More oil pickup issues don't know what to do

[Frankb]

I had a hell of a time removing old pickup from 440. Finally got it out yesterday and went to install new pickup from 440 source (part # 121-1056). Now the issue is I don't think the the threads on new pickup are NPT. They are are different from the pickup that came out of the engine. A Milodon pickup was removed from the engine. When I installed the new pickup it screwed into the block just fine but there were not enough threads on it to position it properly. It needed an additional 1/2 a turn. So I bought a 1/2 inch NPT die and I figured to add a thread or two so as to get pickup properly positioned. Die did not fit properly. That's when I looked closer and saw the threads on new pickup are different than old pickup. So what is the right thing to do to remedy this? Why would a straight thread pickup screw into an NPT hole? I see two possibilities: cut the new pickup to NPT (can that even be done) or order a different pickup with NPT threads. The old pickup that came out of engine is top in pic. Block was modified to accept 1/2 inch pickup.

 

[pnora]

The top ones look correct. The bottom one looks close but more the CCJ. Cheap Chinese Junk.

 

[sc440]

Do you have dial calipers? If so measure for taper the top pic old one looks like the correct npt. See if the source one is tapered it doesn’t look like it from the photo also did you line up the 2 pickup threads to compare the treads per inch? I would probably contact 440 source and see what they say think I would run a milodon one and check depth to pan bottom

 

[BSB67]

Did you run out of threads on the pick up, or did the pick up get too tight before you could get into position?

The straight thread will seal fine. Just figure out the best way to get the pick up orientation correct.

 

[BSB67]

The factory pick up was a straight thread.

 

[Fran Blacker]

Top one looks like NPT. Bottom NPS. nps thread dimensions - Google Search

 

[sc440]

The tapered and straight 1/2” are both 14 threads per inch not sure what the block was taped with both should thread in but if hole is taped with npt it would only fit good at the end of the threads

 

[sc440]

Stock 440 was 3/8 so it was definitely modified. Can’t remember what I tapped mine with I used a milodon hemi pickup but had to cut and reweld it to get the depth right.

 

[pnora]

The factory pick up was a straight thread.

Really????

 

[Geoff 2]

NPT threads. The female thread is parallel. The male section is tapered.

The thread on the bottom p/up in the pic is definitely not tapered.

You could cut off the end of the tapered thread p/up & weld it onto the other p/up.

 

[Geoff 2]

For piece of mind, weld a sleeve over the join.

 

[BSB67]

The factory pick up was a straight thread.

For those that do not believe this, go and measure the root diameter of a factory, or an old factory replacement pick up. Then either pull out a machinist hand book or measure an actual 3/8, or 1/2” NPT.

The hemi 1/2” pick up use to state NPS in the specification.

All the performance aftermarket pick ups I’ve seen do have an NPT. They all will seal, but the NPT is more likely to crack the block if you really torque it if the casting is thin.

 

[lewtot184]

The factory pick up was a straight thread.

this is correct. don't use a NPT tap to clean the block up. use only a NPTS. straight pipe threads have the same pitch as taper but a much shallower taper angle. if all you need is a half or full thread try gradually removing a little of the pick-up's thread end until you get a good fit. hopefully the block wasn't tapped for taper threads.

 

[dvw]

NPS is said to need a O ring to seal. So if the factory thread was NPS and not NPT why was there no O-ring?
Doug

 

[lewtot184]

NPS is said to need a O ring to seal. So if the factory thread was NPS and not NPT why was there no O-ring?
Doug

i've never heard of any pipe thread needing an o-ring. if they need an o-ring then way the tapered thread? a machine thread may need an o-ring/gasket because it's not interference and can't by itself seal.

 

[BSB67]

NPS is said to need a O ring to seal. So if the factory thread was NPS and not NPT why was there no O-ring?
Doug

Obviously you would not use a straight pipe thread on a 300 psi hydraulic system. There are likely few situations where you would or could use a straight pipe thread for sealing, and nobody in the pipe thread sealing business would publically recomment it. But the factory did, and apparently it works. The dP on that joint is incredibly small.

Melling states that their replacement pick-up has a NPSM thread. But that's from the internt.

Not that real life experiences matter on these threads to many posters, most of the motors I've done the pick-up has a straight pipe thread. Why? because when I measure them, that is what they are.

 

[lewtot184]

it's my understanding that straight pipe thread is used in machinery. taper pipe thread is a utility thread.

 

[Frankb]

Did you run out of threads on the pick up, or did the pick up get too tight before you could get into position?

The straight thread will seal fine. Just figure out the best way to get the pick up orientation correct.

Ran out of threads

 

[451Mopar]

On the block, I use a NPT taper reamer before trying to tap the hole. (easier to tap a tapered hole for NPT.)
I have a NPT die to go over the pickup threads too.
On the 400 block 500" stroker, I ended up making the pickup because of the BCR main cap and girdle kit.

 

[BSB67]

Ran out of threads

First you should mock up everything to make sure you have the pickup to oil pan clearance you want knowing you’ll be going a little deeper.

Your pictures from both of your threads show that the machine shop ran the 1/2” NPT tap deep into the block. You can:

1) drill, ream, remove the first 2 or 3 threads from the block to allow the new pickup to tighten up in the bottom of the taper, or

2) get a NPS die and extend the PU threads, or

3) Get a NPT die and extend the PU threads.

Any of these will work. If the PU is to far from the oil pan, you’ll need to go to plan B