the hole is 13/16" in diameter

the hole is 13/16" in diameter

 

 

Looks like 3/4 NPT is your animal. The tap drill size for that is 59/64

 

Again, a good hardware store should have both the taps and the drill, but you may be stuck buying a set. MSC carries the tap and the drill individually for not too much. They carry both import stuff and USA made, so it's up to you how much you want to spend on the stuff,

 

their website - http://www.mscdirect.com

 

Tap - $16.29

http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=04350070

 

Drill - $19.91

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1682675&PMT4NO=37018041

 

 

Grizzly Tool is another discount tool dealer like harbor freight. they've got an NPT set for about twice the price as the single tap from MSC. It's total junk I'm sure, but if you only need to do the occasional NPT tapping...

 

http://www.grizzly.com/products/6-pc-NPT-Tap-Set/H0465

 

The 59/64 is not a commonly used size so most places may not carry it as an individual bit, so you may be stuck buying it singly on line.

 

When you do the tapping, most taps have a center drilled hole in the back of them. Since this is a pretty big tap and it's gonna take some meat to move it, you might have a buddy help hold things straight. If you have a center punch and hand drill, put the center drill in the chuck of the drill and have your buddy hold it against the back of the tap. That way he/she can hold the tap straight while you crank that bad boy around with a wrench. Also, use some sort of cutting oil. The hardware store should have something available with their taps. Also, don't drive the tap too far in, like only about 1/2 way up or else the threads will get too big and the plug won't seal.

 

anyway, ramble ramble... My comments aren't meant to demean your tapping abilities, you could very well be a tapping ninja. But in case you aren't...

 

Good Luck!

 

Will-

my trick ith thee holes is to cut off the pipe and weld a cv ball into the hole, i have done that on old ea motors and 1 ej, works and is quick, and uses what laying around

i have the plug ready to go in. seems to be a regular plug, doesn't say "tapered" or anything like that on it, they didn't have any like that.

 

coat the threads with exhaust sealant and call it a day?

Gary, the plug is no doubt tapered.

 

To assist in this endevoure I suggest you

take a small triangular file

and file notches in the thread to simulate

a tap.

 

Only a few threads from the bottom of the tap.

 

Thes notches are places for the chips to reside.

Here is what it looks like

(crude drawing but effective?)

 

 

Run it in a few turns take it out clean the chips

then coat with the ju ju and run it home

past the filed notches.

i have the plug ready to go in. seems to be a regular plug, doesn't say "tapered" or anything like that on it, they didn't have any like that.

 

coat the threads with exhaust sealant and call it a day?

 

 

Skip's got the ticket with the file trick. Though, it is possible you picked up a straight plug. Easy to find out after you've filed the notches in and you're running it in and out to clean the threds. If you're able to run it all the way in, then either your threads were cut too deep or your plug is a straight plug.

 

Or if you have a caliper, measure the top and bottom of the threads and look for a difference... tho if you have a caliper you've prolly already done that:)

 

Will-

wowsers, nice hit on that drawing skip. you're the man.