Stripped Head Bolt.

[Bort62]

I managed to strip the passenger side front head bolt hole. It is the one above the water pump.

The Bolt I stripped it with is 3" long. it looks like I was getting about 1/2" engagement.

What I am wondering is, how much more thread do I have down there if I stripped out 1/2" of it, and can I get away with a longer bolt or do I have to helicoil?

a 7/16" helicoil kit is not cheap.

 

[Bort62]

Alright, I got impatient waiting for you guys so I figured it out myself... And here is the info for anyone who needs to know in the future.

The head is 2.5" Thick at that particular head bolt (and probably all the rest).

At a distance of 3 5/16" from the bolt pad, you start to run into the water pump impeller.

So you can get away with as long as a 3 5/16" bolt with washer.

That means that you have a maximum of 11/16" of thread engagement, but actually less as im sure the bolt sticks out the bottom of the threads a bit.

After having stripped out a 3" bolt I was able to get the proper torque on the 3 5/16" bolt, so there was at least a little engagement left after the ~ 1/2" I stripped out. 5/16" isnt a lot of thread, but it seemed to work.

Im not sure how much, but enough to take 70 ft lbs. Now, I haven't really driven the car a ton since then so maybe its not sealing right and the gasket will pop - but it's worth a try.

Helicoil kit for 7/16-14 is 50$ from mcmaster.com

 

[63redtudor]

You can get helicoil kits at NAPA (I suppose others as well) for cheeper than that. I'd say just bite the bullet & buy the kit. Helicoils are are actually a decent way to go & quite strong. Unless you try hard to mess it up, the helicoil will probably last the lifetime of the motor. I use them all the time, but then I'm an aviation mechanic & most parts are aluminum...
Edwin

 

[JackFish]

I've been looking at threaded inserts, and there may be other options for you. I can't offer any experienced with any of them, but here are a few links to look at:
http://www.groov-pin.com/threaded%20inserts/tins.htm
http://www.timesert.com/index.html
http://automotivefasteners.thomasnet.co ... &forward=1
http://www.newmantools.com/kee.htm
http://www.wireinserts.com/Products.htm

 

[ludwig]

Pardon my lack of insight, but why can't you clean up the hole and tap it to the next larger metric or inch size for that one hole? There were about 3 different oil pan bolts on my Mustang when I got it. I cleaned them all up, back to spec except for one and it got the metric screw that came with the car. (I know the pan doesn't get as much pressure/torque as the head.)

So why does it have to be helicoiled?

 

[Bort62]

Good point, but Im not sure if the head will pass a 1/2" bolt.

And I don't have a mill here to ream it with.

It seems to be holding fine so far. About 20 miles on it.

I am a huge fan of helicoils, I just didnt want to have to take the damn head back off and wait for the kit to show up from mcmaster

If the head will pass a 1/2" bolt, then that would be the way to go.

 

[Alabama65stang]

Had the same thing happen to mine. Heli-coiled the block and got the head studs from Mike at Classic Inlines on this site. You can run the studs all the way into the block and use all the threads. Check the length on how far the studs or bolts go through the block because that bolt will run into the water pump. Mine has held up fine since July.