Broken Stud - Update

[James G.]

It looks like with our resources and skill mix we are going to try the helicoil "fix" and bring it back down to using the standard stud size. The only concern now is how to drill the hole 90 degree straight, and will there be enough meat in the head to take this drilling. We were trying to think up a way to align the hand drill for this "straight" hole. One idea I had was to drill the head bolt pattern for two studs in a 1.5 inch channel and a third over #5, the broken stud hole. The two would hold the channel while the third hole would guide the drill.

Any experience out there you guys willing to share with us before we get started. Remember this is all being done "free of charge" for a friend! We just want to get this coupe running for sale. The family needs the $!
All ideas are welcome.
Thanks,
Jim G.

[Tom Wesenberg]

Drill guides are made to keep the bit 90* to the block. I found one at a garage sale for a buck.

[Bruce of MN]

These look good
http://www.mcmaster.com/#standard-dr...shings/=oeghp5
click on the removable ones.

[Pete / MA]

http://www.snydersantiqueauto.com/4923

[George Miller]

Originally Posted by 1930 coupe

I put the head on and put a bushing in the stud hole in the head to keep the drill bit centered, then drill through the head stud hole with a bushing in it.

That is the best way to do it. It works every time. Even us machinist would have trouble tiring to get the hole in the right place, and square to the block with out a guide.

[Ed Northrop]

Sponsored Links (Register now to hide all advertisements)

I use a mag drill line it up and when you turn on the magnetic base you cant move it. The local tool rental co has these as they are used in construction a lot I have done several this way.

[eagle]

Maybe there is more history here as your question hints at previous posts? Anyway, I would use a reverse drill bit smaller than the stud. It may just pull out the old stud.

[Ray64]

Sears has drill guides and they aren't that expensive.

[Dave in MN]

I have tried the bolt on drill guides and they do not work as well as using the actual head. A 29/64" drill bit fits tight enough in the head without a bushing and is the exact size you need for the 7/16" Helicoil. You can not get more accurate than using the actual head for positioning. Be careful to gauge the depth of existing holes and then match the depth with your drill bit. Use lots of oil and be careful as you approach depth. The last bit of the head stud often breaks loose and spins under the drill bit. If you feel this, stop and try to remove it before finishing.

[Mike V. Florida]

BUY A GOOD TAP!! The common taps sold are H3 taps and are over size.

[Dave in MN]

Originally Posted by Mike V. Florida

BUY A GOOD TAP!! The common taps sold are H3 taps and are over size.

Mike is suggesting this tap for chasing the threads on the balance of the block holes for the studs. Good advice!

The correct tap for the helicoil insert is sold with the kit from most of the suppliers.

[Kurt in NJ]

The previous post on the subject said that you had a oversize stud that pulled out ---that would be a 1/2 x 13 thread, the hole is already larger than the size for a 7/16 x 14 helicoil --or so close you would not have enough for the helicoil to hold ----that is unless you are going to helicoil for 1/2 x 13---

This 1/2x 13 stud(oversized thread stud) pulled out would leave a 1/2 inch hole ---this hole is already getting pretty close to the waterjacket, normal threads exert an outward force along with the force in the direction of tightening, if the metal surrounding it is too thin to contain that force it will crack ---this is why i referenced this site -- http://fulltorque.com/

What sized drill fits in the hole you have in the block without cutting any metal ???---in other words what size is the hole in the block now? ---the 1/2x13 helicoil takes a 17/32 drill bit ---if this fails you would end up with a hole near 3/4 that will have no easy repair

A head for a drill guide is the best for most people, even a cracked head works, if you are drilling for a 1/2 x13 helicoil the head will need the hole drilled out

[Brentwood Bob]

Look at timesert. It is an improvement on the helicoil. Bob