E-Bodies.org Cuda Challenger Forum

Technical Shop => Engine, Transmission & Rear End => Topic started by: kawahonda on October 03, 2019, 08:11:46 AM

Title: Need intake coolant fitting
Post by: kawahonda on October 03, 2019, 08:11:46 AM
I'm having a hard time finding a straight heater hose coolant fitting for my LD340. It does not use 1/2" NPT, but rather what seems 5/8" NPT.

Please don't tag anyone. I've already "tried" one venue.
Title: Re: Need intake coolant fitting
Post by: Bullitt- on October 03, 2019, 08:25:38 AM
 :waving:   doesn't give thread size...

https://www.manciniracing.com/hehonib.html
Title: Re: Need intake coolant fitting
Post by: Burdar on October 03, 2019, 08:58:45 AM
Have you tried the HELP line of parts at your local parts store?
Title: Re: Need intake coolant fitting
Post by: kawahonda on October 03, 2019, 09:04:28 AM
I haven't gone into part stores yet but I've been searching the web quite a bit!
Title: Re: Need intake coolant fitting
Post by: DeathProofCuda on October 03, 2019, 09:08:30 AM
Quote from: Bullitt- on October 03, 2019, 08:25:38 AM
:waving:   doesn't give thread size...

https://www.manciniracing.com/hehonib.html

The big block fitting sets shown in the Mancini link look like they include a 5/8" threaded fitting.  I think I have a spare one in the garage somewhere that I can check.
Title: Re: Need intake coolant fitting
Post by: gzig5 on October 03, 2019, 11:03:25 AM
The OEM fitting heater hose fitting I bought was one size too small for the LD4B intake so I just picked up a brass reducing bushing at the hardware store and got on with life.
Title: Re: Need intake coolant fitting
Post by: kawahonda on October 03, 2019, 11:08:40 AM
Yea. It will all get sprayed orange anyways. Sounds like I may need a reducer.

I'm pretty sure there has to be a 5/8" NPT 1/2" Hose barb slotted fitting out there. I think just jollying around to part stores is going to create a lot of time burn.
Title: Re: Need intake coolant fitting
Post by: Brads70 on October 03, 2019, 12:27:20 PM
No such thing (that I know of?)  as a 5/8 NPT thread.  likely 3/8 OR 1/2 NPT
5/8" is referring to the heater hose size
Title: Re: Need intake coolant fitting
Post by: kawahonda on October 03, 2019, 01:09:40 PM
The LD340 does not have a 1/2 NPT header hose connection. A 1/2 NPT falls through the hole.....

Whatever the "long" one in this kit is (I believe 1/2" NPT) falls in the hole:

https://www.manciniracing.com/19ahehonikit.html

But I do agree that there appears to be "no such thing" based on how much I've looked!
Title: Re: Need intake coolant fitting
Post by: DeathProofCuda on October 03, 2019, 02:05:52 PM
What is the diameter at the face of the threads for the fitting that will fall through the hole?

What is the internal diameter of the hole?

A 1/2" NPT fitting is right about 3/4" at the face of the threads.  Overall diameter is listed as 0.840"
Title: Re: Need intake coolant fitting
Post by: Brads70 on October 03, 2019, 02:09:01 PM
Quote from: kawahonda on October 03, 2019, 01:09:40 PM
The LD340 does not have a 1/2 NPT header hose connection. A 1/2 NPT falls through the hole.....

Whatever the "long" one in this kit is (I believe 1/2" NPT) falls in the hole:

https://www.manciniracing.com/19ahehonikit.html

But I do agree that there appears to be "no such thing" based on how much I've looked!

Tap drill size
for 3/8 NPT is 9/16 or .562 
for 1/2" NPT is 45/64 or .703"
for 3/4 NPT is  29/32 or .906

Are you sure 1/2 NPT falls in?  :o
Title: Re: Need intake coolant fitting
Post by: kawahonda on October 03, 2019, 04:00:24 PM
I can't find the fitting (It will pop up I'm sure), but the intake fitting bore measures .588"

I have a freeze plug fitting that threads perfectly in it, and it measures. .666"
Title: Re: Need intake coolant fitting
Post by: Brads70 on October 03, 2019, 04:39:19 PM
Quote from: kawahonda on October 03, 2019, 04:00:24 PM
I can't find the fitting (It will pop up I'm sure), but the intake fitting bore measures .588"

I have a freeze plug fitting that threads perfectly in it, and it measures. .666"

So if I'm understanding this right , its 3/8 NPT . It's a tapered pipe tap so it gets bigger at the opening of the hole , as you tap the tap drill sized hole the tap cuts on a tapper making the opening bigger than the tap drill size.
Title: Re: Need intake coolant fitting
Post by: DeathProofCuda on October 03, 2019, 07:04:16 PM
 :iagree:

Here is a photo of a big block set. 

The smaller one shown at the top is 1/4" NPT.  It is shown next to a 1/4" NPT air fitting.  Outside thread diameter is 0.54"

The larger one is 3/8" NPT.  It is shown next to a 3/8" NPT tap.  Outside thread diameter measures 0.66" with my caliper.

