Helicoil tapping procedure

[Guest]

I'm in the process of rethreading a hole in the cylinder head for one of my cam chain tensioner bolts. Using a helicoil kit for a 6mmbolt.

My question is about the tapping procedure. Never tapped a hole before. Is there a technique that's helpful here? I'm assuming that you get the tap started and when it starts to turn hard back it off a bit, maybe squirt a little oil in there and then start in again. Am I on the right track here?

Any tips would be appreciated. Thanks.

[nabrams]

Yes, back off every 1.5 turns and take the tap out and clean it of chips.
Use axle grease (or other grease) to lubricate the tap. It also catches up all the chips pretty well. Do it slow and you'll be fine.

[argonsagas]

I would be a little careful about the one and a half turns. Depending on the material, and the tap, this may be too much.

General rule:

If you feel that the tap is getting tough to turn (seems to be binding) stop and back off. at least a half turn.

Re-lubricate, then try again.

I have never tried grease, only oil. There is a special blend of oil for tapping, and it is recommended if you are doing a fair number of things.

Remember to vacuum, and get everything out.



This applies even if you only went half a turn with it before it started to bind.


NEVER push your luck with a tap.....they can be very, very, difficult to remove after they break.
General ru

[JayH]

Put a rag under the area that you are working on to catch any metal chips that don't get caught in the grease or oil. You did take the tank, carbs, and airbox out right? Take your time and I'm sure everything will be fine.

[BadBillyB]

Re: Helicoil tapping procedure

Any tips would be appreciated. Thanks.

If your only doing one hole, start a bolt in the other hole to use as a guide for keeping the angle correct. Also you must tap the hole a few threads deeper than the heli-coil will be when it is installed. Reason is, the tap is tapered at the end and causes the coil to "shrink" if you dont tap the hole deep enough. This can make the bolt really tight when it reaches the bottom coils. And now for the best tip.....After installing, when you go to break the "tang" off, use the back of a drill bit, one that barely fits into the hole in the heli-coil, and tap it with a hammer handle. The snug fit of the piece, you use to knock the tang off, keeps the bottom coil from being pushed out of place.....I ruined a few coils not knowing this. Finally read the directions on the heli-coil package one day, which is a no-no, and this is clearly stated on the package.......Go figure.....Badbillyb

[RacingJake]

I did the tops of my cam caps early this year. Take your time and you should be good to go. If you can practice on a junk piece of material it might help to calm your mind.

[duaneage]

If you have a drill press available drill a piece of aluminum from home depot with the hole you need and tap it. Then you have a guide you could use to get it started square, the idea being the drill press allows a straight hole to be used as reference.

I threaded rocker arm studs for my small block ford using a bearing cap as a guide to keep the tap straight when starting, then removed the handle to get the bearing cap out of the way to finish the job. They needed to be perfectly straight.

[mark]

Thanks for all the advice everybody...very helpful. I've got an extra 850 cylinder head underneath my work bench I can practice on. Totally forgot about it.

I did the tops of my cam caps early this year. Take your time and you should be good to go. If you can practice on a junk piece of material it might help to calm your mind.