Stripped Bung

[cody]

Wow, the only thing cheaper than buying that set would be borrowing it.



Can I stop by after work?

[Dean]

Sure

[Kevin M]

Taps and Dies are one of those things where the cheap stuff isn't as good as the good stuff. I'd spend the $30 if I were in your spot Cody.

[cody]

Hmm. Dean, do you feel confident that the taps in that set are good enough to get the job done.? I don't think either of us want me to ruin one of your taps. I'll be stuck and feel like I need to buy you a replacement which will cost more than the entire set.

Hmmm, but I don't want to be caught agreeing with Kevin.

[ScottyS]

The Harbour Freight NPT tap worked fine for my EGT install in OEM headers, FWIW.

[cody]

And that's a finer thread than the thead of the tap I'll end up using so it should really be fine. I even have cutting oil.

[cody]

Originally Posted by Dean

Sure

Let's put this plan on hold for now, please. My co-worker thinks he has a tap set at home. He's going to check and bring it in tomorrow if he can find it.

[knucklesplitter]

90+% sure the correct tap size is 1/8"-NPT (or 1/8"-BSPT - "metric" version with same thread pitch but different thread angle).

90+% sure I have a machine-shop quality tap if you need one.

90+% sure that nobody can be 100% sure of anything (at least not without walking down to the garage and digging to find out).

[cody]

Ha!

Thanks but I already have the tap that's the correct size for the probe, but the hole is stripped completely. All I need is a tap for an appropriately larger size hole and a very short bolt that matches the tap, a washer maybe (?), and the right drill bit, which I may have.

I'm going to take the original tap to R&E tomorrow at lunch tomorrow. The guy I spoke to said he could use it to determine the best diameter of bolt and sell it and the tap to me. Hopefully I'll have the tap from my co-worker by then as well as the right drill bit at home already.

[cody]

Alright, I think R&E set me up right with a short grade 8 bolt (1" long I think), a grade 8 washer (to hopefully help seal the bolt head to the header, and a nut to re-true the theads after I shorten the bolt to about 1/2". I would have preferred to stick with pipe thread, but he didn't have pipe thread plugs in an apropriately larger size in grade 8.

I have the correct size tap thanks to my coworker (and it's Craftsman so I don't have to worry if I damage it). The drill bit I have is a 1/64th of an inch too narrow, but I think that's fine.

Anyone see any issue with any of this before I go at it?

Thanks to the 3 of you that offered me taps.

[Kevin M]

Sounds like a good plan. I would measure the depth of the hole before cutting down the bolt though- no sense leaving it longer or shorter than the material you're filling.

[cody]

Good point. I'll error on the side of too long but try to get it flush. I honestly doubt that half an inch of bolt sticking out would cause more resistance than the probe that's currently sticking more than halfway through the pipe (though much thinner than the bolt) but I definitely want to cut the bolt shorter just to keep efficiency as high as possible.

[sperry]

I would have just gotten it welded. I've had both a hole welded shut and a bung welded on the stock cast headers, and never had an issue, nor did the welder complain about doing the job. Had it done years ago at the muffler shop next door to Indy Auto (I think that's McVay's?).

It probably would have cost you less than the price of that nut and bolt to get the hole closed, and it would have been less work just to take the header off and bring it to the shop than all the non-sense w/ cutting bolts, tapping holes, trying to get a washer to seal, etc.

[cody]

Well, the bolt, washer and nut came to a whopping $3.22.

I'm certainly open to suggestions. I just called Alex's friend Ansel since he's an acomplished welder and he said he'd just do exactly what I'm doing, though Alex and I think he was probably just trying to avoid me asking him to weld it for free (), which wouldn't have happened.

I'd honestly rather get it welded so I don't have to worry about the bolt coming loose or me re-stripping the new larger hole. I'll call McVay's if I can find them.

[sperry]

My big concern is that w/o NPT threading, you're never going to get that bolt tight enough in the hand-tapped threaded cast iron to have a washer seal from exhaust leaks. Even if you do get it tight initially, the expansion difference between cast iron and grade 8 stainless will eventually loosen that bolt.

