Rear Main Oil Return Tube

[FlatheadEric]

37-39 engines - Rear main bearing cap oil return tube
I think I read somewhere on here that the tube is 1/2" OD and the thread is 32 tpi. Can't find the post any more.
Can someone tell me the correct name and size of the thread?

Thank you

[51 MERC-CT]

Originally Posted by FlatheadEric

37-39 engines - Rear main bearing cap oil return tube
I think I read somewhere on here that the tube is 1/2" OD and the thread is 32 tpi. Can't find the post any more.
Can someone tell me the correct name and size of the thread?

Thank you

Check here for some info as well as a source for a tube.


https://www.fordbarn.com/forum/showt...il+return+tube


https://www.fordbarn.com/forum/showt...il+return+tube

[Zeke3]

Here is another link with discussion of the rear main oil drain tube. I will check my main cap again to see what the thread pitch is.

https://www.fordbarn.com/forum/showthread.php?t=285162

[FlatheadEric]

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Thanks for responding guys.
Zeke3 - That is the old post I was vaguely recalling. Based on your comments in the original post,
"I checked the rear main cap from my 1937 21 stud engine and the thread is much finer than a 1/4" npt, which has 18 tpi. I think it may be 28 tpi and a 15/32" drill bit fits in the hole, 0.469 in. diameter."
I have found what I think is the thread information. I hadn't heard of UNEF until now.