NPT Fitting - Tightening

[cv2065]

Oil pressure sensor in the block is 1/4 NPT. First off, what fitting material is better in the block? Brass or Stainless? Second, I’m not sure on the number of turns. Recommendation is 1.5-2 turns after hand tight, but I’m only getting about 1/4-1/2 turn on the fitting after hand tight before I’ll have to start really getting on it with the wrench. Don’t want to risk distorting the threading.

[Ford & Jeep Fan]

any chance you have a excessive amount to Teflon thread tape on the threads?? and just remember if this is an electric gauge sensor it might have to be grounded if it is a one wire sensor. Too much tape can insulate the sensor.

[cv2065]

any chance you have a excessive amount to Teflon thread tape on the threads?? and just remember if this is an electric gauge sensor it might have to be grounded if it is a one wire sensor. Too much tape can insulate the sensor.

I typically don’t use Teflon tape, only Permatex high temp thread sealant.

[edwardb]

Either brass or stainless is OK. But brass is softer and may allow you to turn further. NPT is a friction fit so resistance is normal. But it should turn further than you're experiencing. Obvious, but make sure you're not cross threading. Over the years, I've had several NPT joints that I didn't feel turned far enough, so used an NPT tap to cut the threads a little deeper. That helped but may not apply in your situation. You don't want chips or whatever in your engine or sensor. Good call on the Permatex.

[CraigS]

I'd go to the hardware store and get a brass fitting in 1/4NPT. Whichever style is the least expensive that has a hex for a wrench. Use this as a test piece so you can compare how far it threads compared to the one you are using.

[cv2065]

Thanks guys. Good idea. I'll get a couple of brass fittings and see how far it lets me get as the brass won't distort the iron threads. The hole did of course have a plug in it from factory that threaded flush but was only the depth of the hole. These fittings will thread the same depth before getting tight, but there's about 1/2 of the threads left showing. Maybe I just answered my own question as I'm sure you don't want too much of the fitting extending into the block.

[rich grsc]

What hole in the block are you trying to use

[cv2065]

What hole in the block are you trying to use

Driver's side, the one to the left of the oil filter.

[edwardb]

Thanks guys. Good idea. I'll get a couple of brass fittings and see how far it lets me get as the brass won't distort the iron threads. The hole did of course have a plug in it from factory that threaded flush but was only the depth of the hole. These fittings will thread the same depth before getting tight, but there's about 1/2 of the threads left showing. Maybe I just answered my own question as I'm sure you don't want too much of the fitting extending into the block.

Normal for an NPT fitting to have threads exposed.

[gbranham]

Here's how mine looks.

208530

[cv2065]

Here's how mine looks.

208530

Nice. Thanks Greg. Mine looks similar to that. Did you get 1.5 to 2 turns after hand tight? I think I'll just use the goodntite method and adjust if needed later.

[gbranham]

I probably got two turns. Didnt really pay attention. I just ran it in and snugged it up.

[Avalanche325]

I wouldn't worry about how many turns you get. Just give it a little grunt and you are done.

[cv2065]

Funny how these intakes are tapped. Looking inside, some of them look pretty rough. I installed my coolant temp switch into the 3/8" NPT hole on the driver's side and it screwed all the way down until about 1/8" from the bottom where it tightened up as one would expect from an NPT fitting. Not as much play as the other NPT holes.

[rich grsc]

NPT are a tampered fitting, if there isn't much depth to the hole, you can't run the tap in very far, thus they tighten up quickly. If the tap is run in too far, you can't get the fitting properly tightened.

[cv2065]

NPT are a tampered fitting, if there isn't much depth to the hole, you can't run the tap in very far, thus they tighten up quickly. If the tap is run in too far, you can't get the fitting properly tightened.

Let's hope Edelbrock didn't run the tap in too far. I did get it tight before it bottomed out and used high temp thread sealant, so I'm fairly confident that it won't leak, but if it does, then I guess I'll be drilling out the hole to 1/2" and re-tapping? Maybe I should just get this done before adding fluid.

[CraigS]

I would only do drilling and tapping as an absolute last resort and only if you have a leak. I worry that the debris that is bound to be created could get into the oil passage.

[Jeff Kleiner]

... I did get it tight before it bottomed out and used high temp thread sealant...

Then you're good to go. Carry on.

Jeff