I'm just about to install my boost and pyro gauges( autometer pyro part #2654) and some people have told me 1/4 tap, the pyro probe looks a lot bigger anybody have this gauge?

 

A 1/4" pipe tap is surprising large, I did a double take when I bought mine. If in doubt, take the probe to a good hardware store and match it up.

 

my autometer was 1/8 npt and the predrill bit was just a bit smaller (sorry, dont remember the size )

 

If its an 1/8" NPT, a R drill bit is best, but I used an 11/32 (within .004"). 1/4" NPT needs a 7/16" bit.

 

Auto meter uses a 3/8" NPT tap. I believe the drill bit size is 5/16". Dont remember off the top of my head. My taps say what size bits to use on them.

 

3/8 NPT uses a 9/16 drill bit. I believe that the AutoMeter pyro probes are 1/8... Most pyro probes are 1/8 or 1/4...

 

i know it sounds confusing but 1/4 pipe thread is way diferent than 1/4 bolt thread,do you already hav the tap?it should say what size hole to drill,also be very careful when drilling,use vaseline to catch the small filings and use a vacumm with a small tube atatched to get into the manifold to suck out the filings,they will damage a turbo if they pass through,also where are you in canada?im in the okanagan in bc,if we were close i could lend you my tap and drill bit as i only used them once and may never use them again{unless i get that 03 im looking at haahaa}

 

autometers are 1/8npt and isspro's are 1/4npt. i made this mistake on my friends and drilled a 7/16 hole for it and then found out that it had a 1/8npt and not a 1/4. luckily the kit came with a bung and we were able to weld it in and use the pyro

 

Yeah I just read the so called instructions again and it says 1/8 npt but the threaded part of the probe looks huge, I guess i'll just have to pick up the tap and have a look. These gauges are really getting to me, I have every thing in the engine compartment, the pyro won't be a problem I just want to make sure ihave the right tap, but the lighting is what i'm having trouble with. I want to get power from the lighting dial on the top left of the dash but cant find the right wire, anyone know which is the right one. My boost gauge is in, I found the 3/4 plug that has to come out but I didn't get anything with the gauge except a plastic T fitting, nothing to thread into a tapped hole, anybody have these problems or am I missing somthing?

 

not sure on the lighting wire,where did u get the gauges from?i got mine from bd diesel in vancouver and i told them the year of my truck and my gauges came to me with all the adapters for the boost bolt and fuel presure adapters and came with wiring diagrams telling you which wires to splice.sounds like you need a boost bolt i think its called,or try ur local napa for a brass fitting to go from 3/8 male to 1/8 compression.ithimk its 3/8.

 

My isspro has the 1/8" probe thread.

 

I install 1/8" nptf plugs in alloy engine cases fairly often. I use the .339 drill bit, but as Tate says, the 11/32 bit is just a few thou larger, and I would probably grab it first for cast iron.

 

Weel I got everything in and it all works well, used the light brown wire and the gauges dim with the lights. I went to a local diesel shop and got the brass fitting and tapped into the intake horn, I looked at the instructions at the diesel shop and they say to use a 1/8 npt tap and a 5/16 bit for both the boost and the pyro the boost went in fine but the pyro probe went in about half way( the nut is not tight with manifold) I went to tighten it more but didn't want to strip it, does this sound right?

 

Sounds right.

 

NPT, as stated above, is not the same as bolt thread. It has a smaller diameter at the tip tapering to a larger diameter. This acts like a wedge when it is screwed together.

Jim