34 Spun head stud

[BobWatts]

Trying to get the 34 Cabriolet that's sat for 15 years or so back to life I had a head stud spin while checking the torque today.
I've tightened studs many times and recently checked the heads on 2 Model A's and 2 other Flatheads with no issues at all using a Van pelt sequence chart.
At what felt like a lot less than 50 pounds 1 spun and now I'm afraid another has broke loose as well.
The first one unscrewed from the block easily with the coolant pouring out after it.
What do I do now?
Thanks!

 

[RalphM]

Looks like you'll have to pull the head. No other way to get in there and replace the damaged threads.
It may be time to replace them while it's off.
I had an engine(Subaru alum block) one time that stripped a stud while I was torquing head, pulled it down and fixed hole only to have it happen again on another hole. This happened twice. I would have saved time by doing all the block holes on the first tear down.

 

[BobWatts]

Thanks Ralph I figured I'm looking at a heli coil.
There was about 3/16" thread showing above the nut I wonder if there's any chance epoxying it back in would work.
The other studs torqued ok hopefully they'll hold.
My lucks not going well I think I'll search for a qualified shop to put the heli coil in if that's where I'm headed.

 

[RalphM]

Heli coil's are ok, but there is a better one out there now. The name evade's me now, but do a search on past threads on thread repair.

 

[Ronnie]

Heli coils work well there are 100's of them used on an aircraft engine repairs.There are other alternatives as well.

R

 

[tubman]

I think "Time-Serts" are what you are thinking of. I've used "Heli-coils" a couple of times successfully, but these are supposed to be better. I think they need a little more "room" than a "Heli-Coil" which can be problematic in some locations.

 

[TerryOH]

Do you suspect the threads in the block are bad??? Maybe the nut is tight on the stud and the stud was not tight in the block. If the stud came out of the block and the nut is still on the stud maybe all you need to do is free up the nut in a vise, drop coolant level well below the block threads, spray a cleaner to remove traces of antifreeze in the threads, reinstall stud with clean threads and a good coating of Permatex stud sealer. Use two thin check nuts back to back and install the stud until becomes tight, let it sit over night and then try to install the proper head nut and torque. A new stud and nut may be good idea. Make sure the stud is the proper length. You should be able to do this with the head installed.

 

[GOSFAST]

Trying to get the 34 Cabriolet that's sat for 15 years or so back to life I had a head stud spin while checking the torque today.
I've tightened studs many times and recently checked the heads on 2 Model A's and 2 other Flatheads with no issues at all using a Van pelt sequence chart.
At what felt like a lot less than 50 pounds 1 spun and now I'm afraid another has broke loose as well.
The first one unscrewed from the block easily with the coolant pouring out after it.
What do I do now?
Thanks!

Hi Bob, if it turns out the repair is needed stay with the "tried-n-true" method of the original heli-coil, it would be the best for this type repair!

We use the "Time-Serts" here also but when finished there will be some protrusion above the deck surface. This can also be corrected but would require a c'bored section AND you'll still have a larger "footprint" on the deck. These decks are already on the "thin" side!

(Add) I cannot say how important this one fact is: the repaired hole must end up exactly 90* to the deck surface? We would never attempt this fix by hand.

On any new builds we get to avoid this particular issue during final ***'y when mounting the block plate for finish honing. We run the torque up to 80# for testing only. If it passes here it should be fine with the final torque numbers on ***'y!

If you have some "savvy" you can use the heli-coil tooling itself to make a "quick-n-easy" fixture to help with keeping the hole straight, it's actually fairly easy!

Thanks, Gary in N.Y.

P.S. Not sure if you are near any conventional type machine shops but many generally have a magnetic drill press, makes for an easy fix. Here's a shot of our drill press doing the repair on the block!

 

[BobWatts]

The nut spins easily on the stud and with light torque the stud pulls out of the block so it sure seems like the threads are bad. I've drained the block and will proceed with removing the head. At my business we've rented magnetic drill presses in the past and I'll talk to my guys about that.
As I try to get my Dads cars back on the road after the long storage I'm trying to do all I can myself as he would have and find I'm taking one step forward and two steps back a lot but the moral support really helps me stay motivated.
Thank you!

 

[Flatout]

I thought I had pulled the threads on several studs on a '34 engine when torqued them. It turned out that the threads on the nuts had failed. I couldn't see that when turning them with a socket on the torque wrench.
Use a box end wrench to see if maybe that isn't what's happening to you.