Ok so I've done a lot of research and am trying to get a final answer.

I'm trying to tap a hole for my METRIC DEFI 60MM EGT which uses a 1/8 PT Tap size into the header instead of the standard imperial 1/8 NPT

I've found a chart that shows the thread comparisons but can't find where to buy a tap that will allow this to work.

I've purchased the 1/8PT adapter that allows one to fasten the probe into the header with teflon tape but I don't have the actual TAP to make the correct hole size.

Any comments would be amazing! I've been waiting to install this for over three weeks!

 

I recommend buying the threaded cylindrical metal bung, and have that welded over a spot in which a hole was predrilled into the manifold. There is not enough material in the manifold to provide a sufficient amount of threads without this bung. You can buy these bungs on ebay or from any EGT gage manufacturer. Good luck

 

Can link me to this? I already bought A defi item like this: http://www.rhdjapan.com/images/produ...rmal/Image.jpg

Can I just get this welded you think or do I need another part?

 

1/8 npt half coupling in 316 ss ($4) welded to your manifold on the #2 runner. No teflon, ss and pipe thread (tapered) make a pressure tight seal. If you like you can pick up some Locktite high temp anti-sieze thread sealant (2200*). This is how my defi egt is hooked up.

 

To my understanding 1/8NPT is for imperial only and Metric needs 1/8PT. Is your EGT in Celsius?

Thanks

 

No it's *F x100. D-Gauge. I've never heard of mpt (metric pipe thread) I'll ask my machinist friend tomorrow. I'll post with your answer.

 

My machinist said and showed me the chart and book, no metric pipe thread. He also said not to rule it out, there's alot of thread pitch and count out there. Most likley your 1/8 pt is npt, try and thread it in an npt fitting by hand (no tools) if you get three turns your good. If that doesn't work try the same thing with a bspt fitting. (British standard pipe thread) I hope this helps.

 

Thanks for the follow up I appreciate it. You think I should buy a 1/8NPT tap then? I've never done any welding so I was considering bringing it to a shop and having them deal with it, I cant imagine it would be too expensive. Any thoughts?

Where in CO are you and your shop?

 

I second the suggestion about buying a fitting that is pre-tapped for your Defi gauge sender. You'll need it anyway with a header, which will not have enough thickness to hold a tapped hole anyway.

There are a variety of thread and sizes for EGT gauges. Make sure you read carefully your DEFI manual or look online to make sure you have the correct size and pitch. As I recall, it's not NPT...

NPT does not equal PT: http://www.pneumation.ca/website_pdf...pipethread.pdf

 

I'm in Springs and work for a big fab shop , I don't want to say. If you want it done maybee we can work something out. PM me.

It's either NPTF or NPT , BSPTF or BSPT

If you bring it down we can run it by my machinist for a definate answer.