Hi Daniel, I use a #3 drill bit (0.2130") when I tap a hole at 1/4-28.
That's UNF at 28 threads per inch. Good Luck!!
Jack
-----Original Message-----
From: owner-spridgets@autox.team.net
[mailto:owner-spridgets@autox.team.net] On Behalf Of Daniel1312@aol.com
Sent: Tuesday, June 13, 2006 3:35 PM
To: spridgets@autox.team.net
Subject: Drills, taps and hardware
Hi List,
Collected my hybrid bellhousing today. This is to fit a Ford type Nine
5 speed gearbox onto the back of an A-series engine. The bellhousing in
the car is an earlier fabricated bellhousing that the casting will
replace.
I've some jobs to so on the casting including drilling and tapping 3
quarter UNF holes for the starter motor cover (will be blanked off since
the car uses a pre-engaged.
SO, what size drill do I need if I'm going to tap a quarter UNF?
Secondly, the bellhousing has a steel bracket that takes the clutch fork
and this screws into the bellhousing with a pair of metric M6 Allen
caps. I'd like to not only Loctite these 2 bolts into the casting but
I'd like to lockwire them to the pivot bolt for the clutch fork (I
realise this is overkill). I can't drill the bolt heads without a
drilling jig (my jig is imperial not
metric) and Allen caps are a sod to drill anyway.
SO, I don't suppose I can just run my quarter UNF tap down the metric
M6 thread and get away with it can I (I know it's shameful even to ask)?
OR anyone have a source for drilled head metric hardware - Aircraft
spruce only does imperial stuff?
Thanks
Daniel
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