Like to chase the bottom 3 or 4 threads in the head were the adapter screws into. Understand the head hole is 1/2 BSPT thread and took my adapter to local mechanic to confirm, he walked over to a box of fittings, picked up one and screwed my adapter in. He said, need a 1/2 American tapered pipe thread tap. Explained to him, suppose to be 1/2 BSPT, according to him, that my be, but a 1/2 American will work, saying, will they might not be identical, they are interchangeable. Would the experts please weigh in.
Adapter, Temp. Sending, 78 2F
- Thread starter DSjachna
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Temp Adapt
Been buying and selling 1/2" NPT for many many moons. You'll also find that many other locations on the head take an American Thread fitting.
Been buying and selling 1/2" NPT for many many moons. You'll also find that many other locations on the head take an American Thread fitting.
Why would you use an adapter?
Rudi
Rudi
Rudi:
The probes on mechanical water temp gauges are really long for some reason. The depth of the area in the head where the probe screws in is really shallow (less than 1/2") on every head I have seen. The probes bottom out unless you put an extension pipe in the hole. I have always used standard U.S. tapered pipe in the heads. They screw right in and don't leak. You can see one in this photo.
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This statement is wrong. All pipe threads used on a 2F engine (at least through '78) are BSPT. People that say there is no difference, do not care about the difference. I know, "well it does not leak" does not make it the right method to use. If you want to use the right tap then go to McMaster.com or MSCDirect.com.
You can force the issue but I prefer using the appropriate tools. NPT uses a 60 degree thread profile and BSPT uses a 55 degree thread profile. The threads per inch is also different for 1/8" to 3/8" pipe threads.
1/8" pipe NPT 27 TPI, BSPT 28 TPI
!/4" pipe NPT 18 TPI, BSPT 19 TPI
3/8" pipe NPT 18 TPI, BSPT 19 TPI
1/2" and 3/4" pipe have 14 TPI for both NPT and BSPT, again with the variable being the thread profile. The only time I would consider using an NPT tap would be in an emergency where my options are limited. I would correct it when I got home. However, I carry a set of BSPT taps in my tool box.
For what your trying to do, just find an internal thread deburring tool like a Noga or similar. Much cheaper than a tap, and it'll save your life multiple times. Disclaimer: I'm assuming the threads in your head are basically fine but need a bit of cleanup. If threads are trashed you'll need a tap.
http://victornet.com/subdepartments/Other-Thread-Repair/1420.html
http://victornet.com/subdepartments/Other-Thread-Repair/1420.html
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On my first V8 swap I drilled the head and tapped it with 1/2" npt tap and it worked fine with no leaks but was a pain to drill and tap. The next V8 I didn't want to do that again. IIRC the head was tapped from the factory with 3/8" npt.
I took the factory Toyota adapter and cut the treads off then took a 3/8" nipple and cut the threads off one side and welded it to the stock Toyota adapter.
I took the factory Toyota adapter and cut the treads off then took a 3/8" nipple and cut the threads off one side and welded it to the stock Toyota adapter.
The 1/2 x 14 TPI BSPT is $36.75 on page 2538 at McMaster.com. It is $35.24 for an imported tap on MSCdirect.com on page 377. Both companies are among the largest distributors of hardware and tools in the world. They both have very reasonable shipping cost.
Found this one by Merlintools on Amazon...$23. Did a little search on Merlintools quality, seems to be a decent quality tool company for the money.
http://www.amazon.com/RC-ZG-BSPT-Pipe-Taper/dp/B008EJ75NY/?tag=ihco-20
yes you should buy one so the rest of us can borrow it .
For anyone needing to know, the Block Drain plug threads are 3/8-19 BSPT.
Thanks for you info and input Coolerman!
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Thanks for you info and input Coolerman!
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