kraaazymike

iTrader: (2)

I'm new to tap and die sets and I'm trying to install an autometer sender for my oil temp gauges. The sender itself is 3/8" but I don't know how many threads per inch it has. Anyone know if I can use a 3/8" tap with 24tpi or do I have to use the 1/8" tap like it says on http://www.xse.com/leres/ss/gaugepod.html.

Or should I just pick up a 1/8" NPT pipe tap?

Thanks for any help!

theblur98ss

iTrader: (71)

I'm thinking it's 1/8" npt but I could be wrong. Your best bet to be sure may be to take the sender to the hardware store and have them match the threads to the tap size you need.

Weezzer

Its 1/8" - 27 NPT, this is a tapered thread that helps seal itself from leaks.

The tap you can find pretty much anywhere, but you will also need the tap drill - this will be harder to locate than the tap. Its drill letter "R" - 0.339" diameter. You will need this to finish drilling thru the fitting (there is a partial hole already there).

When you tap it, be sure to stop tapping when the tap reaches a depth that leaves 6 to 7 "full" threads before/from the top of the tap. If you go too deep you may not be able to get it to seal. Like I said, this is a tapered tap - so the deeper you go the wider the hole!

kraaazymike

iTrader: (2)

Great advice guys, you've been very helpful! I'm gonna head out to find the right sizes.

kraaazymike

iTrader: (2)

Alright, I cant find this thing anywhere but I did find the 1/8npt. Would it be possible to install the sender without the "R" drill and just use only the 1/8npt? I'm not really visualizing what you meant by "finish drilling thru the fitting". Just asking because the author didn't mention using a "R" drill in his write up at http://www.xse.com/leres/ss/gaugepod.html

Weezzer

http://www.xse.com/leres/ss/images/cover-sm.html

This piece isn't drilled thru on the F body, its just mounted there right above the oil filter. This picture shows the finished item after drilling/tapping and fitting of the temperature sender.
On the Vette this piece has already been drilled and is fitted with the temp sender. It is a functional piece on the Vette. The F body has a semi-finished hole, you must drill thru it and tap it for the probe to reach into the oil stream. If the hole was already there now you'd have a hell of an oil leak since nothing is plugging the hole.

On his site he says use the 21/64 drill, this is .328" diameter - if you have experience in using taps it can work but its 0.011 too small. If your not carefull the tap can bind and break as the aluminum this fitting is made out of is really gummy and will want to stick/load up the tap. Be sure to use some kerosene or WD-40, anything to lube the tap somewhat.

Quote from his site:
"However, the F-Body version of the cover (GM 12551595) is not machined and it's easy to drill it 21/64" and tap it 1/8" pipe. "

He is incorrect on the drill size as I pointed out, the correct drill for a 1/8-27 pipe tap is 0.339" (R size).
Your gonna have to find a "real" hardware store to get the correct drill, shouldn't be more than $3.50 but your not gonna find it at any Home Depot or Lowes.
Your going to have to find an industrial supply hardware store.

slt200mph

iTrader: (42)

You could use that same place to put a fitting for a mechanical oil pressure guage too ..right??

kraaazymike

iTrader: (2)

Oh ok I get it now. I went ahead and unbolted that sender base and tapped it with the 1/8-27 after drilling through the hole and mounted the sender. Seems to be working fine thus far without and leaks! Thanks for all your help!

210 seems to be the average operating temp on this oil temp gauge of mine. That seem about right?

forecastvideo

that is the same spot i put my oil temp sender. it works great! i have prosport gauges though so my install was a lot easier =D