Stripped head bolt hole in block. TAP with heads still on?

ozanracing · Feb 9, 2007

Last in my list of problems is this:
A head bolt (lower) stripped the block's threads when approaching 80lbs TQ.
When I went to re-torque it hot, it let go.
So what I want to know is:

1) Should I use a helicoil? Or drill it out then just tap it? (I haven't done this before.)
Can this be performed with the head on?
It would take like 5 mins, but to take the head off...gotta get a new gasket, wait for shipping etc...

I thought that the metal shavings would get carried through the water passages (since the lower head bolt passes through the water passages) and possibaly clog the water pump/radiator.

Anyone else have this happen? What did you do?
THANKS!

ozanracing · Feb 9, 2007

Read this off of timesert.com

"Yes Spark plug repair can be done without removing the head by placing a heavy grease on the step tap flutes to catch the chips. TIP: mechanics have mentioned that using a shop vac with a plastic tube taped to the nozzle end works well for removing any stray chips left over."

I wonder is this applies to head bolt-block threads?

ozanracing · Feb 9, 2007

So I would tap it to a 1/2" bolt...My heads are already drilled for 1/2" bolts so....
What pich? And what length insert should I use?

Or could I heli-coil it back to standard 7/16" size somehow??

superhuaman · Feb 9, 2007

heli-coil should work

i would recommend removing the head, but you could probably get away without it.

stang&2Birds · Feb 10, 2007

Heli-Coil Install. Olds Quad 4 head example.
http://www.veryuseful.com/GM/tech/heliCoilInstall/

So, this bolt hole does NOT have a solid bottom? If that's the case, then you can NOT use a heli-coil. A heli-coil will just unthread into the water jacket as you tighten the head bolt down.

Also, this a a bolt hole in the BLOCK? Right? If that's the case, you MUST remove the head. There's no way you could accurately drill and tap with the head on. All you'll do is end up ruining the block AND head.

stang&2Birds · Feb 10, 2007

BTW: Yes, you'll want to use a timesert. See their video for install instructions. Timeserts are much better then a heli-coil! But, they are more work, cost more, and the local auto stores rarely have them.

Also, you must be VERY careful with the counter-bore!! It MUST be parallel and it can NOT be too shallow (then, the time-sert would be above the deck and the head & gasket wouldn't seal).

From:
http://www.timesert.com/html/faq.html
1. What are the specific advantages of TIME-SERT over Helicoil?
The TIME-SERT® inserts have a flange, which will give them a positive placement on installation for “accurate specific depths”. This ensures that the insert does not wind down into the threaded hole. TIME-SERTs are solid bushing and self locking. TIME-SERT being a solid bushing insert gives it added strength. TIME-SERTs have no messy prongs to break off down in the hole which can be a problem in deep holes. TIME-SERTs are self-locking having an actual locking feature which will prevent them coming out when a bolt is removed, again adding to the advantages over coil types. TIME-SERTs are timed internal to external, which give them a thin wall for tight applications but added strength over the coil styles.
Thin wall, Solid bushing, Positive placement, Self locking, Steel bushing.
Customers have asked if they may also use Loctite® adhesives for additional strength. Yes you may due to the solid wall design, there is no danger of loctite passing thru the threads of the insert and locking up the bolt as in coil types.

Very Quick reference on how to install a time-sert.

superhuaman · Feb 10, 2007

ah, my bad. ive never stripped threads on anything "important", just lawn mowers lol

stang&2Birds · Feb 10, 2007

ozanracing :

I can't even get a page to load on the "other" site because of it's POS reliability web connection.

You do NOT want to use a keensert! IMHO, keenserts are for *soft materials only* (like aluminum). For aluminum, keenserts are nice and often the way to go.

Also, you'd *never* want to use a keensert on a hole that goes into a water jacket. You're asking for a ton of problems!!

Your other option besides the timeserts is a full-torque *FFB* series insert.
http://fulltorque.com/ffb.htm
http://www.fulltorque.com/pdf/Full-Torque complete Cataloog 2005-F.pdf

They are made specifically for holes that go into a water jacket. But, I don't have any personal experience using them.

ozanracing · Feb 10, 2007

Anyone used ezlok? http://www.ezlok.com/InsertsMetal/index.html
Thanks for the replies.
I guess I should go take that head off....Again...
So I would like to stay with a 7/16" bold if I could...

