Got almost all my parts together for my new gauges except for the pyro lead wire,, Of course the gauge dosent come with one. What Do Ya'll use? I have several kinds of wire what should i use?

 

I'm new to this forum, so don't write this in stone. But in aviation, where there is a thermocouple (pyro sensor on PSD's) they usually use inconel and monel welded together in the sensor and inconel and monel OR kapton wiring is used. Think there should be wire in your gauge set up to match components...What kind of gauge did you get & from where??? I would like to know cause I'm planning my gauges.

 

Got my pyro from here at Motorhaven,, had to get the thermocouple directly from isspro,didnt come with that either, Never thought to ask if it came with a lead wire. Just has two terminals for the wires to connect too but thats it.
I think most of the pyros i have looked at didnt include the thermo or the lead wire,, I guess cause of different mounting locations and etc. i got the clamp on thermocouple, now i just need the wires to it. I didnt know if it took a special kind of wire or what, theres a lot of heat in that area thats for sure.....

 

the wire should have came with the thermal couple.

 

Yea, like Wlihnter said - your actual thermo-couple should have a short (2-3 feet) lead on it - then there should be a seperate pair of wires that go between the thermo-couple and your gauge. You can't just use any wire like you can from an electric sender and gauge (like a trans temp gauge) - you gotta get a hold of the right matched stuff to have the gauge reading right. My Autometer gauge came with a warning that you can't lengthen OR shorten the wire between pyro and thermo-couple....

 

The way that a thermocouple works demands that the correct wire be used. There are several types of wire made of different metals.
The basic way it works is that it is a junction of two types of wire. For example one common type uses chromel in one wire and alumel in the other. when the two wires touch together they generate a voltage (millivolts). The amount of voltage that they generate is in response to the temperature of the junction. That's basically how it can sense temperature. It is a wire junction with a tubing sheath over it to give it some durability.
If you were to connect the chromel wire to a copper wire, you would have another junction of two metals. This new junction will also create a millivolt signal that will introduce error to the original millivolt signal.
The wire color will tell you what type of metal it is, and thus what type of thermocouple you have. Certain metal combinations read more accurately than others in different temperature ranges. The most common types you will see are type "J" (red and white wires) and type "K" (red and yellow wires).


Cat-MAn-
You can lengthen or shorten the wires on a thermocouple. The trick is that it must be the same type of wire as the one being lengthened or you will get the dissimilar metal junction that causes error. I have seen thermocouple leads over 10 feet long, and under 6" long. Both worked fine.

 

I appreciate the help for sure.. i did think it was funny that the thermo didnt come with a wire, but what do i know..!! It does have about 6" of wire with 2 screw on terminals at the ends. I'll call Isspro tomorrow and get the right stuff. Will 6ft be enough or do i need 10ft to go to the dash from the up pipe? The last gauges i had (the borrowed ones) had probably a 10ft lead wire,, cause i had lots left over. Was Planning on the install this weekend, but it may have to wait another week,, Till then i'll be running around NAKED without gauges . Its a real drag not to have gauges after you've already had them, let me tell ya..!!

 

You have a type K thermocouple which uses chromel (+) and alumel (-) leads in an inconel housing. You will be looking for leads of the same materials. Like bodabdan said, it will have a red and a yellow lead in a yellow jacket.

 

Sorry - NOT true. You can get different lengths - but you are NOT to change what came with your gauge. I dug up my Autometer directions again - and that's what it says. It says to coil up any extra wire - DO NOT shorten the thermo lead, or the gauge will not be accurate!!!