Drain line off of 475?

[mackthehack]

I Have most of my parts to do my 475 over stock. For my drain line, I'm going to the valve cover. I have -10AN drain line with fittings. One fitting goes from -10AN to a 3/8 NPT. I have looked all over to find the correct size drill bit and tap. It seemed that a 5/8 drill bit will work. But not sure for the tap. The threads on the fitting seem to be metric 1.5. Diameter looks to be a 16 in metric.

What size drill bit and tap should I use?

Thanks in advanced for help.

 

[PureHybrid]

What are you trying to tap, the valve cover? Sounds like the fitting may be an oring straight thread to -10, its a common style. My tap chart shows a 3/8-18 NPT using a 37/64 drill bit.

 

[BLKLMM]

I would drain to oil pan:thumb:

 

[Janimal444]

I'm confused, is the fitting you are threading in a 3/8" NPT fitting? If so, then you will need a 3/8" pipe tap. This uses a 9/16" drill bit.

 

[JoshH]

You will need a 3/8 NPT tap if you are trying to thread the 3/8 NPT part of the fitting into the valve cover. I think the drill bit is 37/64".

 

[jmaz268]

edit: misread

 

[Janimal444]

I would drain to oil pan:thumb:

X2, that's where I ran mine. Although mine is leaking like a sieve at the moment, so I guess I'm not one to talk

 

[mackthehack]

What are you trying to tap, the valve cover? Sounds like the fitting may be an oring straight thread to -10, its a common style.

Trying to tap the valve cover. Maybe I have it wrong. I don't recall which one was the tap and which one was the die. I wan to drill and thread the valve cover. Yeah, the fitting is a -10 to 3/8 adapter. (What its labeled)

 

[Operator1]

I Have most of my parts to do my 475 over stock. For my drain line, I'm going to the valve cover. I have -10AN drain line with fittings. One fitting goes from -10AN to a 3/8 NPT. I have looked all over to find the correct size drill bit and tap. It seemed that a 5/8 drill bit will work. But not sure for the tap. The threads on the fitting seem to be metric 1.5. Diameter looks to be a 16 in metric.

What size drill bit and tap should I use?

Thanks in advanced for help.

If the fitting is -10 to 3/8 NPT, then you need a 3/8 NPT tap and iirc that takes a 9/16 drill.

 

[mackthehack]

Thought about going into the pan, but don't want to worry about messing up. And pulling the pan.

For the bit. I wasn't sure. Because of how the fitting is labeled for the size. Then I checked drill bit sizes and it's about the size of 5/8. Checked the threads they are fine pitch. Standard size didn't really seat to well. The metric size 1.50 thread pitch seated perfectly.
That's why I was unsure and thought I would ask.

 

[mackthehack]

Thank you gents...

 

[dmax711]

What are you trying to tap, the valve cover? Sounds like the fitting may be an oring straight thread to -10, its a common style. My tap chart shows a 3/8-18 NPT using a 37/64 drill bit.

x2 37/64" would be ideal but 9/16 will work

 

[mackthehack]

I know I am probably confusing everyone and myself. Just rechecked the adapter package. It says -10 to 3/8. I double checked the fitting to my 9/16 tap. The tap is way too small. I measured the end of the fitting which is supposed to be 3/8 NPT. It measures out a just under 5/8 diameter.

Maybe I'm over thinking this shit. But thanks again for the replies.

 

[Operator1]

NPT threads go by the size of the hole in the fitting, not the size of the threads. The threads are tapered, so they will tighten and seal. 3/8 NPT Is the tap you need.
I have the same fitting in my valve cover. Make sure you get it in the right spot.

 

[Janimal444]

I know I am probably confusing everyone and myself. Just rechecked the adapter package. It says -10 to 3/8. I double checked the fitting to my 9/16 tap. The tap is way too small. I measured the end of the fitting which is supposed to be 3/8 NPT. It measures out a just under 5/8 diameter.

Maybe I'm over thinking this shit. But thanks again for the replies.

That makes sense actually, the fitting as measured on the outside of the threads would actually be a little larger than half an inch.

You need a 9/16" drill bit, then a 3/8" NPT tap. The NPT tap that large will be hard to find, try a plumbing or industrial supply house. If no luck then look online.

Find a spare piece of aluminum lying around if you have one and practice on that first. I say aluminum because it will be a lot easier than practicing on steel.

P.S. Note that an NPT tap is tapered. When you are practicing, get a good idea of how deep you want to go with the tap. If you go too deep, since it is tapered, it will not seal properly when you thread in the fitting.

 

[mackthehack]

Thanks for the info and tips guys. I will look around online for a tap that size. And I will practice before I commit to drilling on my valve cover.

Operator1. Do you have pictures of where you went on the v/c?

 

[PureHybrid]

3/8NPT taps are fairly common, Fastenal / lowes / sears should have them.

 

[Operator1]

Click here and go to post #10 in that thread. That's what I followed.

 

[mackthehack]

thanks man

 

[Harbin_22]

Are you going to remove the valve cover to drill it?