gtaylor
Forum Newbie
Posts: 20
Reg: 11-28-10
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05-07-12 06:01 PM - Post#2223564
I've got a 1963 Belair with the 8-cylinder 283. While trying to loosen one of my two thermostat housing bolts, I had a break, with about 1/8th of an inch loose. I tried tapping and vice grips, and even an ez-out, but nothing would budge it. I resigned myself to drilling it out, but it appears that none of my bits can even get biting into the metal.
I used a punch to get started, then used my smallest cobalt bit, but I got nowhere. I tried going bigger, with no luck. A carbide bur + a dremel seemed to at least get it started, but even that was really slow.
What on earth are these bolts made out of, and what kind of bit do I need to cut into them? The drill was definitely going in the right direction, and I had used these bits to drill out the carb to manifold bolts, so I'm at a loss as to why I'm having no luck getting these bigger ones out.
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 dcairns
"4th Year" Silver Supporting Member
Posts: 1539
Loc: Orange CA
Reg: 11-07-03
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05-07-12 06:24 PM - Post#2223579
In response to gtaylor
Tungsten carbide bit in a Drexel will let you carve it out.
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YOUNG57
Contributor
Posts: 466
Loc: Franklin TN
Reg: 12-06-10
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05-07-12 07:27 PM - Post#2223600
In response to dcairns
Bolt steel is very tough; even grade 5 which is very common for these applications. Drilling out bolts requires good quality sharp drills. Drill bits that have been used before to drill out bolts will have been hot (softened) and dulled (lost its cutting edge) and no longer capable of cutting into tough steel.
A new and still sharp high quality bit should get a small pilot hole (1/8”) into the bolt you can enlarge to get a big enough ez-out into the bolt to remove it.
Soak the threads with some penetrating oil and even a little heat around the area to loosen the bond to the intake. Hopefully you can save the threads in the intake so you won’t have to repair it.
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1965C-10
Very Senior Member
Posts: 6729
Age: 35
Loc: San Tan Valley AZ "Phoeni...
Reg: 11-18-01
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05-07-12 08:27 PM - Post#2223617
In response to gtaylor
I was putting a Carter AFB 600 carb on a 350 once, and one of the bolt holes for the carb mounting broke in half, it was a 1970's era manifold.
After getting mad, and thinking "why did I have to change carbs?" I decided it was a perfect excuse to put on a new Edelbrock aluminum intake, went with the Performer for small block Chevy.
I would understand though, you may want to keep the car with original parts, just a option if those bolts give you a lot more trouble! 
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 62chevy427
"7th Year" Silver Supporting Member
Posts: 1499
Loc: laurens sc
Reg: 04-13-06
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05-07-12 08:28 PM - Post#2223618
In response to YOUNG57
it helps to use a varable speed drill and turn the drill bit slow and use some cutting oil.. the stee will work harden when the drill turns too fast.
56 bel air ((since 2002)
62 impala ss (since 1965)
65 el camino (since 1969)
66 nova (since 1987)
67 malibu convertible (since 1981)
72 el camino ss454 (since 1985)
83 gmc 4wd (since 1991)
95 impala (new)
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junky
Contributor
Posts: 888
Reg: 06-27-10
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05-08-12 05:44 AM - Post#2223700
In response to gtaylor
My experience has taught me that it is faster, and less expensive to take it to a machine shop that has experience removing broken bolts. If you mess it up, you will be buying a intake manifold. If you want to keep the car "original as built", give it to a machine shop to remove the broken bolt. It will be less expensive in the end. We all have different levels of expertise, and if you haven't removed broken bolts before, this isn't the time to start learning. You learn on parts that you don't care about to get experience.
Never argue with an idiot. He'll drag you down to his level, then beat you with experience.
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gtaylor
Forum Newbie
Posts: 20
Reg: 11-28-10
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05-08-12 08:02 AM - Post#2223742
In response to junky
My experience has taught me that it is faster, and less expensive to take it to a machine shop that has experience removing broken bolts. If you mess it up, you will be buying a intake manifold. If you want to keep the car "original as built", give it to a machine shop to remove the broken bolt. It will be less expensive in the end. We all have different levels of expertise, and if you haven't removed broken bolts before, this isn't the time to start learning. You learn on parts that you don't care about to get experience.
Yeah, you're right. I think I'm going to do this.
I've got this thread bookmarked the next time I break a bolt off somewhere more forgiving, thanks to everyone for all of the advice!
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