There's a real reason EGT probes use pipe-thread. I'd pay the $15 or whatever it costs to get the hole welded... actually, I'd pay the $25 or whatever to get a real bung welded on there and then just put the correct plug in the hole if I wasn't running the EGT sensor and leave myself the option of putting an EGT in there painlessly in the future.

[cody]

Just spoke to Rusty at C&C and he said he doesn't know anyone who can weld cast iron but he said they tap and plug manifolds with bolts all day long. I think it'll be fine. It's not like the car's going to explode if the bolt backs out or starts leaking. I can check it without pulling the heat shield off too since there's a hole in the heat shield for the probe wire.

[cody]

Originally Posted by sperry

My big concern is that w/o NPT threading, you're never going to get that bolt tight enough in the hand-tapped threaded cast iron to have a washer seal from exhaust leaks. Even if you do get it tight initially, the expansion difference between cast iron and grade 8 stainless will eventually loosen that bolt.

There's a real reason EGT probes use pipe-thread. I'd pay the $15 or whatever it costs to get the hole welded... actually, I'd pay the $25 or whatever to get a real bung welded on there and then just put the correct plug in the hole if I wasn't running the EGT sensor and leave myself the option of putting an EGT in there painlessly in the future.

It's on the wrong manifold so I want to plug it permantently for sure. Maybe I should have gone with the next size NPT and a plug but the plug was an unspecified metal and the only metal I know gets used with exhaust manifold heat is grade 8.

[sperry]

Originally Posted by cody

Just spoke to Rusty at C&C and he said he doesn't know anyone who can weld cast iron but he said they tap and plug manifolds with bolts all day long. I think it'll be fine. It's not like the car's going to explode if the bolt backs out or starts leaking. I can check it without pulling the heat shield off too since there's a hole in the heat shield for the probe wire.

Hrm... I never thought cast iron was that bad to weld that "nobody" in Reno can do it.

Also, I doubt that Rusty's plugging headers that see 1750 deg F temps and pressures like our turbo headers see. On a N/A motor, a tiny leak in the headers would probably go unnoticed... on our cars they become "rape whistles" as you so eloquently put it.

But hell, give it a shot. Worst case scenario is you've just got a slightly bigger hole to patch up later.

[cody]

Is this the muffler shop you went to, Scott?

http://maps.google.com/maps?hl=en&ie...A&iwd=1&dtab=2

[cody]

Rusty didn't say nobody in Reno could do it, just that he didn't know of anyone who could. But I really want to call the shop that you had your headers welded at.

[sperry]

Originally Posted by cody

Is this the muffler shop you went to, Scott?

http://maps.google.com/maps?hl=en&ie...A&iwd=1&dtab=2

Yep.

But who are you gonna believe, me, or some SRT-4 owner w/ a blown up car posting on google maps? WTF is a "blown respirator" anyway? Is that grandma's oxygen tank?

Anyway, I got my headers welded there back in 2002 or so. In fact, I believe Dean still has those headers on his car, unless he didn't swap the headers over to his STi when he sold his WRX.

[cody]

Ha! I didn't know the link was going to pull up the review. I'll give 'em a call.

[cody]

Spoke to a real nice guy at McVay's and he actually suggested that what I plan to do is the best solution. I said wow, thanks, but if it does back out or leak or whatever, can you guys weld cast iron and he said they might be able to wire weld it on the vehicle, but he said, "after a couple heat cycles, that grade 8 bolt is going to practically weld into the hole with the swelling and contraction of the metal."



So now I have Rusty, Ansel, and some nice muffler shop guy telling me I'm doing the right thing. Guess it's worth a try.

Oh, Dean and Kevin too.

[sperry]

Originally Posted by cody

Spoke to a real nice guy at McVay's and he actually suggested that what I plan to do is the best solution. I said wow, thanks, but if it does back out or leak or whatever, can you guys weld cast iron and he said they might be able to wire weld it on the vehicle, but he said, "after a couple heat cycles, that grade 8 bolt is going to practically weld into the hole with the swelling and contraction of the metal."



So now I have Rusty, Ansel, and some nice muffler shop guy telling me I'm doing the right thing. Guess it's worth a try.

Oh, Dean and Kevin too.

Originally Posted by sperry

But hell, give it a shot. Worst case scenario is you've just got a slightly bigger hole to patch up later.

[cody]

Oh you want on the list too? I'll see what I can do.