Fuel line ???

[esff32]

I'm hoping someone can educate me. I have a Holley fuel pressure regulator that has 3/8" NPT ports on it. I'm assuming this refers to the orifice size, not the thread size. The 5/16" fuel line ff supplies has a thread size of 1/2"? I need an adapter to go from 3/8" NPT to 1/2" flare? I have looked all over for such an animal and it is not as easy to find as I thought.

I also would like to put a gauge on one side so I assume I would need a 3/8" to 1/8" 90.
Please educate me and point me in the right direction. Thanks for the help guys.

Evan

[68GT500MAN]

The Holly regulator uses 3/8' NPT fittings in and out. The pressure regulator gauge port should be 1/8" NPT (the gauge will screw right in). Look at Summit or McMaster Carr for the 3/8NPT to 5/16" tube adaptor (or call Forte's).
Hope this helps,
Doug

[esff32]

Thanks for the help. The two outs on the regulator are 3/8 npt so I will have to get an adapter to step it down. I also thought it would be nice to put an elbow so the gauge faces out. So the brake line fitting nut is considered a "tube" fitting not flare?

[wallace18]

Speedway also sells the adapters.

[esff32]

Thanks. I looked on their website but I'm not sure if the size of the fuel line (7/16) is what to order or? The threads on the 7/16 fuel line measure 1/2" when I put the micrometers on it. I realize it is the same type of fitting that goes in the bottom of a radiator for trans cooling lines. If someone has a link they could send me, that would be great. I can't be the only one that wants to plumb the hard fuel line into the bottom of the regulator.

[esff32]

Does anyone have any idea if this fitting will work with the factory five gas tank pickup. The kit comes with a couple of these for the fuel filter to attach to the flex line. I would like to use these to attach to the filter if possible, not sure if it is the right size. Any help would be great. Thanks.

[steve73]

I had similar problems last year, and since its not fresh in my mind I can't quite remember what I did, but when I get some time I will take some pics of my setup and send them through. I do know that I ditched the return line altogether and increased the main fuel line size -just can't remember to what size. Send me your email and I will send you some pics. Thx.

[esff32]

Thanks Steve. PM sent

[CHOTIS BILL]

I would also like to know if the Russell part will work on straight SS tubing and also
Russell Performance 640863 - Russell Fuel Rail Fitting Adapters
For the -6 tubing. If not Breeze has some that work for both the 5/16 and 3/8 tubing.

Bill Lomenick

[tirod]

Threads are diverse. NPT is National Pipe Thread, which isn't the ID of the opening, but includes the wall thickness of the pipe. Since the thread is on the outside, it's much larger, and tapered to seal under torque. Sometimes, it takes a lot to get it liquid tight under working pressure.

Brake lines are 45 degree invert flare, and typically use thread and pitch sizes differently than bolts to prevent using them as block offs.

Adapters are often available at the local parts store, it's a matter of knowing what the specific description of each, male and female, too. It becomes a recitation of specifications to identify it, such as 3/8NPT to 3/8flare - but the supplier might only print 3/8 x 3/8 on the package.

Due mostly to sales volumes and some liability, not all combinations of adapters are carried. Each system was meant for it's particular purpose, NPT for water pipe got carried over to cast iron engines early on, then 45 invert flare for high pressure brakes became a fuel line standard pre EFI. Add more confusion with AN/JIC, propane is it's own stuff, and it gets obtuse quickly. Every field of plumbing fluids or gases tries to use it's own, for good reasons. Pressures, sealing, and the corrosive nature of the medium all create different requirements. Add in manufacturers trying to sell something with an inclusionary port system - NPT works better than some special proprietary system, and it all needs to fit back to production car standards.

The key is to know exactly what each tapped or threaded aperature is exactly, and then the adapter becomes a matter of looking it up in a parts table according to the dominant field it was designed for. Next time at the parts house, if you see a counterman and customer looking at little bits of brass with one of those massive binders out, you know they just might be in for a half hours worth of guessing.

Worse yet, its the third trip on a Sunday.

[esff32]

Thanks tirod. I appreciate the detailed info. I was getting frustrated because apparently they don't make the fitting I was looking for so I was running around in circles. I went AN on everything instead.