Pyro gauge installation

[mas360]

The Pyro gauge installation calls for drill and tap into the manifold to mount the thermocoupler.

Does anyone know size of drill bit and tap are needed for this job?

Thanks

[gtspowerstroke]

1/8" NPT Tap. The tap should say on it what size drill. I want to say 3/8" but I'm not 100% sure on that.

[mas360]

Originally Posted by gtspowerstroke

1/8" NPT Tap. The tap should say on it what size drill. I want to say 3/8" but I'm not 100% sure on that.

Is this available at Home Depot?
Tap is usually something like 10-32 or something like that. The NPT must be a different system?

[cpayne6335]

as a ex machinist... I will put my 2 cents in

1\8 npt (pipe tread) uses a drill size "Q" or .332 a 3/8 drill will take too much out and you may not beable to seal your pyro conector

here is a link NPT Tap Drill Sizes - Engineer's Handbook

if it is not a pipe tread then here is a link for a tap and drill

Drill & Tap chart inch / metric

[cpayne6335]

hey, take the coupler with you, and find a bolt that has the same treads. Now a hardware store or tractor supply has tread gauges, then you can make sure you get the right one.

I can not find anywhere where it says what size it is, so I hope my post above helps.

Hint on taping cast, use lots of oil (cutting oil), and take it slow. when taping, go in a few turns and back out some, you might even have to pull the tap out and clean it a few times. Once you break a tap, good luck getting it out!!!!! I have spent to much time exstracting taps, and it is no fun..... let alone a drill will not drill in them! Even the cheap china one are hard to exstract. a screw driver and a hammmer work sometimes if you can bet the tap to back out.

Hope my posts help out.

[mas360]

Thanks for the advice, it sure helps, Cpayne....

[gtspowerstroke]

NPT stands for National Pipe Thread. You should be able to find a 1/8" NPT tap at any hardware store and most automotive stores like NAPA etc. It'll typically say the size drill it needs which I'm almost positive is 3/8" Lettered drill bits aren't very common so good luck finding them. I've used 11/32" drill bit before and it is to big but it does seem to work. Just the fitting has to screw in a little farther so a 3/8" drill should work fine.

The case is relatively soft so it cuts realy easy. just make sure you get it straight. The problem with having to back a pipe tap all the way out then restart it is it can be very difficult to get the threads lined back up just right if you're not familiar with taping. Just go slow and turn it in .5 to 1 turn then back out about .5 turn to clean the ber and continue until you have threads all the way through the metal. It's not hard at all, just pay attention to what your're doing.

[NoRalPh]

Originally Posted by mas360

Thanks for the advice, it sure helps, Cpayne....

You just got bad advice...

NPT is not a "bolt thread" although it may have a similar thread count.

Pipe thread is tapered to seal as they tighten.

[Snake]

We had a helluva time figuring this out too. For the life of me, I can't remember the size drill bit and tap, but I can offer this:

Try it on a scrap piece of flat steel and see what size the probe fits best. I know we tested one size we were told and the fit was a little too loose.

--Snake

[mas360]

That's good idea, Snake. Thanks.