Author Topic: Drilling and tapping manifold for EGT thermocouple (Read 4607 times)

GTD. · « **on:** May 08, 2008, 10:00:23 am »

I want to drill and tap my manifold for a thermocouple

whats the best way, center punch, start with a small drill bit and work up to a 1/8" then use a 1/8 NPT tap? or just 1/8 then tap using a 1/8 npt tap?

thedeezel · « **Reply #1 on:** May 08, 2008, 10:35:04 am »

The best way is to center punch where you want it, drill a small pilot hole and work your way up to the correct size hole for the tap you need to use. Use drops of cutting oil while you drill, it will help the drill bit stay cool and will help control the shavings. Same when you tap it.

saurkraut · « **Reply #2 on:** May 08, 2008, 11:30:51 am »

Get some cobalt bits.

Hot knife through butter.

jtanguay · « **Reply #3 on:** May 08, 2008, 12:12:18 pm »

also if you're going pre-turbo (which you should) then you'll need a way to control the shavings from falling inside where they might wreck stuff.

GTD. · « **Reply #4 on:** May 08, 2008, 12:26:58 pm »

forgot to say, I've removed the manifold to do this, going to drill it so the probe points into the middle of the turbo flange

Luckypabst · « **Reply #5 on:** May 08, 2008, 03:58:10 pm »

I'm a bit leery of centerpunching thin cast iron and feel safer starting slow to keep the bit centered. Uh, drill a pilot hole (1/8 - 3/16 or so), then drill to the tap size (letter "Q"), countersink and tap.

Chris

Turbinepowered · « **Reply #6 on:** May 08, 2008, 05:07:02 pm »

I put mine on a drill press to do it, but then I was also punching five holes through it. One per exhaust port and one at the common turbo inlet... the first four I tapped then plugged with steel pipe plugs, they're for future expansion.

I see a trio of dual-sweep EGT gauges in the future, mostly for reference and datalogging purposes. Cylinders 1/2, 3/4, and pre/post turbo.

Vincent Waldon · « **Reply #7 on:** May 08, 2008, 06:07:02 pm »

Quote from: "Turbinepowered"

I see a trio of dual-sweep EGT gauges in the future, mostly for reference and datalogging purposes. Cylinders 1/2, 3/4, and pre/post turbo.

Ahhh.... one of my kinda people.... a fellow gauge geek !!! If it doesn't feel like you're sitting in the cockpit of a 747 you're not done yet.

Turbinepowered · « **Reply #8 on:** May 08, 2008, 06:24:50 pm »

Quote from: "Vincent Waldon"

Quote from: "Turbinepowered"

I see a trio of dual-sweep EGT gauges in the future, mostly for reference and datalogging purposes. Cylinders 1/2, 3/4, and pre/post turbo.

Ahhh.... one of my kinda people.... a fellow gauge geek !!! If it doesn't feel like you're sitting in the cockpit of a 747 you're not done yet.

Oh yeah. Oil Temp/Pressure, Water/Fuel temp, System/Glow amps, Boost pressure/intake temp, System voltage, all three EGTs, and a clock.

Vincent Waldon · « **Reply #9 on:** May 08, 2008, 06:35:04 pm »

Hmmmm... would never thought of fuel temp. I got IP internal fuel pressure though.

Also got LEDs for glow plugs on, low fuel pressure, rad fan on, A/C clutch on.

Got switches for rad fan bypass and wastegate bypass... they have lights too... ooh so pretty at night. ;-)

Ok, we're sick. Tis true. Sorry OP... got lost there for a moment.

Turbinepowered · « **Reply #10 on:** May 08, 2008, 06:41:23 pm »

Quote from: "Vincent Waldon"

Hmmmm... would never thought of fuel temp. I got IP internal fuel pressure though.

Also got LEDs for glow plugs on, low fuel pressure, rad fan on, A/C clutch on.

Got switches for rad fan bypass and wastegate bypass... they have lights too... ooh so pretty at night. ;-)

Ok, we're sick. Tis true. Sorry OP... got lost there for a moment.

She's my test mule, I'm planning to test certain theories and methods to improve fuel economy. One of them is to use a WVO-type two-tank system to have hot and cold fuel, comparing the mileage between the hot fuel at cruising speed and the cold fuel at cruising speed.

Things like that. And yeah, I have a nice set of indicator lights mapped out too.

Sorry OP, got all gauge geeky on you!

GTD. · « **Reply #11 on:** May 08, 2008, 10:47:02 pm »

Quote from: "Turbinepowered"

Quote from: "Vincent Waldon"
Quote from: "Turbinepowered"

I see a trio of dual-sweep EGT gauges in the future, mostly for reference and datalogging purposes. Cylinders 1/2, 3/4, and pre/post turbo.

Ahhh.... one of my kinda people.... a fellow gauge geek !!! If it doesn't feel like you're sitting in the cockpit of a 747 you're not done yet.

Oh yeah. Oil Temp/Pressure, Water/Fuel temp, System/Glow amps, Boost pressure/intake temp, System voltage, all three EGTs, and a clock.

Clock? dont need a clock

Heres my little collection

just need a couple of holesaws and a few fittings and senders then just need to wire them up and fit them

Vincent Waldon · « **Reply #12 on:** May 08, 2008, 10:59:26 pm »

Dude... you're killing me... I've been looking for a VDO ambient temp gauge for decades. :wink: And it's even in Celsius...

Sigh.

saurkraut · « **Reply #13 on:** May 09, 2008, 06:57:40 am »

Quote from: "GTD."

I want to drill and tap my manifold for a thermocouple

whats the best way, center punch, start with a small drill bit and work up to a 1/8" then use a 1/8 NPT tap? or just 1/8 then tap using a 1/8 npt tap?

Drilling these maniflods is easy. I've drilled two so far with a hand held electric drill and fresh cobalt bits. Pick a bit 1/2 the size of the final bit for your pilot. This stuff doesn't centerpunch really good. So if you use a hand drill, your going to have to hold it steady to start your pilot hole.

Once its going, hoze it down with your favorite lube. Mines WD 40. I drilled with my right hand, and kept a steady stream of WD 40 going with my left hand.

Use a significant amount of force to keed the chips flying. If your too timid, you'll heat up the drill and dull it. So press firmly and the bit will eat right through it.

The only tricky part is threading in the probe adaptor, as its an uneven surface, and engaugeing the threads right is a little putzy. Don't rush it and you'll be all right.

Some one used the support bracket stud hole (right above the thermocouple in the photo below) as their thermocouple hole too. If your nervous about drilling in the center of the manifold, you could concidere that location too.

As long as you have the manifold off, you might want to have it machined flat accross the port flanges too.

GTD. · « **Reply #14 on:** May 09, 2008, 10:24:42 am »

Quote from: "Vincent Waldon"

Dude... you're killing me... I've been looking for a VDO ambient temp gauge for decades. :wink: And it's even in Celsius...

Sigh.

Took me ages to find one, swapped it for a set of the standard 3 VDO guages from an Audi 80 Coupe came with a matching volt meter and 10 bar oil pressure gauge but I sold them on.

Some SAABs havea ambient temp gauge but have SAAB instead of VDO even thoug they are a VDO gauge.

Going to see if it works using the VDO sender out of the wing on a mk2 GTI (the one for the MFA) might fit 2 sensors with a switch to change sensor from ambient to intake or may fit 4 so can flick between ambient, intake, pre intercooler and post intercooler as well.