So I've looked everywhere and could not find a concrete answer as to how to tackle my problem. I tried searching the forum and i've found a few posts regarding stripped threads but I didn't understand anything (I'm really new to the mechanic scene.) Basically my c5 vette overheated, i tried changing the little things first, ie the thermostat, filters, oil, coolant and finally took it to a shop for a flush and they said it was the head gaskets. To change the gaskets, I was quoted over 1.5k and well quite frankly I didn't have the capital nor if I did would I want to spend that much. So I decided to tackle the problem myself. So I took a few days off work and took off the heads. Everything was going fine until I tried putting the heads back on. I tried to torque the bolts but some didn't give enough. So some of the bolt holes had the threads stripped and I don't know what to do. Some mechanics say get a new engine block, some people say helicoils, some say timeserts. I am leaning towards the helicoils because the timesert kit is pretty pricey and I have no clue as to where to find someone who has the kit and/or knows how to do it. I do understand that the helicoils may not last that long but I do plan on replacing the engine when i get back from deployment next year. So can anyone help me with the sizes i need for the helicoils? or the right kit to buy? Also on how to go through with it; I've seen many videos but if anyone can dumb it down for me step by step it would be greatly appreciated! If this problem has been addressed somewhere else, please redirect me there, any help is greatly appreciated!

 

Your title says header bolt threads, but your description sorta says head bolts. Assuming you mean head bolts, the below is offered:

Though all thread inserts are not alike, they all have a similar installation procedure, you have to drill an oversize hole then tap it for the OD thread pitch of whatever insert you plan to use.

The head bolt thread pockets in the block are threaded pretty deep, so I'm not sure a Timesert would provide enough thread depth. However, two Helicoils might.

A Timesert is a soliid piece, a helicoil is like a spring, but from a thread strength and whether they last is more of an issue of proper install rather than a superior design of one vs another.

At this point in time, the price difference of the part is not your biggest problem. You will probably spend more than you think getting this right. that being said it is worth a try before buying a new block. I suggest going to a good automotive machine shop and talking to them. They may have a drill and tap guide that would make the oversize drilling perfectly along the axis of the original hole. Personally, I would design a fixture with a drill bushing to make sure the tap drill goes exactly where I wanted it, since I would be drilling with a hand held drill. Ditto for the tap, I would design a bushing to send it down the bolt pocket hole correctly.

If that is a daunting task for you then I would negotiate with one of the machinists for a couple hours of his time to come to your car. You might find a guy that would do it on his own time for a couple of Benjamins and a cold 6-pack.

Oh yea, before you put new bolts in, you need to be able to see the bottom of the bolt pockets in the block. The least bit of dirt or antifreeze in these holes and you will bust the block. THEN you ARE buying a new block

 

with Brian

I just went through this with my sons 99 XJ

The above is exactly what to do and solid advice

Regards
Chip

 

Thank you very much, I think I'm going to keep looking for a machinist to help me with it. Not sure if I can guide the drill perfectly through myself.

 

How many head bolts did you strip out? I haven't compared the price of the two different products but I think it would be better to invest in the that will produce the best long term results. The head bolts have to hold quite a bit of torque and if a helicoil loosens a little bit you could blow another head gasket and be right back to square one. As another stated; make Damn sure the bolt holes are clean of everything and all water before trying to thread the new bolts in. I blew mine out with air, then sprayed with brake clean, then air again. Then I went back through every bolt hole with long Q tips to be extra certain there wasn't any liquid left in the holes. And I was glad I bought ARP head bolts as I had to pull the heads again a short time later and I was able to reuse the head bolts.

 

To the OP, are you sure you stripped the threads?

You mentioned, "I tried to torque the bolts but some didn't give enough". Keep in mind, the head bolts thread into blind holes. If you got any liquid in these holes, which is very easy to do, A) the head bolts won't properly seat; and B) you run the risk of cracking the block, as the trapped liquid tries to find someplace to go, as the bolts thread in.

You may want to go back and check things a little more closely...

 

Helicoils work ok in most cases. However the head bolts take some pretty good torque and I've pulled the spring out a couple of times. I had a 454 with a stripped harmonic balancer. You can't pull the dampener on with Helicoil threads. But you can beat it on then torque the bolt.

In some cases you can drill, tap, then use an oversized bolt.

 

Yeah I cleaned the holes with air pressure but I will do it again before i attempt anything. I'm pretty sure i stripped the threads because when i pulled out the used bolts, a coil came out with it. There are quite a few stripped holes. I think there was 5, I have to check again whenever i get the chance to. I found one place that would look at my car but they said it would be around 300-400 bucks which i think is kind of high but idk. I really want to go back home and do this asap but i don't want to rush something and risk ruining the block completely.

 

I would use ARP head studs instead of bolts. Studs are installed unloaded by hand so that the block threads only have to support tension loads when the head nuts are tightened. Studs are reusable and a torque wrench is used to tighten the head nuts to a torque value instead using a degree tool.

 

I highly suggest the OP logs on to the Timesert website. There's a LOT of good info there, including info on a guide plate they make, specially for repairing stripped cylinder head threads. They've posted a video showing how it works.

 

This is one job I would make sure is done correctly. The head bolts require a specific torque setting if not done correctly can cause some issues. Also, the head bolts are not reusable, not sure if you tried to re-use them or not.