Anyone Use A Threaded Insert In Block for Head Bolt

Hi all, I want to get a little advice from others who might have done this. My Chevy 250 inline 6 had a threaded insert in the driver rear head bolt location. It was not a heli-coil but a steel insert. I pulled the head for some work and found it was sticking out some. Needless to say, it would not torque up to specs. I was able to remove it. The hole in the block is at 5/8" (head bolt is 1/2").

I was recommended to use E-Z Loc insert which requires a 3/4-10 threaded hole for the insert to be used for a 1/2" thread.

So the question is, has anyone had any good luck with using any inserts for a head bolt location? If so, what did you use?

 

We use Time-Sert products at the shop I work at and have zero issues. When installed correctly and using the correct torque for the bolt size the repair should be as good as new.

 

x2 on Time-Serts, I've been using them for over 30 years. Never had a problem!

 

heli- coil works for me

 

I have a heli-coil in my block right now. It torqued up fine. Maybe whoever installed the insert in yours did something wrong?

 

Keen serts wuill work if you have enough meat to drill and tap or you could just thread the other one back in with some red locktite and let it set up.

 

time cert is a GM approved [demanded/required] repair on the fantastic Northstar Aluminum V8

 

Caterpillar also make good threaded inserts.

 

Many types of thread inserts.
Just make sure you buy one for your application.

 

Just went through this last week when a stud pulled out the threads on my BBC while torqing the heads. I got a helicoil kit and put it in. Torqued right down to 80 ft. lbs. after install, and no problems.

 

I have a question to add to this... I'm going to do a head swap soon. What re the odds of that Heli-Coil giving me troubles during that?

 

Thanks for all the suggestions everyone. They pointed me to a lot of different types I had not heard of. Here's what my research is finding...

Helicoil won't work as the original hole had been "fixed" with a steel insert that pulled out of the block. There is not enough to tap for the size Helicoil.

Time-sert had the same issue with size BUT they also make Big-sert which is basically the same but larger external diameter specifically for fixing holes that other inserts have pulled out of.

E-Z Loc have a large diameter insert so in this case it would work for fixing an already fixed hole.

Keen-sert (aka Caterpiller) are similar to E-Z Loc but also have 4 "locks" that help hold the insert into the hole.

Full-Torque seem to be the top ones on the market as the design actually helps hold the tighter the torque of the internal bolt. This is the only one that will allow a hole with a crack (actually helps pull the crack closed) or even partial hole exposure. Downside is $$$.

Many options...

 

I used to work on OT cars where the head studs would strip out of the block.

I used time serts and never had a problem.

 

ChevyMike, as you noted you are already beyond useing either heli-coils or Timeserts which both use an STI thread. I've used KeenSerts many times in both aluminum and cast iron with good results. McMaster-Carr sells them.Good luck.

 

I would look into why yours failed a second time!
I haven't had the need to do thread repair for a long time and don't remember brand names, but at one job I had we inserted threaded holes in injection molding machine tables. The initial threaded hole in the table would pull out in a few months of operation, but after inserting them they lasted for years. I've seen them fail from repeated use (wear) but never a "pull-out" IIRC we got them from McMaster-Carr.

 

Chevy 250's have a problem with the four corner head bolt holes cracking . Sometimes the crack goes to the cylinder sometimes to the outside of the block. Check for cracks before you spend the time on a repair.

 

Especially the front bolts cracking to the waterpump.

 

No cracks in the block or head (had checked).

I think it was an issue with the original install of the rebuild company. When I pulled the head, it was already partly pulled out and looks like the top of the insert was "flattened" like it was pulled up when they torqued the head originally. I looks like a bad install to me.

I am going to talk to the machine shop on Tuesday and see what they use.

My only issue with doing it myself is getting it squared to the block.

 

Figured I would post a couple pics of what's going on.

This was ground flush before I started the torque sequence and this was at 75 ft/lbs.


The insert that I removed

 

I have a 400 smallblock that I used to run in a race car 25 years ago. It pulled a head stud , which like yours had been repaired before I got it, the resultant hole was too big for the available inserts back then.....and in New Zealand 400 blocks were hard to find and real expensive .
So I made my own insert from a piece of cast iron bar. Turned it to a suitable size, bored it and , then turned a fine thread on the outside. Drilled and tapped the block and screwed it in with 680 Loctite . Then using a block of hardwood for a guide I tapped the insert to correct thread.
For the guide I just faced the block of wood and bored a hole in it then ran the tap in while it was still on the lathe. Once I had it located on the block,the tap ran straight into the hole....probably wouldn't be any good for multiple uses, but it worked fine for the one I needed.
The repair worked fine , reused the block in the racecar and when it was retired from there , it did about 50000 kms in the tow truck, before I converted it to diesel.
It is still sitting there on the shelf waiting for another day..

 

Mike, that is not a normal thread. Are you sure it's 5/8? Ridges and grooves should be equal, they aren't.

 

The internal threads are 1/2-13 and a 5/8" drill fits snugly in the hole left with the insert removed, being that there are no threads left in the block.

 

That looks like an insert for putting machine threads into wood furniture...
Keen-serts are a good choice, red loc-tite in and go on about your rebuild.

 

I was thinking that but was afraid to say it. Check the hole with a caliper. A 1/2 Keensert needs a 3/4 outside thread.

 

I was seriously thinking of doing the Keensert but everything I am finding is showing the external threads for a 1/2-13 internal is a 5/8-11. Trust me, the hole in the block is 5/8".

Info found on Keensert,
"Thread repair insert for use in metal. Installs easily with a standard drill and tap. Once installed, drive pins down with installation tool (item# 12404) to permanently lock insert in place. 1/2-13 internal thread, 5/8-11 external thread, .62" length, 37/64" drill."

 

This shows 3/4...

http://m.grainger.com/mobile/details/?R=5WY80

 

I have repaired screwed up blocks by threading hole with NPT then using common hardware store solid cast iron pipe plugs. Loctite it in, carefully grind off top/excess, then drill and tap to correct thread size.

Had an old bjg block Chevy drag race warhorse, stud pulled/cracked, that I repaired several places with pieces of thick wall gas pipe. Threaded into block, then 7/16" tapped. The thing is still out there in a 55 Chevy doing street retirement for the last 20 years.

 

I guess they must offer two wall thickness as I found the info about the 5/8 tap size on many different sites with specs on the inserts.Here is something I also found from the Grainger site that would concern me.

" Key Locking Thread Inserts Repair damaged threads with a positive mechanical lock, preventing rotational spinout from vibration or torque. For metal applications; not recommended for cast iron or brittle material"

They are saying not recommended for cast iron. Interesting...

 

I saw the cast iron thing too. I guess due to it putting outward pressure on the hole when it locks?

 

Yeah, it's looking more and more that I am likely going with an E-Z LOK insert. It's heavy wall, uses a 3/4-10 external thread for the 1/2-13 internal.

http://www.catalogds.com/db/service...owProduct&category=hvy_crbn_unc&product=329_8