler pre-filter with 8-AN fittings. I also have a modern GM fuel pump module that has the push on plastic o-ring fittings and the fuel rail has yet another kind a threaded o-ring fitting.

To keep things simple, my plan is to forget the GM fuel pump module and go with an externally mounted pump and cut the fittings off the fuel rail and somehow convert them to 3/8 NPT as is on the Mallory regulator.

So here is my plan:

8-AN bulkhead fitting on tank

Short line to pre-filter with 8-AN fittings on each end

Short line out of pre-filter to in-line pump (with ? fitting)

Flex line out of pump (with ? fitting) to replaceable filter (with ? fitting)

Hard line out of filter (with ? fitting) to engine bay bulkhead fitting

Flex line to fuel regulator with 8-AN fitting

RETURN LINE
Flex line out of regulator with 8-AN fitting to bulkhead fitting

Hard line to rear of car.

Flex line to tank.

*also hard lines are 3/8 fuel line and 5/16 return AND I could use some advice on a good pump for this setup

All help here is appreciated. I admit, I'm baffled.

Now if it were a carburetor..............I would probably still be confused

Do you want to use new or the original fuel lines?

If new, stick with 3/8 (-6), 5/16 is -5AN and a bitch to get fittings for. You'll need -5 to -6 adapters to be able to use it.

As for the regulator, get some 3/8 npt to -6 AN fittings and use AN hardware for the rest. You can buy an inline pump that will either have NPT or AN ports (if AN, they usually are a straight cut male o ring boss to an fitting)

If you plan on drilling a hole in the bottom of the tank, don't use a bulkhead, get a proper fuel cell fitting. It comes with nylon washers to seal it and it's flush with the inside nut and slightly funnel shaped so you can get that last bit of fuel out of the tank. Put the return on the TOP of the tank, failure to do so will mean that if you have a full tankt he weight of the fuel will pressurize the return and therefore it will elevate your actual fuel pressure.

If you want to use -8 you will need 1/2" fuel lines or adapters.

Here's some pics of a 69 w/ a 502 ramjet using a 1/2" fuel line and -8 hardware. The stock fuel lines that run to the rails however are only -6 requiring adapters so it's easier to just make it all out of -6 and be done with it. -6 also fits between the body and the frame at the kickup area and can be wrestled in place without lifting the body. -8 is a no go (also some pics of 77 w/ -6 stainless line)

Get a PROPER pump. A lot of people use the aeromotive pumps, I myself use SX pumps. The 69 in pics below has an aeromotive A2000 pump. I used a kickout sump, was bought as a Competition Engineering unit and it doesn't fit worth a damn, easier to just bend one up yourself and buy some weld on NPT or AN bosses

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Here's the 77, the big filter is a prefilter for this application (carbed) but it will be a normal filter when going to EFI. Note that the bulkhead bracket already has a provision for the 2nd (return) line

The line is 3/8 stainless line, flared for 37 deg AN/JIC hardware. You WILL need such a tool to be able to pull this off. The tubing adapters you see for sale are NOT for pressures above about 10psi, the only ones that are are the stainless swagelok ones and if you buy a bunch of those you will have spent more than on a proper flare tool (imperial eastman 400f is a good tool)

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I will use all new lines. I think I will have to run the lines on the driver side and connect to the Ramjet fuel rail at the back of the engine. It's going to be a mess of crap there but coming off the front on the other side doesnt package very well. Do you have any shots of how you plumbed the Ranjet fuel rail?

If the 5-AN is difficult, I can stick to 6-AN fuel and return. That might make things simpler.

Before I completely give up of the GM fuel pump module, do you know where I could find proper fittings for these kind of tube ends:


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There are connector styles that use that sort of a formed collar and an o ring however since there are no tube nuts present and no way to get them on there past the collar those are used for that modern plastic fuel line tubing that you push on???

The only way to use that would be to either flare the ends or use some tough hard line adapters with a steel ferrule.

Those are called bubble flanges. You can have them made at any hydraulic shop. They fit into a hole with an o ring.

Unless that one is supposed to accept rubber fuel line.

Can't tell from the pic....

That's not a bubble flare, a bubble flare is an inverse of a normal (inverted) flare, much like the british girling flare. It's a V shaped flare folded inward, not outward like a conventional inverted flare.

Anyway, a tubing bead like that is normally used for an o ring type seal, like on powersteering systems but again, there are no tube nuts present on the sections of tubing so it's got to be a different style, possibly push on.

Quote:

I just had fuel lines made up they told me that was called a bubble flair. Now I'll have to look to see what I can find.

this is a bubble flare, also called metric or iso flare



the ordinary inverse flare (and these come in double or single flare, depending on the tubing being seamless or not, regular is 45 deg, AN/JIC uses 37 deg but it's the same principle)



This is the o ring bead type


but it's used with a tubing nut just as any other flare:

SEE WHY THIS IS SO CONFUSING!

Your right, it is a pump from a late model Chevy truck with the push on plastic lines and an o-ring.

[color=red]"The only way to use that would be to either flare the ends or use some tough hard line adapters with a steel ferrule"[/color:d901aecf2d]

Is there some way to convert these to a conventional fitting?

What is a conventional fitting? You can convert it to AN if you like.

Do those lines see pressure or just suction? If the pump is after these lines you can just use thoseearls or other brand tube adapters. They have a soft brass ferrule. If you want to make sure it's 100% leak proof and will never come off, assembly the whole deal with the ferrule and the nut packed with some kind of epoxy like JBweld, just rough up the ends with some rough sanding paper.

There are swagelok (and other brand) fittings for hard line that come with a steel ferrule, they bite the tubing better and are for higher pressures but also much more expensive.

You can also silver braze a fitting on the end or have that tig welded.

Here's a tubing adapter on a stock fuel pump. These things are available with female and male ends (the male end readily accepts a hose end)

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