Basic gauge installation help desperately needed!

[MMead]

I know everyone says the installation of the EGT, transmission and boost gauges is any easy job, but I have been struggling with it for days and haven't even gotten the gauges out of the boxes yet!!



I went to Home Depot last night to buy the drill bit and thing you need to make the threads. The Home Depot guy first asks me if I wanted fine, normal or wide threads. Of course I had no idea. Then he asks what size drill bit and tap I need and I told him I was trying to install a 1/8 NPT tap and that was all I know. That didn't do the Home Depot guy any good since he barely knew more than I did. Neither one of us knew what "NPT" meant.



Then I try and go get the tap out of my truck to show him, but when I looked at the probe and the fittings that came with it, I wasn't even sure I knew which part was the tap!



If someone could give me some very simple/basic instructions on how to install my new Isspro EGT probe, and what materials I'll need, it would be greatly appreciated.



I've also tried searching for good instructions on how to hook up the electrical aspect of the new Isspro gauges with little luck. The drawings that came with the gauges is useless with my very limited wiring knowledge. Any help on this front would be great as well.



BTW: 1. I've got the three gauge window pod, 2. My skills as a mechanic are limited to changing my own oil and filters, and 3. For my own personal reasons (right or wrong) I am definitely installing my probe on the elbow after the turbo.



Thanks in advance for any help I can get.

 

[Graphic man]

NPT means National Pipe Thread

an automotive store is a better place to go

it will tell you on the tap box what size of drill bit you need,



you should go pre turbo with your EGT i am not sure about your gages but in most cases you will need to weld on a piece to the exhaust pipe to screw in the probe if you do it after the turbo,

drilling and tapping the exhaust manifold is not hard!



as far as the wiring goes you have a red wire (12volt power key on) you need a 12volt test light and you can tie it into the fuse panel, test it with the key on and off to make sure it is key on power,

the black is a ground, attach that to something metal



i hope this helps !!



Scott

 

[JHardwick]

I think the elbow is thick enough to drill and tap without welding a bung.



You need a letter "R" drill for the 1/8"-27 NPT. There is no course or fine thread an a tapered pipe tap.



No offense, but my suggestion is to enlist the help of a friend or local TDR member. This way you get the satisfaction of doing it yourself and have a better chance at success without driving yourself crazy.

 

[JHardwick]

Then I try and go get the tap out of my truck to show him, but when I looked at the probe and the fittings that came with it, I wasn't even sure I knew which part was the tap!

For the sake of clarity. The drill bit makes the hole and the tap puts threads in the hole.

 

[rbattelle]

No offense, but my suggestion is to enlist the help of a friend or local TDR member. This way you get the satisfaction of doing it yourself and have a better chance at success without driving yourself crazy.

I agree with everything JHardwick said. But I do think you have 2 options:



1. Cut your losses now and get a local TDR member to help you out.

2. Take a deep breath, step back, and learn to drill and tap holes before proceeding.



I'm a big advocate for people learning to do mechanical work for themselves, so although option 1 is easier, I encourage you to consider option 2. You should consider buying a copy of Machinery's Handbook (link ). It is the Machinist's best friend (in my opinion). It discusses everything from the periodic table to chains to taps and dies.



Tapping a hole involves 2 tools: a drill and a tap. A tap is a hand tool (although it can also be used in a machine like a mill, but that's beyond the scope of this discussion). It resembles a large bolt with four large grooves machined in it. This page has some pictures of taps on it. Buying a tap is not something I think should be taken lightly. Taps and dies (taps cut internal threads, dies cut external threads) are best when purchased as a quality investment. Good taps make good threads, and it's worth it to invest in a good one.



According to my handy little Starrett tap/drill cheat card, a 1/8-27 NPT tap requires a 11/32 twist drill. In order to tap a hole, you first drill the material using the 11/32 bit. Remove any burrs that develop.



