docmirror

Yes, but does it have the ball which is of such interest to some others?

Jim bailey - 928 International

the point is ....." The word “taper” in several of these names points to the big difference between many pipe threads and those on bolts and screws. Many pipe threads must make not only a mechanical joint but also a leakproof one. To accomplish this, the threads become shallower the farther they are from the end of the pipe or fitting. The bottoms of the threads aren't on a cylinder, but a cone; they taper. The taper is 1⁄16 inch in an inch, which is the same as ¾ inch in a foot.



Because of the taper, a pipe can only screw into a fitting a certain distance before it jams, unlike threading a nut on a bolt. The standard specifies this distance, the effective thread. It also specifies another distance, the engagement, the distance the pipe can be screwed in by hand, without much effort. For workers, instead of these distances, it is more convenient to know how many turns to make by hand and how many with a wrench.

The table shows the distances and number of turns called for in the standard. A tolerance of plus or minus one turn is allowed, and in practice threads are often routinely cut shorter than the standard specifies.

All dimensions are in inches.

American Standard Taper Pipe Threads (NPT) Nominal size
(inside
diameter) Actual OD ,Threads per inch, Length of engagement
(tightened by hand) , Hand tight turns , Wrench makeup turns Length of effective thread

1⁄8 0.405 27 0.180 4½ 2½ 0.260
¼ 0.540 18 0.200 4 3 0.401
3⁄8 0.675 18 0.240 4½ 3 0.408 "
I have commented before about this not being a proper use of the end cap....from a product liabilty standpoint this really sucks.... make a few bucks , be potentialy liable for burning up a guy's car and maybe his house. Yes a number of people are running around this way with no problem but that does not mean it is a good idea just that they got away with it. My guess is the nut must be over torqued to jamb the threads to force it to seal. The concept is as basic as having a sealing ring on the oil pan drain plug , crush washers on the steering banjo bolts.... straight cut threads LEAK.

hacker-pschorr

No need for a ball, that is what the o-ring is for

I'm a bit confused by Shane's post. Drilling a hole through the ball kind of defeats the purpose of having it there in the first place.

Jim bailey - 928 International

the new pick up for the pressure gauge was pipe threaded into the ball with a larger hole in the end of the cap....much like how a metal fuel line seals with the captive nut.

ROG100

Jim,
So if we seal it with the O ring are you still against it?
Roger

hacker-pschorr

Ok, that cleared up the image in my head, sort of.

ROG100

Jim,
How would you do it?
Genuine question?
Roger

docmirror

Ok, O-ring takes place of ball in the existing aftermarket design, right? Folks that don't like the teflon solution after a multi-car, three year test need/want and o-ring.

ew928

Would a copper crush ring (hollow donut) work as good or better than an O-ring.


Really really hate to have anyone come to grief with this.

Jim bailey - 928 International

Unless you are running an adjustable fuel pressure regulator and plan on adjusting it.... I see little point in having a pressure gauge especially under the hood. It might be interesting to have one inside the car to see what happens at full load. But knowing what it is at idle or winging it up out of gear with the hood open is just about useless information. Especially when the sharktuner is now a much better option for later cars than tweeking fuel pressure to fool the computer. I would only have a gauge on the car for the one minute it took to test the pressure or the 20 minute leak down. Something which I have never done on the old very brown 1980 in the last 8 years or so Remember you did ask ! If I did not have a pressure gauge with the correct nut and rounded metal "ball " seal I would probably use a cut off old metal fuel line to make the temporary connection. (Note I have not tested this to confirm the seal)

docmirror

Awright Jim, I'm pretty laid back but really. No one actually has a point about any of the stuff we buy or like to have for our cars. Heck, you're entire business model is built on selling people things that don't have much point.

The safety concern is certainly valid, he's getting through that, and so is the Sharktuner comment, but unless someone is selling sharktuners for < $40, what's the point of any of this really?

It's a cool looking gizmo, at a more than fair price, tested within reason and will give decent results of fuel pressure and leak down at a glance. Why all the hostility?

/rant

Jim bailey - 928 International

There is no hostility as far as I am concerned and you might note that 99 % of what we sell are replacement parts to keep cars running , some might consider that a NEED. But I concede that "cool looking gizmos " are not high on my personal priority list...

docmirror

I would say that 99.99999% of 928 owners have a DD that is used far more than their Porsche. That shoots down the need for a part. As noted by the community, the first batch sold out in less than a few hours. He is now working on a double order for more.

This calls for a Barnum-ism. 'Give'm what they want, and they'll come back for more'. (someone should prolly check my reference for that one though)

Jim bailey - 928 International

P. T. is better known for ..." Every crowd has a silver lining. "

SeanR

The only real reason I want one on my car is for looks only. I've seen a few in our group that have them and it just looks pretty cool.

Of course, I'd also like to have it to see if my fuel system is holding pressure.

I agree Doc, don't really see why this is such an issue. I have Twist wheels on my car, but I suppose stock ones would work just as well.