Electric drill be forward speed clockwise or reverse speed counterwise?

[dmorgan]

I am in the process rethreading the threads in the cylinder block hole due to stripping threads inside the hole. I will be using helicoils for the cylinder block. I have a LEFT HANDED drill bit to drill inside the hole prior to tapping and putting in the helicoils.

My question is the electric drill be forward speed clockwise or reverse speed counterwise while drilling inside the hole?

[Frank Reiner]

"Electric drill be forward speed clockwise or reverse speed counterwise?"

Yes, and yes.
Forward is CW, and reverse is CCW.
Observation would answer the question; pull the trigger.

[97 SL320]

It depends if the observer is looking at the drill chuck or the flat end of the drill bit.

If looking at the flat end of a standard RIGHT HAND drill bit, the proper direction is CW , the drill chuck needs to turn CCW to make this happen.

If looking at the flat end of a LEFT HAND drill bit, the proper direction is CCW , the drill chuck needs to turn CW to make this happen.

The larger question is why are you using a left hand bit to install helicoils? The bit will work if it is the exact size specified but what you are doing is uncommon. Be sure the drill diameter matches the drill size stamped on the helicoil tap.

A few things. Don't bury the helicoil insert into the bottom of the hole, the last few threads are tapered and you will end up grabbing / binding the bolt when you install.

The top of the helicoil needs to be 1 thread below the surface otherwise the coil can come out of the thread.

Be sure the bolt you install won't bottom out in the hole / grab the tapered lower threads, wind the bolt in by hand and make sure this is less than the thickness of the part you are going to bolt on. It is possible to have the bolt tighten up but not provide any clamping forces.

[dmorgan]

I did not need to drill afterall. Just straight to tapping the threads and put in helicoils. Works great and still holding up after tightening with valve cover bolts!!