Kooks EGR fitting

XR7-4.6

XR7-4.6

Administrator
Staff member
Joined
Sep 12, 2023
Messages
3,759
Location
Roselle, IL
Vehicle Details
1994 Cougar XR7 DOHC TR3650
Country flag
So I’ve run into a bit of a snag. I’m to be running 4V Kooks headers and don’t have much choice but to delete EGR unless I come up with a custom tube to fit my combo. I bought a block off set this week but the cap for the header is way way to small for the kooks, it fits my existing manifolds fine so it seems the marks use a much larger nut/tube?

I tried seeing if a 3/4” plumbing cap might fit but it’s just on the cusp of too small as well. Anyone else with 4V headers run into this, solutions? Only thing I can come up with is find a used EGR tube to salvage the nut from and weld it closed but finding one is it’s own challenge these days.

IMG_6679.jpegIMG_6680.jpeg
 
XR7-4.6 said:
I tried seeing if a 3/4” plumbing cap might fit but it’s just on the cusp of too small as well.
Click to expand...

Any chance it's a metric thread ? 🤔

If you can get the first couple threads to take its just going to be a mechanical seal anyways.
 
dDUBb said:
Any chance it's a metric thread ? 🤔

If you can get the first couple threads to take its just going to be a mechanical seal anyways.
Click to expand...

I was wondering if it might be metric but measuring/counting the threads it sure seems like it’s 3/4 x 14 like the pipe cap, but I can’t even get it to catch

IMG_6681.jpegIMG_6683.jpeg

(Last pic was .5” on the calipers)
 
So after using my triangle file to clean up the end threads a bit I was able to get the cap started, but this is about as far on as it goes, seems like about two threads. Mechanical seal it is!

IMG_6684.jpeg
 
The EGR tube fitting should be the same as any other ford of the era. I have an old 95 2V tube here I can send with the steering shaft if you want to weld it closed. I've hung onto a few of the old 95 tubes for an occasion such as this.
 
supergordo said:
The EGR tube fitting should be the same as any other ford of the era. I have an old 95 2V tube here I can send with the steering shaft if you want to weld it closed. I've hung onto a few of the old 95 tubes for an occasion such as this.
Click to expand...

It's definitely not. I threaded the blockoff I ordered(pictured in the first post) onto both my Cobra manifold as well as the stock 94-97 manifolds from my car and it fits perfectly well, same as the EGR tubes. These 4V Kooks and I presume Mark VIII manifolds for some unknown reason use this larger fitting which in my guesstimation is at least 1/8"-1/4" bigger
 
dDUBb said:
If you want to seal it 100%; use some X-pando pipe joint compound .. it's what I use on threaded joints for high pressure steam systems. 😉
Click to expand...

I think that's exactly what ill do! I'd like to pick up another cap to see if this one is cut weird and/or heat it up to see if I can get a few more threads engaged but I think this will work. Just like spending $10 on feeler gauges to shim my $1,700 cams, I'll be spending $20 in plumbing caps and goop to seal these $1,000 headers lol
 
I have NPT pipe caps and some xpando I could send you. Spending $15 on a can of compound to make 1 joint seems like a waste. I'm just thinking its a metric thread ( the Mark manifold uses a thread to thread adapter on the EGR )
 
In the past i have used a stock nut with a penny installed to block it off. Works great and only costs a penny. Or a penny-sized piece of steel might last longer
 
Last edited:
Typically this would have been a flared nut for tubing ( egr ) .. determined by the OD size of the pipe itself. Maybe SAE threads .. not the same as NPT.
 
Questions: Are the threads on a taper?
What is the od?
What is the thread to thread spacing?

The fittings on the trans are bpst, british pipe straight threads. There is also npst, national pipe straight threads.npt is national pipe taper. AN is a straight thread, english based. All are different.
 
Grog6 said:
Questions: Are the threads on a taper?
What is the od?
What is the thread to thread spacing?

The fittings on the trans are bpst, british pipe straight threads. There is also npst, national pipe straight threads.npt is national pipe taper. AN is a straight thread, english based. All are different.
Click to expand...

1.05” od, threads are 14tpi(I measured 7 in a half inch). That’s why I thought the plumbing cap would fit.

Are these caps ever tapered npt? it’s possible I just bought the wrong one but there’s nothing on the packaging that says it

IMG_6685.jpeg
 
Last edited:
dDUBb said:
I have NPT pipe caps and some xpando I could send you. Spending $15 on a can of compound to make 1 joint seems like a waste. I'm just thinking its a metric thread ( the Mark manifold uses a thread to thread adapter on the EGR )
Click to expand...

I forgot to ask is that compound hard to remove later on? Right now I don’t have the time, fab skill or patience to do it but down the road I would ultimately like to cobble together an EGR tube
 
I can tell just from looking at the picture that those aren’t the same thread. That cap most likely is tapered pipe thread, and the thread on the header will not be tapered. 1”x14 is a standard thread pitch, so I would buy a 1”x14 nut, weld a plate over the end, and just tighten that down on the bung.
 
cap you have is tapered, fitting is straight, cap is expecting the end to be smaller. it's npst

Take it outside and try the hose. thats .75 straight

A stainless dishwasher hookup would work,
 
Last edited:
XR7-4.6 said:
I forgot to ask is that compound hard to remove later on? Right now I don’t have the time, fab skill or patience to do it but down the road I would ultimately like to cobble together an EGR tube
Click to expand...

Yeah it's hard to remove, not permanent. It takes a bit of effort to get it to unthread if it's going to be in vehicle later .. 🤔
 
A stainless dishwasher hookup would work, but you'd have to yank the rubber seals
 
www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com
 
You must log in or register to reply here.

Similar threads

Back
Top