I wish I could just use this:
View attachment 404357

ozanracing · Feb 10, 2007

Okay If I go with a timesert, 7/16"-14, what depth should I get?
My ARP hads bolts are Like ~2.8" or so, here are the depths listed from timesert.

.600
.870
1.000
1.250

I'm thinking the .870" sounds rigtht...

stang&2Birds · Feb 10, 2007

No, you can *not* use ezloks or form-a-thread. Sorry.

Form-a-thread kicks @ss in LOW torque applications that do NOT have a lot of thermal expansion!

Ezloks are *not* a good choice on a *through* hole in an application that has a lot of thermal expansion. You have to worry about 3 main things:
o Through hole, no bottom.

o Water *tight* install that will stay water tight and can withstand the deterioration that will happen with contact with water (any spring type of insert will not hold up).

o A "large" amount of thermal expansion along with a high torque requirement.

The full-torque *FFB* is the best. But, my guess is that you'll need $$ install tools and the FFB types are more sensitive to a non perpendicular hole. For a shop, they are the best way to go.

Or, the timeserts with lock-tite thread-lock between the insert and the block. That will help to make that contact area more water tight and will help take up the space difference that will happen as the block, insert, and bolt all expand/contract at different rates. Of course, you *must* always use sealant on any bolt that goes into a water jacket. People have their preferences on the type of sealant.

TheUser · Feb 11, 2007

I read somewhere that a bolt reaches maximum holding capacity at 1.5 times the diameter; beyond that is just excess, but doesn't hurt anything. You'd only theoretically need .656" of thread, so I'd say you were right on w/ the .870 selection.

Good luck!

FWIW, I used the wrong pitch tap when chasing my threads in my block. Didn't realize I had done it until I finished 4 of the top head bolt holes on my block. Ended up heli-coiling those 4 holes. I'm also using head studs, so that probably helps relieve some of the stress on those holes.

ozanracing · Feb 11, 2007

Well I guess I'll be trying to get a 7/16"-14 timesert, .870" depth come monday.

Only concern now is, should I drill it with a drill, or take to this place in town, "Toby's engine machine shop" and have them do it. I've done everything on this car, even all the way down to boring and honing the block, but I just wonder if they have the tools to drill perpendicular to the deck....I wouldn't want to drill the hole "crooked" and have it ruin the block!

That is the reason I thought I might want do drill/tap the hole with the head still in place- It would act as a 'guide' for the bits....

?

ozanracing · Feb 11, 2007

So what do you guys think, try to drill/tap it myself or take it to a machine shop?

TheUser · Feb 11, 2007

I did mine myself (my drill has a level on it) and I still ended up getting one a little off, which made the stud a hair off, but I still managed to get the head on. This one is your call. If you're comfortable and willing to risk it all, do it yourself AND BE 100% SURE YOU KNOW WHAT YOU'RE DOING.

Hauling a long block to the machine shop is going to be a pain in the ass though, just so you know. I hauled my block to the machine shop with everything except heads, intake, and timing cover and it's HEAVY - probably around 250-270 lbs. The crank alone is 50 lbs and the block is supposed to be about 180 lbs I think.

Anyway, if you do drill it, since that goes into the water jacket, you'll definitely wanna clean the shavings out either with a magnet or water or something.

ozanracing · Feb 11, 2007

I was just going to trailer the whole car there, maybe take the head off if they cant do it with the head on...

superhuaman · Feb 11, 2007

wont they need to put the block up under like the drill press or something? to get the hole perfectly straight?

ozanracing · Feb 11, 2007

See, that's the thing, I don't know. If that's the case I'll just drill it.

stang&2Birds · Feb 11, 2007

Machine shop. But, you'd need to take the block out and give them a *bare* block to make sure they do it on a machine.

ozanracing · Feb 11, 2007

I think I'm just going to do it myself.

Stripped head bolt hole in block. TAP with heads still on?

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