Can anyone tell me what thread size the original radiator petcock is for a 1917 Model T touring? Is it a 3/8" fine?
Ralph,
It should 1/4 NPT Nation Pipe Tread.
http://www.modeltford.com/item/3079.aspx
Jim
All of mine are 1/8" National Pipe Tapered. There is no such thing as National Pipe Tread LOL!
Royce, thats interesting, i have two new Brassworks radiators and one old Ford and they are tapped for 1/4"NPT, the oil petcocks are 1/8" NPT.
Rick
Original equipment Ford used 1/8" pipe for both radiator & c.c. petcocks. I recently installed 2 new Brassworks rads. and they were 1/8" pipe.
National Pipe Thread: National Pipe Thread Tapered Thread (NPT) is a U.S. standard for tapered threads used on threaded pipes and fittings. It amounts to the same with the "H" or without it.
I've purchased a number of Brassworks radiators. All have 1/8" NPT petcock holes. Just like the originals.
I was wrong, it is 1/8" NPT (National Pipe Tread).
More on NPT at:
http://en.wikipedia.org/wiki/National_pipe_thread
Jim
I will take back what i said above , mine were 1/8" but i drilled them and re-tapped for 1/4", they drain faster and have a full opening petcock. I looked at them and it made me remember what i had done. It's he** getting old.
Rick
If you had a 1/4" pipe thread in your water outlet, the petcock would almost fall through the hole!
NPT =
National
Pipe
Tapered
NOT Thread or Tread (sic).
Thanks for the threading info. My situation is that I noticed the petcock on the radiator was missing and would like to replace with something so I can run the vehicle until I can order the correct part in. Can anyone suggest what size bolt & thread (fine/coarse) could be used in the mean time?
I stock some 1/16" NPT brass fittings. Does any one else on here know where they are used?
Ralph, you don't want a bolt of any kind. Go to the plumbing department and get a 1/8" plug. It's a pipe thread.
Do NOT use a bolt to fill the hole. You'll ruin the threads in the radiator. They are TAPERED threads. Go to the hardware store and buy a 25 cent 1/4" NPT PLUG and use that.
Ops, make that 1/8" NPT Plug.
Ok, thanks ...I'll pick one up while I'm waiting for the correct petcock to arrive.
Ralph,
You might want to get a roll of pipe thread tape to help seal the joint. Also helps when you take it out.
Oh, yes, There is also NPS for National Pipe Straight Thread. This table gives a list of possible standards to choose from.
Some years ago, while on a run, I realized water was streaming out from the bottom of the radiator. (An advantage to a fenderless speedster, I could see it.) I pulled over, the car had not begun to overheat. I discovered that the petcock had fallen out. Water was nearby. So I swiped a grease fitting from the steering base bracket (I often use early after-market type grease fittings instead of the grease cups Ford supplied) and put it in place of the missing petcock. It didn't leak. I had lost about half my water. Refilled the radiator slowly and went on my way. It was a couple months before I replaced the petcock.
A common size modern Zerk fitting should work just as well. Most of them are standard 1/8 inch pipe thread.
Also, some hardware stores still carry decent looking petcocks or shutoff valves in a variety of tubing and pipe threads. Make sure it is the proper thread, 1/8 inch pipe.
Some confusion over 1/8 inch vs 1/4 inch is simply that tubing and pipe are measured by an archaic internal size measurement that has been translated to a defined outside thread. This defined pipe thread has been around for well over a hundred years.
Drive carefully, and enjoy, W2
It is indeed confusing as schedule 40 1/8" pipe measures just over 1/4" inside.