Dual Feed Fuel Line Setup

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KOZ45

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While my carb is getting rebuilt, I need to buy a dual feed fuel line.......

With or without a pressure gauge?

Hard line or braided? Personal preference or does it matter at all?

I assume the hard line kits are all the same spacing?

Anything else I need to get or should know?
 
I personally prefer the hard line. No the spacing is different on some carbs so you’ll need to know the center to center if you go hard line. Also the threads for the carb bowls are different if you need to swap them. Pressure gauge port is a good idea for troubleshooting. How ever personally once pressure is set or known I’d remove the gauge. The heat and vibration plays havoc on them and a fuel leak on the manifold or anywhere is never a good idea.
 
If you have a mechanical pump, save some cash and forget the gauge; but if you can get a dual-feed with a gauge port, that might be useful someday, altho in all my years, (About 51 driving,lol) I have never needed to check my pressure.

I don't like the braideds, but the first thing I do with a hard line is split it and jumper it so I can take the bowls off independently without fudging with the bowl fittings. Plus that solves the center-spacing issue.
 
Yes I have an Edelbrock mechanical Performer RPM Street fuel pump
 
I like the Holley parts. 34-150 and 34-160 for the 4150 and 4160 respectively. Simple and effective.
 
Stay away from the cheap lines! I have been thru a few and the threads arent right , the plating sucks and the tubing is thin .
I would recomend a gauge port if you are running an Edelbrock or Carter . They are super sensative to pressure and mechanical pumpscan vary alot .
My Edelbrock pump was putting out over 8 psi which will (did) flood an Eddie carb . Chased that demon for a while before I figured it out .
 
I wish someone made a non-chromed dual feed holley line with a port .
Just a really well made functional one .
 
I like the Holley parts. 34-150 and 34-160 for the 4150 and 4160 respectively. Simple and effective.

Dual Fuel Feed Line
34-150; $45 shipped

Fuel Line Fitting
34-21; $32 shipped

PSI Gauge
26-500; $40 shipped

Lost of money to be tied up into this........wow
 
I believe the 5/8 18 might be for a demon/ barry grant carb, or maybe a carter/edelbrock. The older holleys used 7/8x20 for the fittings into the bowl, but then depending on which adapter bowl fitting you use determines the hard line size you need. I don't know for sure what the new holleys are using.
On mine i use a pressure regulator on the passenger inner fender, with a gauge, two braided teflon lines (alcohol in the pump gas) to dash 6 an fittings into the carb. With all an fittings you're right, it is NOT cheap.
If i was just trying to hook up a holley to a mechanical pump, i dont know what i would do. I cant find anything of quality that i dont think is overpriced, and even the garbage chinese stuff is too much money imo.
 
Thanks for the info and help

I got a Holley hard line, Summit barb fitting and a Mr. Gasket gauge for around $70 shipped
 
Well the Holley 34-150 line does not fit

It lines up about perfectly with the carb fittings, but will not screw in to the carb

The fittings on the lines are too small to thread into the carb ports

Do I just need to buy two fuel bowl fittings?

The Holley lines uses 5/8 x 18 inverted flare inlet and outlets.........so I assume the current fuel bowl fittings in my carb are 3/8?

Any ideas or suggestions?
 
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I ordered two Holley #26-26 fittings that should work

$14 shipped I can't complain
 
Dual Fuel Feed Line
34-150; $45 shipped

Fuel Line Fitting
34-21; $32 shipped

PSI Gauge
26-500; $40 shipped

Lost of money to be tied up into this........wow

Welcome to hot-rodding. If you are going to count your penny's, get out while you are alive. If you want to save some money, don't buy retail. Swap meets, Craigslist, Websites, etc.
 
Dual Fuel Feed Line
34-150; $45 shipped

Fuel Line Fitting
34-21; $32 shipped

PSI Gauge
26-500; $40 shipped

Lost of money to be tied up into this........wow

I guess if you want it "right now". I got my gauge for 17 bucks shipped. The dual line was 41 shipped. The fitting I used was 5/8 18 to 1/2 20 brake line adapter for 4 bucks since I run hard line everywhere I possibly can.
 
