Lunar240z Posted August 5, 2006 Share Posted August 5, 2006 what size should i drill a hole when tapping it for 1/4 npt? is there maybe a chart somewhere that has a bunch of this info? Quote Link to comment Share on other sites More sharing options...
Dave Posted August 5, 2006 Share Posted August 5, 2006 what size should i drill a hole when tapping it for 1/4 npt? is there maybe a chart somewhere that has a bunch of this info? There are some nice charts here. Looks like 1/4 npt is 7/16" http://www.engineersedge.com/tap_drill_chart.htm Quote Link to comment Share on other sites More sharing options...
slownrusty Posted August 5, 2006 Share Posted August 5, 2006 Handy chart..I need to reference that today ironically. Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted August 5, 2006 Author Share Posted August 5, 2006 thanks ! Quote Link to comment Share on other sites More sharing options...
award280 Posted August 5, 2006 Share Posted August 5, 2006 I was just looking for that as well. Thanks. Quote Link to comment Share on other sites More sharing options...
Mike C Posted August 6, 2006 Share Posted August 6, 2006 Your tap should be marked with the drill size you need. Quote Link to comment Share on other sites More sharing options...
Some-Guy Posted August 11, 2006 Share Posted August 11, 2006 go into any machine tool store anywhere and get a pocket size one! There handy as hell drill size, tap size, and decimal equiv... and there free... Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted November 13, 2006 Author Share Posted November 13, 2006 Another question. About AN taps... I couldn't seem to find any searching online, so are they just the same as their standard equivalent? e.g. a -8AN tap, the same as a 1/2 tap? [because we all know that that -8AN = 8/16"] Quote Link to comment Share on other sites More sharing options...
johnc Posted November 13, 2006 Share Posted November 13, 2006 [because we all know that that -8AN = 8/16"] Nope. The dash number refers to flow rate of the hose compared to a metal hard line OD measured in 1/16" of an inch. So, a -8 hose flows the same as a 1/2" OD metal hard line. A -8 hose ID is less then 1/2" and the OD is greater then 1/2". Generally you don't thread a AN threaded fitting into a hole unless the hole has the 37 degree taper at the bottom that the fitting can tighten up against. You can put a AN fitting into a hole if you use copper or o-ringed washers get a good seal. I would only do this in a low pressure (under 50psi) application. Measure the thread diameter and pitch of the AN fitting to determine the proper tap. Quote Link to comment Share on other sites More sharing options...
mason4300 Posted November 13, 2006 Share Posted November 13, 2006 ah, good. I'll use this as well. Gotta tap one of the holes in the engine block where the water pump bolts in... Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted November 13, 2006 Author Share Posted November 13, 2006 ok. thanks for that. thats what i always was told. i'm using the fitting for a custom sr20ve [not a typo. ve] fuel rail. its a -8 oring fitting. i guess i'll take it to the hardware store and find out there. do you measure from the outside edge of the threads? Quote Link to comment Share on other sites More sharing options...
mason4300 Posted November 15, 2006 Share Posted November 15, 2006 (ignore this post. I accidentally unsubscribed from it in my usercp, so I'm posting to make it stay there.) Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted November 17, 2006 Author Share Posted November 17, 2006 just passing this along, -8 was for sure 3/4" 16 threads and -6 was 7/16" 18 verified correct Quote Link to comment Share on other sites More sharing options...
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