tips for drilling into 1jz head

[barned01]

hoy hoy,
are there any tips for drilling into the alloy head without anything disastrous happening?
i have just purchased a brand new Sutton drill bit from Bunnings but I am concerned it might be too sharp and potentially cause the alloy to crack/break?
do I need to drill on high speed or low speed.(on a battery drill)
do I use some metho to lubricate while drilling?
should I be aware of anything else?

I am drilling out and retapping a weak thread from one of the exhaust bolts.
cheers
Damien

[2jzhilux]

Drill as slow as you can , make sure you centre punch the stud so you dont drill any alloy away just the stud.
The alloy has no chance of cracking as it will be soft as butter.

[allencr]

Head on or off, if it's off, you'd be better off to get a helicoil or one of the newer designs.
The bit, the tap drill size is specified for aluminum or steel/whatever??
You can cut a deeper thread in soft stuff and using a hand drill, even though you've got a HUGE pilot hole, will get a larger size then the bit is, wallowed out & bell mouthed if you're not really good.
To me, aluminum likes fine threads so if you've got a choice, 1.0 instead of 1.25 or 1.5.

[checksix]

Slow with the sharpest bit, and a lubricant is the best! If you are doing a re-tap then a heli-coil is stronger than just rethreading.

[barned01]

engine is still in car, it is the rear exhaust bolt hole that has fatigued.
the stud barely stays in there of its own accord.
I am using the recoil brand sold by CBC bearings (no automotive supplier here seems to stock anything that might be useful so i have ended up at a bearing supplier of all places)
thread is m10x1.25 standard exhaust stud
the kit specifes a 10.25mm drill bit or 13/32 (10.32). As I couldn't find a 10.25, i went for the 13/32. The next size down from that that i can find that would be close is 10mm

As it is I am going to use the 13/32 bit....unless i am better off with 10mm (the next closest size down)

so steps are...???
1. steadily on slow speed with a nice new drill bit, drill out existing hole (use metho while drilling).
2. clean out hole, tap new thread (use metho while tapping)
3. insert coil as per manufacturers instructions
4. pray to god everything was alright
5. ????
6. Profit

[checksix]

13/32 = 10.31875 Can't see where .07 would matter much. Too small and the possability of breaking a tap in the hole would be a nightmare!

[TERRA Operative]

so steps are...???
1. steadily on slow speed with a nice new drill bit, drill out existing hole (use metho while drilling).
2. clean out hole, tap new thread (use metho while tapping)
3. insert coil as per manufacturers instructions
4. pray to god everything was alright
5. ????
6. Profit

This.

I've used recoil and helicoils (same thing, different brand) a lot at work and home and if you follow the instructions and take your time, you can't really stuff up.
Just be sure to read the instructions twice and follow them to the letter. If the instructions specify a drill size, use that drill size. Also make sure you tap deep enough to allow the coil to be inserted far enough as specified in the instructions.

[roadsailing]

Grind the point off the drill if you are that worried about it, you won't need it for what you are doing.

If you are just tapping it and not helicoiling, make sure you use a tap designed for blind holes.

[mr75]

dont know if you have a wurth store or rep around your area but i find their heil coils are the best as they are a solid helicoil instead of a threaded wire. depending on the quality of the helicoil you also may want to use some high temp locktite.

[barned01]

OK drilling done, tapping done, recoil inserted.

Now the instructions don't say anything about it but should i be using an antisieze compound on the stud before i put it back in?

i have permatex aviation form a gasket#3 (brown gunky paste thingy) but should i be finding something more specific if i do need anything at all?

[seamonsta]

If you plan on taking the stud back out every 2nd week use anti seize, otherwise I wouldn"t bother, same for gasket goo, the factory gasket is enough if in good condition.

[beatle]

i always put on antisieze, for that area i would use either a nickle based or metal free type.
or you can just use a dab of oil.

[TERRA Operative]

I always use nickel based anti seize on all exhaust bolts, and anywhere the bolt is a different metal to what it's screwing into.

Makes life SOOO much easier when it has to come apart again.