Well the Holley 34-150 line does not fit

It lines up about perfectly with the carb fittings, but will not screw in to the carb

The fittings on the lines are too small to thread into the carb ports

Do I just need to buy two fuel bowl fittings?

The Holley lines uses 5/8 x 18 inverted flare inlet and outlets.........so I assume the current fuel bowl fittings in my carb are 3/8?

Any ideas or suggestions?

It fits. You have to play around with it. You need to be careful with it though. They aren't made like they used to be. They used to be so thick, you could use them for a weapon in a Portland riot. now they are easily bent out of shape. It WILL fit. You just have to tweak it here and there. There it is screwed right onto the 800 DP on the 400. I did get a male 1/8 to female 1/8 90 fitting since Holley put the gauge hole in the flat that faces DOWN towards the intake in their infinite wisdom.

400 RIGHT.jpg
 
I needed new fuel bowl fittings, larger ones

It works now and will thread in

Question..........teflon tape on the threads for just the dual feed line?

The fuel bowl fittings do not use tape, just the thin metal washer right?
 
I needed new fuel bowl fittings, larger ones

It works now and will thread in

Question..........teflon tape on the threads for just the dual feed line?

The fuel bowl fittings do not use tape, just the thin metal washer right?

Yes, just on the pipe threads for the pressure gauge. The fuel manifold itself is inverted flare. Inverted flare seals with the flare if the ling and the male "button" in the float bowls.
 
JUST SAY NO to Teflon tape. Those are brand new flare fittings on that line. You wouldn’t put Teflon on your brake line , would you? I get a lot of carbs in that Teflon tape is the culprit that sent them to me.
 
I wish someone made a non-chromed dual feed holley line with a port .
Just a really well made functional one .
Yup. Used to be non-chromed ones at every store. Now pretty much unobtainable.
One advantage of chrome is it that it minimizes radiant heat absorbed.

@KOZ45
For what you are doing - steel line is best.
The flexible ones can be handy when swapping jets at the track, but they all have issues that usually outweight that slight advantage.

Fitting sizes. Again for what you are doing, 5/16 lines up the carb has advantages. One is that they have more room to put both wrenches on when installing and removing. 5/16 line to each bowl is plenty large enough that even at wide open throttle there will be plenty of fuel available to refill the bowls. That is, unless this is sitting on an engine which will be putting out more than 400 hp.
If you've already committed to 3/8 lines and fittings, that's OK. Just know they are occassionally a PIA.

For NPT threads on the fuel system (or cooling that matter) my suggestion is a small amount of specialty pipe thread sealant from Locktite.
 
upload_2020-9-10_15-29-28.png


The adapter fittings seal to the bowl with a gasket on the flat surface.
The black coated metal gaskets from Holley are good.
upload_2020-9-10_15-35-46.png

Other hard gaskets are generally OK.
Thick plastic gaskets can loose their strength when heated to temperatures occassionally seen in the engine compartment. They will then leak and can not be tightened until cool. I've posted pics of this.

This is a steel adapter fitting for a 3/8" inverted flare.
upload_2020-9-10_15-40-40.png


As you can see there is little room for the open end wrench. I've ground down a box wrench into specialized flare wrench but not neccessary.
Get it tight. Then install the lines. If you have to remove the feed line, use two wrenches.
upload_2020-9-10_15-44-34.png
 
After a few variations, including a self made hard line setup that worked well for some time, I bought the fancy chrome line with the gauge port and the lines were filled with some kind of brown dried up garbage.
Read the reviews and discovered I wasn't the only one.

The line seemed fine otherwise, but the T fitting was aluminum or some soft metal.
Sent it back, pos.

Went an fittings with ptfe braided lines. Yes, more $ but never an issue since.
 
One advantage of chrome is it that it minimizes radiant heat absorbed.

Not on the new ones it doesn't. Have you seen the newer generation from Holley? They are the thinnest, crappiest cheapest things you've ever seen. I had to be super careful with mine when I was installing it that I didn't bend or break it. I remember the old ones were thick as could be and you could barely bend them. These new ones, it's hard not to bend them. They are also crappily soldered together. Just junk. And what makes it worse, I HATE braided line and refuse to use that crappy lookin stuff.
 
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