The large tap at the bottom is 1/2" NPT.  Outside thread diameter is 0.84"
Title: Re: Need intake coolant fitting
Post by: kawahonda on October 03, 2019, 08:33:10 PM
This is awesome.

So basically, 3/8" does not mean .375. 1/2" does not mean .50. I still don't understand that, but whatever. It must have something to do with the tapering, but I'll have to wrap my mind around it tomorrow.

Somehow, it seems that I need a 3/8" NPT according to this!

I bet if I found my fitting, it would be 1/4" NPT, which is .54". That's what it "falls into" the ".588" bore.

A 3/8" NPT slot fitting for a 1/2" hose should be easier to find, I would assume?

Probably this is what I need: https://www.summitracing.com/parts/fss-84712/overview/

Deathproof, does that hose end accept a 1/2" hose?

Title: Re: Need intake coolant fitting
Post by: DeathProofCuda on October 03, 2019, 09:32:43 PM
NPT fittings can be a bit confusing.  You have to remember that the sizes are based on pipe sizes and that pipe sizes are specified by their inner diameter, not their outer diameter.  That's how you get a 1/2" pipe that has an OD of 0.84".

For the fittings in my photo, the 1/4" NPT one is sized for a 1/2" (ID) heater hose.  The 3/8" NPT fitting is sized for a 5/8" ID hose.

Seems like the fitting you found at Summit would be the ticket :bradsthumb:
Title: Re: Need intake coolant fitting
Post by: Burdar on October 04, 2019, 06:21:44 AM
The factory fitting from my Challenger is in the middle.  Is this what you need?  I got a replacement at my local parts store.  It doesn't look the same but it works.  After I bought the replacement, I found out that Mega Parts sells the factory correct part.  I think it's 5/8 pipe thread and reduces to fit a 1/2" heater hose.  The fitting on the left in the picture is out of the HELP line at the parts store.

Edit:  Yep, here it is.  You can get a replacement that reduces to 1/2" at your local parts store but I don't have the part # any more.  The reducer fitting isn't in the HELP line.
http://www.megapartsusa.com/proddetail.asp?prod=132%2DHC010

(https://i.postimg.cc/cLBhYHt3/51112001-zps4c81bfab.jpg) (https://postimages.org/)
Title: Re: Need intake coolant fitting
Post by: kawahonda on October 04, 2019, 09:00:35 AM
Wow...I am shocked you found a 5/8 NPT fitting. Not only that, but you found one that is slotted and that looks stock.

It sounds like I'm actually a 3/8" NPT because I didn't understand NPT pipe threading, and still don't. LOL

Hopefully this thread will help others in the future.

For reference, the LD340 uses 3/8" NPT for the bypass.

What's included in the small block 340 kit from the venders is probably a 1/4" NPT. I cannot tell you if that is stock or not, but it doesn't fit the LD340.
Title: Re: Need intake coolant fitting
Post by: DeathProofCuda on October 04, 2019, 09:06:41 AM
The fitting that Burdar linked is not 5/8 NPT.  There is no such thing.  NPT fittings jump from 1/2" to 3/4".  As the link states, it is 5/8" hole size, which means it is actually 3/8" NPT.  Yes, it is confusing. 

Bottom line is that either the part you found at Summit or the one that Burdar linked looks like it should work for you.

Here is a link to a chart showing NPT pipe sizes:

https://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html
Title: Re: Need intake coolant fitting
Post by: 73440 on October 04, 2019, 12:57:06 PM
Quote from @DeathProofCuda (https://forum.e-bodies.org/mlist/deathproofcuda_4918) ,  Here is a link to a chart showing NPT pipe sizes:

https://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html

@DeathProofCuda (https://forum.e-bodies.org/mlist/deathproofcuda_4918) , that's a good website, used before , lotta info.
Title: Re: Need intake coolant fitting
Post by: YellowThumper on October 04, 2019, 03:25:40 PM
NPT (National pipe taper) diameter callouts are for the ID. Not the thread. That would be huge. IIRC they should be 3/8 NPT into manifold. Thread od will be around 5/8 or so. This fitting can then have the 1/2 or even 5/8 OD barb to hold 1/2 or 5/8 ID heater hose.

-edit- lol I now read the previous same answers after I wrote reply
Title: Re: Need intake coolant fitting
Post by: DeathProofCuda on October 04, 2019, 03:58:31 PM
Quote from: YellowThumper on October 04, 2019, 03:25:40 PM
NPT (National pipe taper) diameter callouts are for the ID. Not the thread. That would be huge. IIRC they should be 3/8 NPT into manifold. Thread od will be around 5/8 or so. This fitting can then have the 1/2 or even 5/8 OD barb to hold 1/2 or 5/8 ID heater hose.

-edit- lol I now read the previous same answers after I wrote reply

Hey, at least we're all on the same page now!  :ohyeah: