Engine/Transmission (1994 - 1998) Help !!!!

[TravisG]

O-kay, I am trying to do the gauges on my truck. I have an Auto-meter Ultra Lite EGT gauge. What size drill bit do I use to drill through the manifold, and what size tap, and thread count do I use to tap it. I have looked at several directions on the web, and can not find the right size, the directions auto-meter sent said to weld the port into place, and I can not do that. The directions from tst say to drill a 5/16 hole and use a 1/8 tap, forgive me if I am wrong or just confused but isn't 5/16 bigger than 1/8, maybe I read it wrong, or I am just plain stupid. I would appreciate the help from you guyz with these gauges. Thanks a lot.

 

[Joe G.]

The tap is 1/8" NPT. A pipe thread not a machine screw thread.

 

[TravisG]

o-kay I get it now

O-kay Joe, I get it . So the 1/8-27 tap I got will work, and a 5/16 drill bit.

 

[Joe G.]

I don't think so if your tap is a straight machine thread for a 1/8" hole. You need to buy the NPT (National Pipe Thread) tap instead. The 1/8" NPT thread is a tapered thread. The 1/8" refers to the ID of the iron pipe that uses this size thread so it is just a little smaller than the OD of 1/8" ID iron pipe. The tap will have NPT on it and have an obvious taper for the whole tap, not just a taper in the first part of the tap that is used to start the tap for a straight machine thread. An NPT tap is kind of short and squatty looking.

 

[TravisG]

The tap that I have says: "1/8 - 27 pipe" on it. The package that it came in says: "1/8- 27 pipe tap N. C. Thread" and then "Standard". It is about two inches long. The actual part of the tap that cuts the threads is about 1 inch long. I think that this is the right one, but am not sure. I am about to just give up on the whole thing and pay somebody to do it. I can't afford to screw this up, and not be able to go to work on Monday. And to top it all off the box has no directions in it saying where to mount the other two black and red wires coming out of the bottom. I know that the black one is obviously a ground, but exactly where do you mount the red one to (+) a constant 12v source or what. I hate to sound like a real idiot on here but I am just starting to learn a little about these. I really appreciate all your time Joe, and any one else that responds to this.

 

[illflem]

Don't think there is a 1/8'' bolt size, under 1/4'' the sizes are usually expressed as numbers rather than fractions. You've got the right one.

Connect the red wire to a switched 12v + source

 

[Dennis Garrett]

When you drill the manifold, make sure you don't drill dead center. There is a rib cast in the inside, & you can't put the probe there. Locate the center, then put it left or right of the center to avoid the rib. Drill a pilot hole first.

 

[dlange]

travis,



Did you get them installed? If you need some help I'll be glad to meet you some night and give you some help. Till then, BOBM ON.