taken19

Spent the day at Homestead yesterday waiting for the rain to clear so I could get some good laps in. After lunch, I finally get to stretch her legs. Got around an R8, turn into to 6 and accelerate... Massive engine stutter and vibration. I have to let the R8 by and head into the pits. Sounds like a misfire but no engine codes.

I got home, idled the car and pull plug wires one at a time to determine which cylinder is misfiring - its number 2 (right behind the alternator). I changed the plugs last night, (#2 plug is fouled) no change in engine performance.

Pulled the valve covers for peace of mind this morning and find the intake rocker arm bolt broken. Anybody else ever had this happen or hear of it? This is only my second track day on this motor and it's a stock dry sump LS3. Only upgrades are pushrods, lunati springs and rocker arm trunion upgrade. All work done by Hinson before they shipped me the motor. My gut tells me that the bolt was over torqued.

Thoughts? Is there a way to remove the bolt without pulling the head? There aren't any threads protruding from the head so I'm assuming no.

taken19

taken19

One last thought. Doesn't the trunion upgrade come with their own bolts? The set I installed on my LS2 did, Allen key bolts. These ones are the stock bolts. I wonder if the stockers are a bit too long fr the trunion upgrades and bottomed out (it's not a thru hole after all). The tips of all the intact bolts are shiny, indicating that they may have bottomed out?

After thinking about it, I'm almost positive that the Comp Cams kit comes with different bolts that are a slightly shorter. If this is the case, I bet the stock bolts bottomed out and never clamped the rocker arm. High RPM's would very quickly lead to cyclic fatigue on the bolts. Looks as if Hinson and I will be discussing this tomorrow.

PLEASE correct me if I am wrong so I don't go down the wrong path!

CGZO6

I'd drill a small hole in the part of the bolt that is still in the head, and then use an easyout to get the broken bolt out. Be carefull and don't let any metal shavings fall down the oil drain holes in the top of the head. Use a shop vac too, while drilling to suck up shavings.

Might have just been a bad bolt. Might have been overtorqued. No way of knowing. I'm shure Hinson will send you a new one if you ask.

GL

Edit: I have no knowledge if bolts are correct, but if not = major error.

ErnieN85

take one of the other bolts out and measure the bolt and the depth of the hole that will tell you if it was too long a bolt. the one thing it wont tell for sure is if the bolt hole had something in it which made the bolt bottom early

Painrace

Bolts usually break because they are under torqued!

I have removed them at the track with a punch and a hammer.

There should not be any torque on what is left now. Maybe if you use a reverse drill it will come out. That is what I would try first but as an earlier poster stated, plug all the holes and use a vac. I would also check all of the other bolts. This is not a normal failure.

Good Luck!

Jim

taken19

For whatever reason, the remaining pert won't break loose. Just gives fuel to my theory that the bolts are/were bottomed out all the oxide coating on the remaining ones are gone with smear patterns on the tips. I will measure the bolt length and hole depth in the morning to confirm. An easy out didn't work this afternoon, I will buy the next size up and try again in the morning.

BEZ06

with Jim!!

You say you had the trunion upgrade done - I can't tell from your picture what bolts were used, but they look like the stock bolts.

I have a Comp Cams trunion upgrade kit I'm getting ready to install. It comes with new bolts, but there have been many posts here on the forum that the new bolts are too long, and you should use the stock bolts - so that's what I will do.

The stock bolts which I will reuse have a hex head, and the ones that come with the kit I have come with an allen wrench inset in the head.

I would recommend getting a pushrod length checker to make sure your pushrods are the correct length.

Bob

taken19

Yes, looks like stock bolts to me. I thought the kit had shorter bolts, not longer. If this is the case, it would explain why the stockers bottomed out and led to the failure.

Can anybody confirm the kit has shorter bolts?

BEZ06

Take a look at this thread - it seems to indicate that the bolts that come with the Comp Cams kit are too long, and that the stock bolts should be reused:

http://forums.corvetteforum.com/c6-z...n-upgrade.html


I have the Comp Cams kit and will probably be doing the swap in a couple weeks, but I don't have a stock bolt to measure.

Butt....here's the bolt that comes with the Comp Cams kit that is reported to be too long:




You can see that the bolt that comes with the kit has a 1-3/4 inch shank (measured from under the head). You can also see one propped up in the right side of the picture that shows the allen wrench inset in the head.

So....I don't know what kit was used to do your trunions, but you have a bolt you can measure and see how it compares with the aftermarket Comp Cams bolt that is reported to be too long. If your bolts are a little shorter than the Comp Cams ones, then they're probably stock. If they're similar in length to the Comp Cams ones, then they are probably too long.

Bob

taken19

Thanks Bob, I had Zero issues when installing this kit myself in my old motor. I will measure the stock bolts when I get home in the morning, but I would bet they are longer than 1.75". I will also post a pic of the oxide coating removed from the tips of the remaining bolts which proves they were bottomed out.

Thanks for the info.

taken19

http://ls1tech.com/forums/generation...-question.html

Good pic of the different trunion design. You can see the upgraded has the bolt head sitting lower, setting the bolt deeper in the threaded hole. Also shows how vendors used to cut the stock bolts and adding threads to make hem work. I still owe an answer to as found bolt lengths and actual bolt hole/trunion length to see if there is enough room.

taken19

So my suspicions are officially confirmed.

Bolts bottomed out in the blind hole. See pic of bolt tips with oxide coating removed due to bottoming out.



Depth of drilled hole. All were within 0.010' of each other.



depth from bottom of rocker arm tray to bolt head surface.




total depth from bolt head to bottom of blind hole.



and , finally, the length of the bolts used.



The best part? The install instructions from Comp Cams. It specifically says to use their supplied bolts that are 1.75" long.



Remember that none of these measurements account for bolt stretch under load and can be off up to 0.010-0.020' due to eyeball measurements, but its DAMN close. The fact that the oxide layer is rubbed off ALL the bolt tips in varying severity tells me that without a doubt the bolts are too long. Now I need to figure out if I can get the piece out of the head without removing the head. No luck so far - stripped the first EZ out.

taken19

Bob, I would think long and hard about installing the stock bolts... use the shorter of the two.

I think Comp Cams has fixed the bolt length issue a while back. I had no issues when installing on my LS2.

Cobra4B

Does the trunion upgrade remove the need to run the rocker pedestal rail? Torque spec for those bolts is 22 ft/lbs with blue loc-tite.

victorf

And since you have not begin the swap, I hope you might find the following useful!

---

In your link, vvlf in Post #10 mentioned problems he had with 15/16" socket being too loose and that he should have used 24mm!

----

This is what I have found, I have 1/2" drive 15/16" sockets made by Kal, Thorsen and SnapON. Also, 24mm socket by Craftsman.

Without measuring, I just fitted the sockets over my three oem crank bolts that I have saved, two are new. I have found 24mm to avoid! Craftsman's fit is definitely snugger and both Kal & Thorsen have the best fit to avoid rounding off the hex head.

---

My damper is an ATI unit, ID of bore is smaller than oem so the offset box end doesn't fit. I faced off the Kal to 1 1/8" to crank the engine by hand.

One other item, some people suggest turning the engine with the alternator, but I've found that difficult and I didn't want to tighten my mechanical belt tensioner so I can do that. Alternator requires either 24mm or 15/16" socket.

victorf

---I don't have a Z06, but some Zs in ls1tech retained the oem for the swap! I would verify if I have a Z!

---FSM never mentioned about using blue loc-tite! Where you get that information?

taken19

Quick update...

First EZ out stripped out yesterday. I guess it didn't bite into the metal well.
Second EZ out (one size bigger) snapped in the remaining bolt.
Third EZ out (even bigger!) caught in the metal but broke the tool that holds it. It stripped the internal threads that tighten it down.

This puppy 'aint moving! I'm gonna have to buy another tool in the morning and try again. I don't suspect I'm gonna have much luck at this point. I'm almost willing to put money on this last EZ out snapping with the new tool.

More to come tomorrow

Rob Willis

Did you try a small amount of heat?

victorf

Like I have responded in your post in Tech/Performance Section on your dilemma, need to work "slow and deliberate" bro.

You are a reactor operator, imagine guys work with double gloves, anti-Cs and airfeed hoods, removing broken super heated inconel alloyed broken stud, in an ultra high temperature/high Rad area.

Again, on your next try, work "slow and deliberate"! Either the vendor relives you of your dilemma or you will be looking at heli coil if the hole is salvageable - after removal!

Wish you luck!