11/16" drill bits

Just about any hss twist drill will drill cast iron with no problem, run it dry and you should be able to drill dozens of those holes before it needs sharpening.

whichever bit you use, drill a pilot hole, with a 1/4 inch bit, then enlarge it with several other sizes, before tackling it with the 11/16 bit.  If it is very hard, the other bits will tell you...

yup start small, go up in steps.
my luck is I'd need 4 drill bits as the quality of bits these days is well, krappy.
I find I need oil to keep them sharp for any length of time
Got 4 coffee cans FULL of bits, dull bits, from 1/4 to 1 inch.Never learned how to sharpen them,sigh

BTW I'm sure my 8N had a temp gauge..so curious your don't ?!
Jay

If you want to sharpen a bit don't use a real fine grit stone. They put to much heat into the bit without removing much material. Make sure the stone is sharp and square across the face. Take a sharpie and mark the bit where you want to grind to. Take your time and practice, practice, practice. You can do it.  Leon  CMo

No oil on cast iron. Steel, use cutting oil, not motor oil.
Last pilot hole should not be larger than 1/2 the size of final hole.   MACK

kinda big hole, I would NOT want to be using a hand drill in case it grabs, as it'll toss  you across the shop or bust a wrist.
be real careful, maybe secure drill with chain to prevent an accident.

Edited by desertjoe - 05 Jan 2018 at 9:12am

no oil is needed to drill, but use lard to thread. Works like a charm...

If you want to stay on an exact center only use one pilot drill and no larger than a 1/4" drill for a 11/16". The smaller hole will hold the 11/16" bit on center.
Every time you drill a larger size you increase the chance of the center of the drill leading to one side. If and when one bit leads off the hole is on a slight angle with the top of the hole staying on center. Each jump up in size when step drilling the angle will be greater once it starts to wonder. If one of the step drills had one side slightly duller than the other it will be more likely it will wonder.

I understand step drilling larger holes when your drill does not have the power to turn a larger bit where your not trying line two holes thru thicker metal.

When I am drilling larger holes in the 2" range thru two plates I do it on a mill and then bore the final size. You would be surprised how far off you can be with a drill bit.

If I was doing your job I would use the head as a drill guide for the hole in the block.      

   

My experience with drilling cast iron, is that there's really good iron in really good, clean castings, and then there's everything else.

Let's say you're drilling holes and tapping them 1/4-20 or 3/8-16 into the column of a Bridgeport J-mill, or the back of a Monarch 10EE... to mount a control cabinet for variable frequency drive.... the iron is excellent, and the casting is clean.  Drilling is easy... even with a cordless drill, I'll do 'em in one shot, with ordinary jobber-length drill bits, and I even tap them dry... I'll use an air  hose to blow the spoils clear, other'n that, no worries.

But... I've found some castings where the iron is substantially less than good... and I've found some that there was casting sand caught up inside the iron... got in there, hit a piece of sand, snagged the bit, and bam... broke it right off...

I have never done it, but my gut feeling is that the Ford N cylinder head is probably not in the category of a Bridgeport J-mill or a Monarch 10EE lathe...  Henry didn't strike me as the kind of guy who concerned himself with the quality of a casting... Seems to me that their program was that if it fit, and didn't leak much, it went out the door... 

That being said, I DID do a cooling system modification to the Ford 192 in my Hyster H50H forklift, and it included drilling, then counterboring and tapping the head for a coolant bypass between #2 and #3 cylinder... and the head drilled okay.  That was, however, an 'industrial' engine... so it may be a different story... I dunno.  I know that the 192 is the weakest four-cylinder engine I've ever owned, but that means absolutely nothing in terms of the casting quality and workmanship...