muz

I've got some 1/4 NPTF to -6 adapters for my lift pump but they are very tight. I know they are tapered to seal but they literally turn in about 1.5 full turns and lock off tight so you cant do them up anymore by hand. I don't want to force them anymore but they are facing the wrong way and have loads of thread left. The old fittings went in about 4-5 full turns. I this just how they are or is something wrong?

focusv8

Are you certain the lift pump threads are Taper and not parallel?

muz

Well, on the pump specs, it says they use a 1/4 NPTF fitting. I thought all NPT's were tapered threads so they seal? I ordered 1/4 NPTF to -6 so they should be the same?

the_frozen_one

iTrader: (1)

As above sounds like taper to parallel binding

muz

But the pump outlets and the adapters are both NPTF?? I was of the understanding NPTF meant National Pipe Tapered Thread - Fuel. So can't see either thread being parallel?

The pump has 1/4 NPTF and the Adaptors are 1/4 NPTF one end and -6 AN on the other. I've compared the new Adaptors to the old ones and the thread etc are the same, they just seem very tight and I haven't even PTFE taped them yet as I was dry building it all first to check I have the right angled fittings and enough hose. Surely the tape would make them tighter again...

stevieturbo

what pump is it ?

I'd always be cautious about tightening alloy taper fittings. Very easy to wreck the threads

muz

It's on a Facet Red Top.

stevieturbo

It does say they are NPT fittings, so would be taper.

Is that an 044 beside it, or a lesser pump ? That red top is no match to keep up a fuel supply to an 044.

What sort of power are you expecting to make ? Red top only seems to be rated for 180lph.

muz

It's a Bosch 979. A single Red Top will keep up for my power circa 280-300. Or so I've been told, anyway.

stevieturbo

Based on a quick google, it suggests circa 240hp max, although 180lph would support more than that

You'll have to return fuel from the reg to the swirl tank. And at anything over the red tops flow abilities, the swirl pot will be emptying. So just bare it in mind.

muz

Yeah, the 240 figure is as a stand alone fuel pump. To act as a lift pump to the swirl pot it is man enough. The fuel rail returns to the swirl pot, no worries there.

Calculating everything we found, at full load from the 979, without the Red Top supplying fuel around a corner the 1 litre pot will provide 31 seconds of protection before emptying, so that's plenty.

muz

I worked everything out a long time back and others said the single Red Top would be fine for the power.

the_frozen_one

iTrader: (1)

I'm sure they are, obviously I don't know the ins and outs of your pump etc but from experience if a pipe thread instantly binds in tapped hole it's usually parallel and binding on a taper.

stevieturbo

And using a straight male-male -6 to 1/4 NPT and then a 90deg fitting would have been better, and given you a full range of rotation on hose position

muz

I did mean to order them that way around but I confused myself when I put together the order . I might email Torques and see what they say.

muz

Yeah, I can see what you mean. It does seem strange.

the_frozen_one

iTrader: (1)

I've just googled the facet red top and it's got "npt" fittings. I then googled npt and on the wiki page (admitted not a definitive answer but still) it says:

"A semi-compatible variant called National Pipe Taper Fuel (NPTF), also called Dryseal American National Standard Taper Pipe Thread, defined by ANSI B1.20.3, is designed to provide a more leak-free seal without the use of teflon tape or other sealant compound. NPTF threads are the same basic shape but with crest and root heights adjusted for an interference fit, eliminating the spiral leakage path."

Sounds like you may be trying to fit nptf into npt? And the slight difference may be causing the problem? It seems that nptf is a slightly different profile so no tape is needed? Maybe you need npt and tape?

muz

Got it all sorted now.