Drilling Cast Iron......

oldsmobile joe

Royal Smart Person
Nov 12, 2015
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mpls
:popcorn:
 

Bonnewagon

Rocket Powered Basset Hound
Supporting Member
Sep 18, 2009
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Queens, NY
Cobalt bits, cutting oil, beer.
 

79 GP 4 speed

Master Mechanic
Nov 12, 2017
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Start with a small drill bit and work your way up in size. Go slow and use some kind of lubricant, when I drilled the exhaust manifold on my truck I used grease to stop a lot of the shavings from falling in.
 

gnvair

Royal Smart Person
Sep 1, 2018
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Southern New Jersey near Philly
A machinist friend of mine said cast iron is best tapped slowly and without lubricant. I have used his advice on many iron items including tapping a Vortec 350 block that was missing bolt holes for installing a metal timing cover AND tapping a missing accessory hole on the right side cylinder head of the original 305 in my Malibu when installing the serpentine brackets. Again, this is just my $.02
 

Wageslave

Royal Smart Person
Jan 25, 2017
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Maybe I just have better luck than most, but I just grab a uni-bit and a cordless drill and try to keep the bit straight. Haven't shattered one yet.
 

fleming442

Captain Tenneal
Dec 26, 2013
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The 2 things I got from the thread were: iron has a lot of graphite- that's your lube, so go dry and cool with compressed air. I tried it, and it works.

That, and oil makes lapping compound out of the chips.
 
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