What is the TPI of a 440 Oil Pickup?

[moparedtn]

If it had straight threads, basically, it would never tighten up.... unless it had a shoulder and a gasket. Or bottomed out in the threads. And them we couldn't get the pickup turned where we need it in the bottom of the pan.

Yes sir, Professor Rick. Y'all are doing this old sprinkler pipefitter proud with all this information on NPT!
I got all that stuff beat into my young skull decades ago by huge old foremen and it never leaves you.

 

[lewtot184]

All pipe threads in our Mopar blocks are NPT. (Tapered.) Not NPS (Straight.)

Factory is straight pipe thread not the plumbing tapered.

 

[padam]

Does this look like npt?

 

[rickseeman]

It's a Milodon oil pickup for a wedge Mopar. So it's 3/8" NPT. If you measure it you will find the threads are a larger diameter at the top than the bottom.

 

[padam]

It's a Milodon oil pickup for a wedge Mopar. So it's 3/8" NPT. If you measure it you will find the threads are a larger diameter at the top than the bottom.

Yes its a Milodon. I think when I got mine it measured straight. definately not like NPT.

 

[rickseeman]

Straight pipe threads are so rare that most times people would just say 3/8" pipe. Because "pipe" automatically means tapered threads. In 50+ years of working on stuff I might have seen straight pipe threads once. The only oil pickup I have here is for a Hemi. The bottom of the threads are .802" and the top is .822"

 

[padam]

The pictures below are of the factory pickup tube from my 1964 V41 413, which I am pretty sure came out of a passenger car.

The threaded portion is bent a little, so maybe why the end checks a little bigger.

But clearly this isn’t NPT.

I will take it to work tomorrow and check the thread pitch diameter with actual thread mics.

 

[R/T Boy 67]

The threads on the pickup can be straight. It will tighten up if screwed into a tapered thread. The end will squeeze in a little when tightened.

 

[padam]

The threads on the pickup can be straight. It will tighten up if screwed into a tapered thread. The end will squeeze in a little when tightened.

That may be, but not really how an NPT fitting is supposed to work.

 

[R/T Boy 67]

I know how a pipe thread works, but the pickup above is a straight thread, and I have seen other factory pickups that are straight also.

 

[BSB67]

I wish i knew where I posted it, cause I went through this a couple years ago.
I installed a Miladon pan and pickup and I’m pretty sure the pickup had straight threads.

The original pick-ups have straight pipe threads.

 

[BSB67]

The pictures below are of the factory pickup tube from my 1964 V41 413, which I am pretty sure came out of a passenger car.

The threaded portion is bent a little, so maybe why the end checks a little bigger.

But clearly this isn’t NPT.

I will take it to work tomorrow and check the thread pitch diameter with actual thread mics.



View attachment 1703196View attachment 1703197View attachment 1703198View attachment 1703199View attachment 1703200

This is correct. The straight pipe thread will measure a very slight taper. Far less than the standard NTP taper. They thread up with each other as well.

 

[BSB67]

Looks like Melling has it wrong. They list it as NPSM thread.

Melling 63-S3 Melling Oil Pump Screen Assemblies | Summit Racing

 

[padam]

The threads on the pickup can be straight. It will tighten up if screwed into a tapered thread. The end will squeeze in a little when tightened.

Looks like this is the case.

I measured the threads on my factory pickup. The pitch diameter checks at about .618 at the straight section and .613 at the open end. This is undersized to the NPSM spec of .621 min. This could be by design from Mopar, maybe sort of a bastard size.

I screwed it into a 3/8 npt fitting and it goes in about 6 threads before tightening up.

It maybe also why I had an issue with the Milodon pickup. I wish I could remember the details, but I know I had to try run a tap in the hole in the block to get it in. If the aftermarket pickups are made to NPSM specifications they may be oversized to the tapped hole.

 

[Krooser]

Ahhh, a teaching moment! Congrats to all of you who actually posted a correct, easy to understand answer to the OP's question. I was waiting for a wise*ss answer but it never came. Maybe we all are maturing? Naw...

Sorry....I didn't see this post early enough to contribute a smart *** comment.

I'll try harder next time!!!

 

[Krooser]

The oil pump pickup tube uses a NPSM thread not NPT.

I wondered why the oil pickup tube in my 318 pump would not tighten. I was going to use some Teflon tape to try to get it to quit swinging then decided to do some research.

I always thought it was NPT...it ain't.

This thread is used in hydraulic systems where there is little chance of pressure loss at the threads...from what I read.

Google NPSM...bingo

 

[padam]

The oil pump pickup tube uses a NPSM thread not NPT.

I wondered why the oil pickup tube in my 318 pump would not tighten. I was going to use some Teflon tape to try to get it to quit swinging then decided to do some research.

I always thought it was NPT...it ain't.

This thread is used in hydraulic systems where there is little chance of pressure loss at the threads...from what I read.

Google NPSM...bingo

Well, its used for systems with low or no pressure.