Thread: Possible head bolt screw up...

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So, tonight I was throwing the heads n my 468 and had a brain fart. My dad came over and was checking out the progress and in the process I got distracted and overtorqued one side. None of the bolt felt like they were starting to pull threads out, but they did get torqued to about 95lbs, . I immediately broke em all loose and checked to make sure I had not messed up any threads. They looked fine, so I re-applied the thread sealant and torqued em to 75-80lbs on the long ones and 70-75lbs on the short (I don't have a digital so the torque obviously could vary slightly). They all torqued down all right and nothing felt funny, but I figured I should get a few peoples opinion to either put my mind to ease or make thing worse. Run it or buy ANOTHER new set of head bolts (these just got here today )
Clay

Sounds like you use a standard bending arm t-wrench---good, I like them best for tightening questionable fastners

However----you will not have stripped the threads on your bolts, but if anything pulled the threads in the cast iron block--if they torged back up to spec you are all rite----

the reason I like head studs is that they pull evenly on all the threads in the block where as bolts wind there way down pulling on first one, then two, three, four threads until tight--this is fine for an occasional build but if its on a race engine, will sone wear out the block threads leading to failures

Actually, I normally use an old school bending arm, but this time I was using a click style. The whole day was full of brain farts on my part, lol. I have read you are the guy to talk to about these things so I am glad you popped in. I did not see any signs of block material on the bolts when I pulled them. It is not a race build, but not a stock rebuild for sure. I always re-check torque after a few heat cycles, even when the gasket says it is not needed. Would the thread pull out of the block before the bolts were torqued to the point of not being able to use them?

I guess you are meaning to say that it is fine to use head bolts, but would be better in the future to run studs.

Can I install studs without having to tear the heads off? I really wanted to go studs, but I overspent on a few things so the budget would not allow it. I would like to go to studs in the future for sure. Maybe in the next 6-8 months...

Thanks,
Clay

has to do alot with what you used on the bolts if you used teflon then you can pull the bolts in to a hour glass )( if arp bolts they will take more TQ with teflon past .lower grade new bolts and stocker will start to hour glass at any thing past 75 with teflon . as for pulling threads if weak they will come out with alot less TQ.i been there. if you TQ them back up and did not feel them go soft then your ok you could check the under the head over all to one on the other side that was not over TQ.i think i would of pitch the head gasket less a plate mls. or looked at it very good to make sure the fire rings are not spilting your about 20+ past were you should of been you may say that not much but over all the head bolts thats abit .

The bolts are GM Performance head bolts. Would it be a good idea to pull the head, clean all the bolts up and check them for hour glassing and replace the head gasket? Once the motor is in I can not just pull the heads without pulling out the motor due to how shoehorned the motor is on the jeep...
Clay

Originally Posted by jeepman1320

The bolts are GM Performance head bolts. Would it be a good idea to pull the head, clean all the bolts up and check them for hour glassing and replace the head gasket? Once the motor is in I can not just pull the heads without pulling out the motor due to how shoehorned the motor is on the jeep...
Clay

yes i would look every thing over like i said the over all under the head of the bolt will be longer if over worked as well you can feel it and see it on the thread part of the bolt . looked the heads gasket good

You probably got very close to tensile yield and or failure of the bolts. When they are torqued they will be at about 75% of tensile yield, so you got them up near 85% or so; you should be OK. It does depend on the friction coefficient greatly as to how much you actually stressed the bolts. If you used moly or teflon instead of oil you stressed them a bit more than 85%.

If there is correct engagement length the block threads will not fail before the bolts or studs. They must fail in shear and the shear area is far greater than the tensile area in the bolt and easily makes up for difference in strength.

With all that said I would just replace them if it was mine.

Kitz

the deck is not blind so less it a dart world or bowtie gm it wet so it needs sealer and if you used teflon on them it 95 then what you got if still good ???? lucky. if a old block like jerry said threads will come out if they been on and off thats were studs are nice . i know i put more then one heil a coil in a bbc deck

Yea, they do have teflon on them. I will pull them tonight to check for distortion. If none, then good to go with a new head gasket though...right?
Clay

Pulled a few out and not signs of any distortion with a micrometer... now I am wondering if my torque wrench is reading accurate. I know the last time my dad borrowed it it did not get unloaded and then sat for a while wound up.