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View Full Version : Any Tips for Drilling & Tapping an Exhaust Manifold stud?


gr8fulabe
04-07-2012, 10:07 AM
Hi All,

One of the three threaded studs that mounts the upper exhaust tube to the exhaust manifold on my 84ish 2F, had to but cut off. Is it possible to just drill a new hole, tap it & put in a new stud, or does that not work on cast iron? Any tips here?

Any idea what size the studs are?
Thanks,
Abe

gr8fulabe
04-07-2012, 02:51 PM
No need for advice! New stud is in place!

Thanks
Abe

MDH33
04-07-2012, 03:05 PM
You're fast. :D

So for the sake of making the thread useful in case someone else has this problem, what did you do to fix?

baja1d
04-07-2012, 10:37 PM
Abe-

It appears that you and I are performing very similar swaps/mods. Let me know if you need any help or run into a snag... I'm in Littleton BTW.

Here's my plans: The 2F is going in this week along with the H55, split case w/ parking brake drum attachment, and tilt column/power steering. In addition I'll be installing a 4" alcan lift and wheel spacers.

Rzeppa
04-10-2012, 12:27 PM
The best way to remove old, stuck, broken rusted out broken bits of bolts or stud is to start out drilling a smallish hole as close to the center as possible. Gradually increase the diameter of the drill in steps, typically at least 3. As you start to graze the inside edge of the female threads, now it is time to run a tap through there. Often as not the tap will catch what remains of the bolt or stud and thread it right out. If not, you are still basically just chasing the threads and doing minimal damage.

Whatever you do, avoid using extractors (EZ-Outs). When they break off, now you have bits stuck in there that are as hard as or harder than drill bits themselves.

gr8fulabe
04-10-2012, 10:24 PM
27955

27956

27957Hey Jeff,
That is basically exactly what we did, but we tried the Ez-outs before going to the tap.

1. used a grinder, super briefly, to flatten the broken stud.
2. We used a nail as a center punch, to put a little point on the old broken stud.
3. Drilled a small hole & tried to use ez-out. Repeated with several slightly larger ones to no avail. We used WD-40 while drilling as a lube, which seemed fine, but I have no idea if that is a good option.
4. Got to the point where we could start to see the threads, and tried the last ez-out for that size hole. didn't work.
5. Found one of the bolts that fit, and took it to Napa to get a new stud. They have a rack that has this sort of stuff on it, and had a pack of two, for $5.14. I lost the package, so i don't recall the size now. Hopefullly someone else can fill in that detail (something like m1.5x18 or so-ish).
6. Took the new stud (a tiny bit long, but otherwise a perfect match) to my friend's neighbors garage (he's building a plane in there, so he has it all). He pulled out a tiny guage that looked a lot like a feeler guage, but every piece had grooves on it. He fit the guage to the grooves on our post & told us the size, then loaned us the right tap for it.
7. While at Napa we also bought a can of actual cutting oil, but no clue if that is any different than WD-40.
8. one squirt of cutting oil & the tap chased the crap out of the treated pretty easily. pulled it out, shot a blast of air in to clean it out.
9. Threaded new post in without any trouble.
10. Pics of the new post attached up above.

Hope maybe this helps someone in the future. Sorry I lost the package of the correct studs...

Best,
Abe

gr8fulabe
04-10-2012, 10:31 PM
The pics make the new post look smaller, but I swear it is the same size.

also, Travis, we got the engine/tranny/transfer mounted up this last weekend. I'll post up some updates in that other thread. Maybe it will help you, and if not, at the very least maybe we can be an asset to each other as we work out the details...
best,
abe

SteveH
04-11-2012, 10:11 AM
Cutting oil is radically different from WD-40. It should be high in sulfur (hence it may stink) and offers high load protection for the drill bit. Tap Magic (sold at Grainger, among other places) used to be a chlorinated solvent, but is now an oil, too. I have used anti-sieze compound on taps, too, for better or worse. There was nothing wrong with shooting WD-40 into the hole initially, but it's not a suitable lube for drilling and tapping.

Rzeppa
04-11-2012, 11:25 AM
X2 on the WD-40, it is pretty worthless for the 2 things most people (attempt) to use it for, lubricating and penetrating. For cutting oil I use marvel mystery oil, although as Steve points out, the ones that contain sulfur are best. I have also seen cutting waxes, and even water soluble cutting lubricants for use with certain types of plastics which are sensitive to aromatic hydrocarbons. For penetrating, either liquid wrench or kroil are good commercial products, or Ed's Red if you're into home brew.

Going by memory I believe that thread pitch is M10x1.5 on those (assuming 14mm hex on the nuts).

PabloCruise
04-12-2012, 05:43 PM
Or if you have access to a welder you can weld you a nut onto the broken stud and then turn it out, eh?

Rzeppa
04-13-2012, 11:36 AM
Or if you have access to a welder you can weld you a nut onto the broken stud and then turn it out, eh?

I tried that and it never worked for me. At least when the broken fastener was mostly flush with the surface it was threaded in to. The weld kept breaking off. Of course these were really, really rusted in there, which is why they broke off when I tried to back them out initially by their hex heads.

I ended up using the drill & tap method I described above, which worked well.

rover67
04-13-2012, 01:07 PM
I tried that and it never worked for me. At least when the broken fastener was mostly flush with the surface it was threaded in to. The weld kept breaking off. Of course these were really, really rusted in there, which is why they broke off when I tried to back them out initially by their hex heads.

I ended up using the drill & tap method I described above, which worked well.

the weld trick works, but you have to make sure you are getting good penetration into the broken part. that can be tough. TIG works better than MIG in this situation. The heat from the weld also helps break things loose.