I am getting ready to install the Quadzilla Commander on my 05, 3500, 5.9 Cummins. On page 6 of the instructions Step 1 says I am to drill a 21/64 hole into the exaust manifold. Step 2 says to thread the hole with a 1/8 NPT tap. Maybe my math is screwy but I think a 1/8 tap will fall into a 21/64 hole.

Has anyone else had this problem or am I residing in the twilight zone?

21/64 - not near as big as it sounds. Comparatively it is close to 11/32 which is a little bigger than 3/8.

Oh, and an 1/8" tap is a lot bigger than 1/8" inch. 1/8"NPT quite different.

Whew! Thanks for the info, I guess I should get the tap and go from there.

I'd also recommend that you start with a small bit and drill a pilot hole and work your way up with one or two progressively larger bits before using the 21/64th bit.

Just my 2 cents!

Thanks EDR, I'll do that. I read about diong that on another post and it makes sense. I really appreciate the help here.

I just installed a pyro on a buddies truck. Do yourself a favor: Drop the turbo & block the turbo inlet (exhaust manifold side) with a piece of cardboard. The extra hour or two will save your turbo. Many will claim this is not necessary. I'd rather not chance an $800 or more turbo.

Using the following steps at your own risk:
1) Let truck cool overnight
2) After truck is cool for 2-3hours, spray nuts with PB blaster or similar penetrating oil and allow soaking overnight; respray 1st thing in the morning.
3) Using a 15mm crows foot wrench and impact, loosen topside turbo nuts. You'll only get ~1/16 turn, but they will be loose enough to get an open end wrench to sping them loose. Remove only ONE nut; this will support the turbo.
4) Using 15mm 1/2" drive socket on ~24" extension with an impact, (A 15mm 3/8 drive socket is not long enough and a deep well socket is too long) loosen and remove underside turbo nuts.
5) Using a 9/16" socket, remove the exhaust hangar from the transmission bell housing. This will allow the turbo to hang down ~2".
6) Insert a piece of cardboard on the turbo flange, preventing any metal chippings from entering the turbo.
7) Drill the exhaust manifold such that the hole for the pyro is right over the vertical pipe leading to the turbo; this will allow the shavings to fall right onto the cardboard blank on the turbo. I stepped up through three drill sizes (1/8, 1/4, and 'R'). Cast iron is easy to drill; just be sure to use a center punch and sharp bits.
8) Using compressed air at a LOW pressure/volume, blow out the chippings.
9) Reassemble in the opposite order, removing the cardboard at step 6. In most cases, the turbo inlet gasket is reusable. You can replace it, but more work is involved. See the service manual for guidance. The problem is that the turbo studs do not quite clear the exhaust manifold.
10) Torque the turbo nuts to 32 ft-lb.

HTH

Tony

Hey Tony, when are you going to hook me up and install my pyro[laugh]? How about the whole set up like yours with the switch to toggle between different monitoring points?

graham, we'll talk after the weather imrpoves!

I only did it because he wanted it installed for his wife's birthday on Sunday.

just bustin your chops. Did you put it in Greg's truck?

No...another buddy.

I am getting ready to install the Quadzilla Commander on my 05, 3500, 5.9 Cummins. On page 6 of the instructions Step 1 says I am to drill a 21/64 hole into the exaust manifold. Step 2 says to thread the hole with a 1/8 NPT tap. Maybe my math is screwy but I think a 1/8 tap will fall into a 21/64 hole.

Has anyone else had this problem or am I residing in the twilight zone?

Hi the information i have is to drill a 5/16 hole using a 1/8 npt (pipe tap) with 27 thread per inch. Or a LETTER BIT NUMBER Q..from the center of the manifold go 5/8" off center.
to the left side. (ensure you are able to catch most the shaving)

I am going to be installing my this week just want to confirm that my warranty will not be affected first???. i have good date c/w picture

I installed mine pretty much per the instruction with the commander and had no problems. I used the size of drill bit that was stamped on the side of the 1/8" NPT tap. It was not the size in the commander instructions, I think it was 1/64 different. I drilled a 1/8" pilot hole first then used the bigger drill bit. Left the truck running when drilling and just took my time. I didn't have any grease or cutting fluid so I just dipped the bit in 10w30 several times. There was a number or letter stamp on the top of my manifold where I needed to tap so I used a 4" angle grinder and ground it smooth so it wouldn't affect the drill bit. You will be surprised how much pressure the exhaust is blowing out of the hole when you drill it, I don't think any particle has a chance of going anywhere but out the hole. I did not leave the truck running while tapping, but did keep oil on the tap to help cut threads and catch any particles if they broke loose. Take your time tapping and back it all the way out frequently. It will get pretty hard toward the end. DO NOT FORCE THE TAP. It got to where I was only going about 1/8 turn then backing all the way out. I think I have 5-6 complete rotations of the tap and it is holding fine.

no metal shavings to worry about if you drill when the motor is running. Worked great for me.

the shavings wouldn't be what I'd worry about anyway, it's the remote chance of snapping off a drill bit that would suck, not very likely, but it could happen. It's not that rare to break off a bit, but it would be rare for it to fall into the hole, they should be stuck in the hole. but I still don't like the idea of drilling it while the motor is running. I'd just pull off the turbo and go to work and not have to worry. To each his own though. If I was dead set on not wanting to pull off the turbo, I'd drill it just aft of the #3 jug where the manifold is still horizontal. It's really only going to measure jugs 1-3 in this location tho.

I ended up using a 5/16 bit even though it called for an "R". Left the engine running throughout the drilling and tapping with the exhaust about 3/4 taped off at the tailpipe for added backpressure. Couldn't have worked out better. Only advice I have that I didn't see mentioned is only run the tap down about 2/3 of the way, also when tapping be sure to back out and clean the threads when you start to feel more resistance. Pretty confident nothing got inside the manifold as I could feel the shavings and chips hitting my hands the entire time. Didn't even need gloves it wasn't all that hot.

http://img.photobucket.com/albums/v690/leo_the_great/pyro2.jpg