Then, apply some cutting fluid to the tap and carefully start it in the hole. Be sure to keep it perpendicular to the material (parallel with the walls of the hole). I was taught to rotate the tap in clockwise 2 full rotations, then counterclockwise 1 rotation. I usually go a little slower than that, depending on the material. NPT taps are slightly more complex than straight threads, as the tap is tapered (it's larger diameter at the top than at the bottom). You want to continue driving the tap into the material until the hole size is just right to engage about 1/2 - 3/4 of the fitting that's going to be screwed in. I think there's a thread engagement standard in Machinery's handbook, but my copy's at work. With NPT holes, I tap to about 1/2 way up the tap, then start checking for fit with the fitting every rotation or so until I get the fitting to screw into the hole a "good distance". I go slow (I'd make a bad high-volume machinist... or I'd make a ton of money charging people an hour labor to tap 1 hole :-laf )



This is all very hard to explain by typing, and it's best to have someone demonstrate it to you and then to practice on several holes until you get a feel for it. It's not hard, it just takes a little practice.



I have attached a picture of the tools required for tapping (except the drill bit). On the left is a 1/8 NPT tap inserted in the tap handle. On the right is the cutting fluid I use (use whatever you want, I make no claims as to the superiority of that particular fluid).



Tapping is not hard. Making a good threaded hole, however, is a skill that takes a little practice. You can do it, but you must be willing to take some time to learn how to do it right. I think of it as an art. Your truck won't die next week without a pyro.



I tried searching for "how to tap a hole" on Google, but didn't find anything useful.



This link has a brief description.



I hope I've helped a bit. There are lots of machinists on here (I'm no machinist... I'm more of a wanna-be machinist) who can point out if I've said anything wrong. JHardwick's a good example...



-Ryan

 

[testraub]

Your local Sear's should have the tap. Mine did. Do a little practice. drill and tap a few holes in a scrap piece of metal, make sure everything works after a few trys you should have the knack. As with everything in life... take it slow and easy. You shouldn't have any problems, but you can always ask for help here, or take evrything out to your local machanic and let him do the work. Good luck on your project!

 

[JHardwick]

Very good Ryan, I wish all engineers took the initiative to be that hands on Oo.



A couple things though ... ..... in iron, it is not as important to back the tap off, although it does get some lube back into the cut. The reason for backing a tap out is to break the chip you are creating, iron donesn't really create a chip, but steel does. That said, 2 turns in and 1 out is too much. Every half turn in and a quarter back breaks the chips nicely. It really is no more of a motion then a half turn with the tap handle (180*) and a quick snap back before doing another 180* of the handle.



Secondly, a good rule of thumb on a tapered thread is to tap 5-7 threads from the shank of the tap. That should give you 3-3. 5 turns of hand tight engagement on the fitting.



On a side note, the "R" drill will give you 72-77% full thread according to the chart I use. If I remember correctly the 11/32" on the Starrett chart is 68% to 70 something. Those percentages are for straight holes, an NPT should be taper reamed after drilling to be abslolutely correct. Percentage of full thread refers to the flat on the crest and the fillet in the root on an OD thread (opposite on an ID thread). A 60* American thread is based on theoretical sharp points, both root and crest, but is not done that way to eliminate possible interference due to tool break down. OD threads are actually measured with wires and mics to gage the pitch diameter ... ... . just thought I'd give you some food for thought :-laf



Anyway, now that MMead is waaaay confused, drilling and tapping is not black magic, but then you have wiring.



No offense MMead, but your confusion scares me and I'd rather see you get some help rather than have to do it over. I'm sure there is a TDR member close who would help you for a cup of coffee ... ... ... ... or a cold one You can get the job done, learn a few things and make a new friend!

 

[JWChessell]

RBatelle:



What a nice, clear, c-a-l-m explanation. You should copyright those paragraphs!

 

[rbattelle]

As I expected, the real machinist chimed in with some excellent points. Now that you mention it, Jeff, the method you describe of 1/2 rotations clockwise followed by 1/4 rotations counterclockwise is exactly the way I do it. I just didn't think about it when I was typing it, and that's not the way I was taught to do it so I actually assumed it was technically "wrong" in some way. Admittedly, I learned on aluminum which is a lot different to tap than iron. Anyway, glad to hear I'm tapping iron correctly.



[Thanks, JWChessell... you're making me blush]



-Ryan

 

[JHardwick]

As I expected, the real machinist chimed in with some excellent points.

I didn't mean to sound demeaning if I did

 

[rbattelle]

I didn't mean to sound demeaning if I did

I didn't think you were being demeaning at all. You are a real machinist, and and you pointed some excellent additional guidance. I was hoping you'd do so. You should know I have nothing but the greatest of respect for you, Jeff.



