Drilling/tapping heads

[Quickstop [UK]]

For those of you that have done this to your heads, what setup do you need/recommend?

My Dad has a drill press and all the drill bits and I expect a tap should be easy enough to come by but getting the angle right etc is something I imagine is quite tricky. What do you use? I could probably make an adjustable jig using a template from the stock lower intake. Is this sensible?

I read the link on the Tyclone page and feel I could do this myself instead of having a shop charge me for it. Am I mistaken?

Edit: I read a thread by Necrowolf and he described doing it and said "it's too easy to pay a shop to do it" so if anyone could tell me how to do it, I'd be grateful!

drilling vortec heads for SyTy

Tyclone.com

 

[JSM]

Get 2 flat plates, weld them at an angle to hold the head flat for drilling on the drill press. Drill and tap the plate for 2 bolts to hold head on (through head bolt holes).

Plus you get to practive your welding skills.

You can put a level on the intake mating surface before you drill and shim or have adjustable feet on the fixture to adjust it.

Lets be honest though, if your within a few degress it will function just fine. Most blocks/intakes, etc are milled at different angles during rebuild process, intake bolt seating surface is a cast not a machined surface, etc. Its not rocket science.

 

[Quickstop [UK]]

Re: Drilling/tapping heads

I managed to do this and was asked by another member to do a write up so this is an attempt to do just that.

You will need:

1 pair of good vortecs

Check for cracks!

And this on the other head...

Also needed...

17/64" drill bit for the holes - tungsten carbide worked nicely
1 x 5/16" tap
Cutting fluid - double check this - some say it's not needed but I figured it can't hurt
A block of wood, 2" x 2" at least, depending on the length of your drill shank
A centre punch
Some patience
Some allen plugs or equivalent to plug the old holes.
JB Weld.
A SyTy lower intake manifold and gaskets.

How I did it

This is not a definitive method but it is what I did with limited experience and equipment. There may be better ways to do it. If so, please add your method below.

The trickiest part of this is making sure that the holes are in the right place to match the manifold on both sides so that when you tighten up the bolts, you don't crack the manifold. You need to test, and test, and test fit again. You need to have the gaskets in place. Because the holes are oblique, the height of the gasket will affect where you p lace the holes. It takes some patience but it isn't impossible.

The way I did it was mock up the lower intake gaskets and lower intake with the heads on the block. Ideally they should be torqued down so that they are in the same place as when you finally mount the lower to the truck. However, there is some room to manoeuvre as the holes on the lower intake are larger so some leeway exists.

Once the lower intake is resting on the heads/block (with gaskets), you need to find the centre of two or three holes. Mark these by whatever means you have at your disposal. I used a permanent marker. It can be tricky as the holes point at the manifold itself. A short scribe might be better.

Once you have the centre of the hole marked carefully, remove the lower/gaskets and use a centre punch to start the drill in the right place.

The 2" x 2"

The block of wood is for aligning the drill vertically. It needs to be long enough that you can get a decent grip on it to hold it while you are drilling. a foot is probably enough. Get a decent piece of wood with a smooth finish and use a drill press to drill vertically through the block. Use a bit that is the same size as the one you will drill the heads with. You now have a drill guide so that the holes are vertical to the surface of the head.

At this point, I also drilled another smaller hole at an oblique angle so I could spray cutting compound into the tip of the hole. Don't go too fast with the drill but the cutting fluid really helps. A proper drill will cut through the iron heads like butter.

When drilling, take it nice and slowly. No rush.

Drilled pilot holes for the taps.

Once you have a couple of holes drilled, you can mount the lower intake and mark out the other holes. This takes time and can be frustrating. I mounted and remounted the intake numerous times to try and be as accurate as possible. I was hoping there might be a template out there for the layout of the holes. If I were to do this again, I would probably lay out the lower intake on a piece of paper and then use the intake to make a carbon copy and use that for the holes. I am sure it would be easier. You need to mount the intake on the gaskets first though to get the starter holes. Then use the template.

If you do it how I did it, you will probably find that the intake is a bit tight. Work out which holes are causing the obstruction and you can grind a tiny amount of material off the hole on the intake for clearance. I would rather not have done that but this was my first time doing this. It was a tiny amount of material. If you are more careful, this won't be necessary.

Tapping the threads

If the holes are already drilled then you are committed to tapping as-is unless you are a machine-shop pro and are going to stitch weld the hole and re-site it. I am not and I didn't

The trick with the tap is to make sure it starts straight. There are a couple of options here... eyeball it and hope (not ideal) or make a similar block of wood/guide for the tap to cut into.

I ended up eye-balling it and carefully making sure it was as vertical as possible. It actually worked out ok but the next time, I would do it slightly differently.

Started tapping the heads

After you have done drilling and tapping, clean all the swarf and chips and your heads are ready for the next bit.

Coolant passages

You will notice inthe 4 corners of the threads where you drilled that they penetrate the coolant jacket. You need to block the old holes off using allen plugs and JB Weld. I didn't have allen plugs that size so I spent a bit of time with some all-thread/ studding and cut off 4 short pieces. I filed a notch in each one, cleaned it with brake cleaner and then put JB Weld in the hole. I used a screwdriver to turn the plug and then let it set.

Once set, the heads are done.

Hope this helps. :tup: