# Sticky  When you're torqueing down head bolts and you get that sickening feeling when one of them "gives"....



## BearGFR (Aug 25, 2008)

Yeah, it happened to me and it was my own fault.

Several months ago as I was getting ready to file-fit the piston rings for my currently in-progress build, I was putting on my torque plate for the process. A few of the bolt holes felt "tight" like the threads were dirty. At the time (note that phrase), I didn't have a thread chasing tap set so - despite the fact that there are warnings all over the place NOT to do this - I went ahead and used a regular cutting tap to clean out the threads. There's a reason for the warnings. Doing this will remove more metal from the threads which will make them weaker. Note to self, and to everyone reading this: If you have a job to do on an engine and you find that you don't have the right tool for that job, *STOP UNTIL YOU GET IT! *You'll save yourself a ton of misery. I wish I'd taken that advice. 

Yep, *4 bolt holes pulled out* - of my original to the car engine block - *INCLUDING* one that had already been repaired once with a Helicoil insert. (That's a long story about a boneheaded mistake I made back in 2009 when I built this engine the first time, so I won't go into that now.) The "newly screwed up" bolt holes I was able to repair myself using a TimeSert repair kit. This time I made some locating jigs and other guides to make SURE that I drilled the holes square to the deck and to the correct depth. Timesert's are, I think, better than Helicoils. They're solid "sleeve" type inserts intead of coiled wire like Helicoils are. The bottom few threads of the insert aren't fully formed, so when you install them into the drilled and tapped hole for the repair using their installation tool, the tool "spreads" those bottom threads and that's what locks the insert into place. They work pretty nicely.

But, I had the one hole that had already been repaired once, and it was the hole between the center two exhaust ports, the "back side" of which appears as a dome shaped protrusion into the block water jacket, and is visible if you remove the middle casting plug. 

Putting a repair kit into that already repaired once hole was going to mean that the hole, already drilled oversize for the first repair in 2009, was going to have to be drilled out larger. 
I did the best I could to measure things, and what I discovered was that if I drilled it out for an oversize insert the walls on that bolt boss were going to end up being just under 1/16" thick. Gulp.

I started looking for every different "oversize" repair kit I could find, and they all had that same problem. The hole to install them was going to leave those walls paper thin.
On my original to the car block.

Oh man.

I looked, I talked, I pleaded with various engine building groups on FB.

On one group nearly every person who responded recommended the same kit and it was one I'd never heard of:  "Full-Torque"

These things are genius. They require the same size hole as the other oversize inserts with the same resulting thin walls in my situation, but what makes them unique is the way the outside threads on the insert are cut. Instead of being "regular" saw-tooth shaped threads, the top faces of the threads actually _slant inward towards the insert body _instead of slanting outward like a normal thread does. This means, that under tension, the insert will be _pulling inward_ on the parent metal instead of pushing outward on it like a regular thread would, and the inserts themselves are BEEFY. 

I bought a kit. Pretty pricey, but hey -- this was my one shot at saving this block. One smart thing I did was taking to the machinist and getting him to install it for me.

It worked. Just a few minutes ago I finished installing my heads, with ARP studs, which get torqued to 110 lb. ft. It held. 

I torqued them down in increments of 10 lb.ft., starting at 70 and working my way up. Let me tell you, when I was at 90, 100, 110 I was sweating bullets and the pucker factor was about on 12 on a scale of 10. Is the wrench going to go "click" or is it going to give?

Full-Torque thread repairs. They are the bomb.

Videos: Full-Torque

Bear


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## PontiacJim (Dec 29, 2012)

Bear, what you forget to say, and probably one of the most important things from this lesson (although the tap is a no-no), *Ram Air IV heads use different length head bolts *and several of them are longer than the non-Ram Air IV heads. If you use the standard length head bolts, the ones that are too short will not reach deep enough into the block's blind holes and can pull the threads out and that's when the party begins. 

Typically, the aftermarket aluminum heads are based on the RA IV and will include/recommend the ARP head bolt or stud set. So always inquire if you need any head bolts that need to be used with any aftermarket head. 

And......... if you have decked/milled the block/heads, it is possible that the head bolts can bottom out in the block's blind holes and the head will not clamp correctly even though you torqued the bolts. Torquing the bolts after they have bottomed out can lead to cracking/breaking the blind holes in the block creating a water leak, or worse case scenario, cracking the block.

When using any kind of lubricant (light oil or moly grease for ARP bolts) on the head bolts, put the lube on the threads and under the heads and wipe off with a clean lint free rag, don't leave the grease globbed on the threads or underside of the heads. This leaves just enough of a light coating on the threads. If the blind head bolt hole somehow gets too much oil down into it, the heat from the engine can cause the oil to expand which in turn means a lot of pressure and it has to go somewhere - enough pressure to crack or split the blind hole or even the block. (this according to my engine builder who has seen a couple blocks turned to scrap because of this)

Again, follow the manufacturers procedure when installing head bolts or studs.

Make this a "Sticky" in the *Engine Tuning* section.


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## Baaad65 (Aug 29, 2019)

Or is it a good idea to use studs to avoid these problems?


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## PontiacJim (Dec 29, 2012)

Baaad65 said:


> Or is it a good idea to use studs to avoid these problems?


Bolts are just fine. Studs, from what I read, apply a more even pull on the heads. Just an option and probably used more for racing or when you use add-ons that build more cylinder pressures like turbo's, supercharging, and nitrous. Keep in mind that when removing a head, you have to lift it up and off the studs which could be an issue if you don't have the clearances to pull the head up and off.

I went with studs on my engine - just because, and I also plan on a small shot of nitrous.


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## LATECH (Jul 18, 2018)

I hate to burst your bubble, but will they Hold? I hope so, but that is a relevant question . I hope they hold for years, an you can report back as such. Good luck Bear.


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## lust4speed (Jul 5, 2019)

Just to stir up a little thought, why does ARP recommend 10 foot pounds more torque on the headbolts? Because their bolt is made better? Where is the weak link here? BearGFR knows the weak point very well and it definitely wasn't the stock Pontiac bolts. The weakest area is the cast iron block, and that tensile strength doesn't change with an improvement in bolt quality.

Final torque rating should be what the machinist used when honing the cylinders. Increasing clamping force is going to pull the cylinders out of round. A torque plate is used to simulate eventual stresses imposed by a specific force, and if the shop didn't know you were going to go with ARP's recommendation, then they will have honed the block at the 100 foot pounds torque. The harder you crank on a bolt the more distortion is introduced into the block.

On to only using a thread chaser - should liven up the thread. Now if all you own is a Harbor Freight set of taps I would agree to not go anywhere near the block, but for that matter a Chinese set of thread chasers can also do damage. The threads were cut with a precision tap and that same tap could be run down the threads many multiple times without removing any additional material, and another precision tap with exact dimensions should go down the threads without removing new material. I'd say that rust and corrosion do the damage to threads and the weakened threads are prone to failure regardless of the cleaning process. (Seems that machinist are split on tap vs. chaser about 50/50 so tough debate to win either way.)


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## Baaad65 (Aug 29, 2019)

Maybe different bolt manufacturers have different bolt stretches to keep the tension depending on what the bolt is made out of idk just guessing?


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## BearGFR (Aug 25, 2008)

PontiacJim said:


> Bear, what you forget to say, and probably one of the most important things from this lesson (although the tap is a no-no), *Ram Air IV heads use different length head bolts *and several of them are longer than the non-Ram Air IV heads.


No, I didn't "forget", I just didn't get into that OTHER boneheaded mistake I made back in 2009 when I was building this engine for the first time. But since you brought it up... 

That's exactly how that one hole got stripped out the first time in 2009. I'd managed to find a set of real Ram Air IV #722 heads and was building the engine with them. I didn't realize that they needed longer bolts, especially on the one that's between the center two exhaust ports, and when I went to mock it up for assembly the first time using the same bolts that were used with my original #62's... POP!!.. out it came. 

That was bad enough, but I wasn't done screwing up yet.

I was "in a hurry" to get the engine done so instead of taking my time and making some sort of drill guide to use when drilling that hole out for a Helicoil, I "free handed it" with my drill. Well, guess what? I didn't get the hole perfectly square to the deck which caused that bolt to be ever so slightly tilted. The bolt would start and thread, but it was extremely tight going in because it was pushed up against the inside of the hole going through the head. I had to use a wrench to run it down into the hole, and I'm sure because of that the torque on that bolt was "just a guess".

When I built it "the next time" in 2016 years after one of the #722's had developed a crack and I'd replaced them with the Edelbock's it's running now, I addressed that problem by putting a single stud in that hole and bending it over slightly to make it square. Yeah, I know --- but it worked --- until this last time when it pulled the Helicoil out. Not exactly sure why that happened but I'm assuming it was because that stud had been pulling somewhat at an slight angle instead of square to the deck and thus was probably putting a lot of "sideways" strain on the bolt hole. 

That brings us up to the point where I had to repair that hole the second time, and how I ended up doing it. 

These inserts are really beefy. They're high quality steel and the walls are about 1/8" thick. This one is a blind insert - closed at the bottom. The hole to install it was drilled all the way through and out the bottom of the existing bolt boss, into the block water jacket. The insert itself is installed with a provided sealer so it won't leak, and then pinned at the edge so that it can't turn. Because of how the outer threads are cut, instead of pushing outward on the parent metal like a normal thread would, it pulls the parent metal >inward< against the body of the insert itself just like as if it had a big honking clamp around the outside of it. This keeps it from 'breaking through' what's left of the original bolt boss, which in the 'vertical' direction is still tall/long enough to keep the insert from pulling out.

As far as the studs vs. bolts question that someone brought up, I asked my machinist that very question. Which would be the most likely to hold, bolts or studs? He said studs, because all the stress on the threads from them is straight up. Bolts apply both a pulling stress and a twisting stress during the final stages of torqueing them down, and that's harder to hold - even taking into account the ARP spec for their fasteners calls for a higher torque load. That sort of made sense to me so that's the direction I went and it has worked - twice - once with my torque plate so I could finish file fitting the rings, and again last night when I put the heads on. 

Here's what it looks like from the deck side. You can see the locking pin at the edge:










And from the underneath side, inside the water jacket









Bear


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## PontiacJim (Dec 29, 2012)

Wasn't trying to call you out or put you on the hot seat. LOL Just wanted to make your post complete as I myself did not know that the head bolt lengths were different between RA IV and the other heads. I learned this when I purchased a set of ARP head bolts for my last 400CI build and a couple of the head bolts would not seat - too long. Luckily I did not make any attempts to crank them down more or torque them as they sat up kinda high and the ARP bolts are designed to be used with a matching hardened washer under the head. Told my machine shop guy who did my engine work ( a real idiot who was a Chevy machinist and not a Pontiac person) about my problem and he said just add another washer under the head - which is what I did. It worked without issue. BUT, I did learn later that I had ordered the wrong head bolts because I thought "head bolts are head bolts." Wrong, different lengths. But it could have become a disaster and done damages to my block.


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## Noangelbuddy (Dec 6, 2017)

BearGFR said:


> No, I didn't "forget", I just didn't get into that OTHER boneheaded mistake I made back in 2009 when I was building this engine for the first time. But since you brought it up...
> 
> That's exactly how that one hole got stripped out the first time in 2009. I'd managed to find a set of real Ram Air IV #722 heads and was building the engine with them. I didn't realize that they needed longer bolts, especially on the one that's between the center two exhaust ports, and when I went to mock it up for assembly the first time using the same bolts that were used with my original #62's... POP!!.. out it came.
> 
> ...


Thanks for sharing a painful lesson. Your post may keep someone else from making that mistake. I cringed when you described torquing a bolt and then feeling it “give”. Been there, done that and could only blame myself.


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## ponchonlefty (8 mo ago)

BearGFR said:


> Yeah, it happened to me and it was my own fault.
> 
> Several months ago as I was getting ready to file-fit the piston rings for my currently in-progress build, I was putting on my torque plate for the process. A few of the bolt holes felt "tight" like the threads were dirty. At the time (note that phrase), I didn't have a thread chasing tap set so - despite the fact that there are warnings all over the place NOT to do this - I went ahead and used a regular cutting tap to clean out the threads. There's a reason for the warnings. Doing this will remove more metal from the threads which will make them weaker. Note to self, and to everyone reading this: If you have a job to do on an engine and you find that you don't have the right tool for that job, *STOP UNTIL YOU GET IT! *You'll save yourself a ton of misery. I wish I'd taken that advice.
> 
> ...


bear, i know its a little late but for future builds you can take a dremel or grinder and cut a groove in a bolt and make a thread cleaning tool. glad things worked out for you. maybe time to play the lottery.


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## ‘Vid (9 mo ago)

Noangelbuddy said:


> Thanks for sharing a painful lesson. Your post may keep someone else from making that mistake. I cringed when you described torquing a bolt and then feeling it “give”. Been there, done that and could only blame myself.


Haha yeah this thread is scarier than a Stephen King novel! Yikes!


Sent from my iPhone using Tapatalk


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## Baaad65 (Aug 29, 2019)

You're gonna need a longer bolt...see 🦈


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## Greek64GTO (Dec 13, 2015)

BearGFR said:


> That brings us up to the point where I had to repair that hole the second time, and how I ended up doing it.
> 
> These inserts are really beefy. They're high quality steel and the walls are about 1/8" thick. This one is a blind insert - closed at the bottom. The hole to install it was drilled all the way through and out the bottom of the existing bolt boss, into the block water jacket. The insert itself is installed with a provided sealer so it won't leak, and then pinned at the edge so that it can't turn. Because of how the outer threads are cut, instead of pushing outward on the parent metal like a normal thread would, it pulls the parent metal >inward< against the body of the insert itself just like as if it had a big honking clamp around the outside of it. This keeps it from 'breaking through' what's left of the original bolt boss, which in the 'vertical' direction is still tall/long enough to keep the insert from pulling out.
> 
> ...


THAT'S A DAMN NICE LOOKING REPAIR!


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