Tips on drilling a pyro hole in exhaust manifold

[Diesel_brad]

I'm going to drill my manifold tonight and was wondering if anyone had any tips for drilling into cast iron.

I'm planning to drill into the top of the driver side manifold between the back two cylinders.
Archie

DO NOT DRILL INTO THE TOP of the manifold. Drill into the lowest point on THE BOTTOM. It helps a lot if you have the truck running, it will help blow any metal shavings out the drilled hole. Like others stated, do NOT USE LUBE

 

[gatorman21218]

and if u dont have a turbo dont worry about shavings no turbo means they will blow right out its much more fun that way and if you have a turbo id consider post turbo for youre location

I would still put the probe in the manifold because you want the closest reading you can to the exhaust valve. That way the temp is the most accurate and will tell you when you need to let off of the go pedal. A turbo will cool the exhaust and if you have it post turbo, your reading will be way cooler than actual temps. That could possibly trick you into thinking your temp is fine, when in actuality it is in the danger zone

 

[typ4]

Hopefully you are done and it is working, I wouldnt center punch it because of the brittleness, and the very general rule on NPT taps is run it in all but 4 threads of the tap.
Read that in a machinist handbook many moons ago and it has worked well so far, except on chinese taps but they dont count.

 

[Ataylor]

Probe is in

I finished last night around 1:00 am. I did center punch. That was before I read the post about cast iron being so brittle. I couldn't hit it that hard anyway because there was too much stuff in the way.

I tapped down until there was 4-5 theads showing on the tap and cleaned the hole out with a small bottle brush. I don't have a turbo, so the shavings will go to the muffler.

The pyro adapter went in with a little antiseize and is a tight fit with 3 threads showing.

I can't wait to fire it up, thanks to all that posted tips. I really appreciate your advice.

Archie

 

[subway]

nice looks just like mine

 

[hesutton]

Nice job! That is clean and a good install. I agree with the antisieze. Even if you never plan on removing that bung, at least you know you can.

Heath

 

[MIDNIGHT RIDER]

Nice job! That is clean and a good install. I agree with the antisieze. Even if you never plan on removing that bung, at least you know you can.

Heath

^^^ Listen to this guy; he is an expert when it comes to holes; just ask anyone around here.


I am glad you thought of the anti-sieze; I use it so automatically that I forget to mention it to others.

 

[Agnem]

Nice job! Did you drill with only one size bit, or did you use multiple bits?

 

[MIDNIGHT RIDER]

DO NOT DRILL INTO THE TOP of the manifold. Drill into the lowest point on THE BOTTOM. It helps a lot if you have the truck running, it will help blow any metal shavings out the drilled hole. Like others stated, do NOT USE LUBE

I don't recommend installing the probe pointing upwards in the bottom of the manifold.

It has been my experiences that, for consistently accurate readings, one wants the probe pointing as straight down as possible.

Reason being, soot will continously collect on a sideways or bottom-mounted probe and the readings will gradually become lower and lower as the soot insulates the probe.

I had no choice but to install one sideways and it forces me to remove and clean the probe about every three months.

The top-mounted ones that hang straight down never gather soot.

 

[hesutton]

^^^ Listen to this guy; he is an expert when it comes to holes; just ask anyone around here.


I am glad you thought of the anti-sieze; I use it so automatically that I forget to mention it to others.

Good one Damon.

I'm the same way. I'm a big fan of anti-sieze......... copper based especially. I used almost all of a new bottle on my crew cab project.

Heath

 

[Ataylor]

I drilled with a 1/8", 3/16", 1/4", then with a 21/64" (which is .011" smaller than a "R" drill bit). I couldn't find a hardware store that had a "R" drill bit and I had a sharp 21/64".

I have always had better luck and cleaner holes drilling a small pilot hole then working my way up to the desired size Then I tapped using Rapid Tap fluid.

Archie

 

[MIDNIGHT RIDER]

I'm a big fan of anti-sieze......... copper based especially.
Heath

All I can find around here is the silver stuff; nobody ever has the copper kind.

I used to know why there were two different types, but that knowledge has slipped past me.