Best drill bit to drill my exhaust manifolds

[samson_420]

Well, I decided to keep my stock exhaust manifolds and get a off road Y. I still don't know which one, MAC or DynoMax. Either way, I broke every stud on the driver's side manifold, the other one came out real well.

So, I ground down the studs with a cut off wheel and made some nice pilot holes. But, I still need a good quality drill bit to drill through the studs so I can use bolts.


I need a real sharp bit, this is in a real tough place to drill.

[MUSTANGBRKR02]

use a bit made for steel use a slower drill speed(speed creates heat dulls bit) and use a little bit of oil on it.

[bowtieboy10]

if you have a torch or anything heat it up and use a hamer and punch and you should be able to drive them out. it might be easier than drilling. cause like mustangbrkr02 said you need to run the drill slow to let it cut and not dull the bit so fast. either way good luck

[99345hp]

If you are really good with a torch you can burn them out without messing up the hole or threads.

[samson_420]

^ Ha, yeah. . . It's a bit passed that.

Now I just need a good qiality bit.

I am thinking cobalt, maybe? It ate my carbine masenry bit up with the quickness.

[99345hp]

No its not past that at all. Put the tip of the torch right in the center of the bolt. Heat it up till the bolt is cherry red. Pull the trigger and if should blow most of it out. Then it will be much much easier to drill the bolt out.

[samson_420]

Uh, no. . .

I have no torch, no welder. . . But a few quality high speed drills.

[87gnx]

Use a Cobalt bit,some light cutting oil, slow speed on the drill not pushing too hard.Take your time. Never a masonry bit on anything but concrete. $.02

[jsteele90]

cobalt bit+1

[MUSTANGBRKR02]

torch would be a bad idea used that way if you get drip on the tip and send that flame the other way you won't need to worry about a broken stud. A cobalt bit would do good but like i said slow speed and some oil and it should cut fine.

[blk/slvr02ss]

Take them to a Machine shop so they get done properly and less of a problem for you.If not i would use a titanium bit.I would go w/ the mac off-road y-pipe it knocked 3tenth off the 1/4 in a 98 Z-28 i had.

[SoxXpupPeT]

carbide

[jimmyblue]

Cobalt bits will chew through the stud just fine,
you have to watch the quality on carbide and
"titanium" (nitride) bits as these often are a
"dumb homeowner hoax" (soft steel except for
the coating or tip, but it says titanium so you'll
buy it). But cobalt bits are hard all the way
through. Which means you can sharpen them
again, too.

I'd pick up a 1/8" for pilot as well as the root
diameter (if replacing studs or reusing the tapped
hole) or outer diameter (nut & bolt plan).

I've never had problems with cobalt bits other
than occasionally snapping one in deep holes
(just make sure you pull out occasionally & keep
the swarf from loading the flutes entirely).

[samson_420]

Thank you all for the advise, minus the torch idea.

I used a cobalt bit for the main holes, and just hardned jobber bits for the pilot holes. I kind of did it in a stepped process. I did a small pilot hole, then a larger one and so on.


It was tough, relly due to the fact I was laying on my back trying to apply pressure to the drill.


Mac pipe it is. . . . . .

[zdawg28]

Craftsmans Professional Cobalt.