Little help here

[Squirtcha?]

Swapping out the intake. Everything came apart real nice. Gaskets looked so good, I was tempted to use em again (kidding).
http://www.jetheaven.us/photopost/da...th_the_old.jpg
Here's the first problem I ran into. I was plumbing up the TR and noticed that the hole had never been drilled and tapped for my Bassett T valve fitting/adapter.
I have a 3/8" NPT tap however I know I don't have a drill bit big enough to drill it out first. Does anybody know what size hole you have to drill to tap it out to 3/8" NPT? This means a road trip right in the middle of the job. Thought I had my stuff together, but apparently not.
http://www.jetheaven.us/photopost/da...st_problem.jpg
Tub o' used parts.
http://www.jetheaven.us/photopost/da...used_parts.jpg
Thanks in advance for any assistance you can give
Dan aka Squirtcha?
P.S. It pains me to take apart a boat that starts with the bump of a key, runs all day long. Runs as hard as you want it to and does it every weekend. AAAAAhhhhh crap. What the hell.

[GlastronGuy]

On second thought, that site doesn't look right. Better double check

[Squirtcha?]

Beautiful. Thanks a bunch Chris. Now to find 37/64 that will chuck up in my little 3/8 Ryobi. I got my doubts on that one. Home Depot Tool Rental Center here I come.

[GlastronGuy]

Double check the drill size with another site. It looks wrong.

[Squirtcha?]

I'd have a hard time finding it. My search is down right now. Daughter messing around and got me good.

[GlastronGuy]

here (http://www.newmantools.com/tapdrill.htm)
and here (http://www.engineersedge.com/tap_drill_chart.htm)
I think it is OK. It just seemed wrong at first glance.

[Jake W]

When you buy a TAP it tells you what size drill bit to use for it so if yours doesn't go to the local hardware store and look on a tap package for the info.
Jake

[Squirtcha?]

Yeah, I used yahoo. Found three sites in addition to the first one you gave me. 37/64 it is. They all said the same thing. Thanks again buddy I appreciate the assist.

[Old Guy]

You're gonna need a large drill to handle a bit that size. It's important to get one that has a 2 hand grip. That drill is .5781". That's a little more than 1/16th" bigger than 1/2".
The tap will have a square "head". In a pinch, a 12 point socket can be used for a tap wrench. If you can't get a good fit, grind the tap square part a little smaller. Be sure to use "cutting oil" on the tap so that the threads don't tear.
Good luck
old

[HotRod Sprint]

Hey Dan, I've got a 9/16 bit and a 1/2 inch cordless drill. Need any help?
Rod