-Ryan

 

[MMead]

Thanks very much for all of the information! It was exactly the information I have been trying to find. This post alone was worth the annual subscription to TDR.



I'm embarrassed to say this... but I don't own a power drill. :--) All I've got is an 18volt cordless drill. (I know how bad this sounds). Will this be good enough for the job or do I need to borrow a real drill?

 

[red-rider]

your 18V drill should work perfect I used the same on mine.

 

[SRadke]

I did one yesterday with an 18 volt cordless drill, no probs It was even a bigger probe with 1/4" npt. I'll watch this thread closely now too so write back if you have more specific questions or get hung up.



-Scott

 

[SRadke]

One more thing I should add with reguard to your "easy gauge install" comment, I spent 4 hours yesterday installing 3 gauges and just over 1 hour installing a set of injectors in a 24 valve. Gauges are a PITA, no doubt about it.



-Scott

 

[LightmanE300]

Wow I guess I got lucky then - the hole in my manifold is the first one I've ever tapped! I don't have pieces of scrap metal or anything around to practice on, so I read as much as I could and went for it. When I went to home depot they had 1/8" npt taps sold in combination packages with the 11/32 drill bit. Makes it pretty easy to get the right one The home depot guy had no clue and I ended up finding it myself after he said they didn't have them. .



I just noticed MMead is installing the probe post turbo for sure. It would seem that most people are giving advice for drilling/tapping the manifold... unless the post turbo area is iron as well... While I totally disagree with this practice (post turbo location), I think it will be a lot less stressful- no worries about sweeping up shavings, greasing bits, or dropping the turbo. Just so you know though MMead that your readings post turbo will not correlate with anything folks on the forum are talking about, since most have pre-turbo probes. There is no hard and fast 300 degree rule that you can add to your post turbo measurement to estimate EGT's in the manifold.

 

[rbattelle]

I'm embarrassed to say this... but I don't own a power drill. :--) All I've got is an 18volt cordless drill.

Actually, I don't either. I have a 13. 2 volt cordless I bought some years back from Sears. But I do own a Delta floor drill press (big monster... 200 lb) that is the "pride and joy" of my poor-man's machine shop.



-Ryan

 

[MMead]

Once I get the elbow tapped, do I understand correctly that the probe should only be hand tightened into the hole? Seems like it would vibrate out pretty quick in that location.



JHardwick,



I noticed you said the hole should be "taper reamed". How do I go about doing that?



Thanks again.

 

[SRadke]

The elbow is cast iron also, though not as thick. Put a little high temp never seize or "anti-seize" compund on the threads if you ever plan to get it back out and snug it up with a wrench. Pipe threads are tapered so the "hand tight" comment back a few posts was a refrence to aquire the correct depth.



As for a tapered reamer, don't wory about it. Just drill and tap. The reamer would come into play if you were really concerned about having exactly the right amount of thread through the depth of the hole, which we're not.



-Scott



Edit: I noticed it wasn't mentioned earlier you'll want to drill your hole as square as possible (90°) to the surface of your material and tap the same way. If you're hole is crooked you have to tap it crooked and that is not and easy task.

 

[nickleinonen]

Once I get the elbow tapped, do I understand correctly that the probe should only be hand tightened into the hole? Seems like it would vibrate out pretty quick in that location.



JHardwick,



I noticed you said the hole should be "taper reamed". How do I go about doing that?



Thanks again.

install the probe adapter piece into the hole hand tight [make sure to put some antiseize on the threads] and tighten it with a wrench about 1/2 to 1 turn [until it feels sorta tight]. it won't leak, and even if it did a bit, the carbon will build up there to block the leak after a while.



as for reaming the hole, don't... we don't need to get into that much precision here. just drill the hole [i used a 11/32" for mine with engine running] and then tap the hole. go slow with a greased tap and check the fit of the probe adapter every so often. you don't want to go too deep, as the threads are tapered, and if you tap too far, the threads can become too wide so the adapter will bottom out against the manifold and still not be tight



if you haven't tap'd a NPT thread before, it would be a good idea to practice on some scrap steel [1/8" - 3/16" thick piece] and you can test fit the adapter there to see how it goes in when you tighten it by hand, and then a little bit extra with wrench