Cylinder head bolts????

[sanj72]

Hello folks. I've got a question. Has anyone had a problem with cylinder head bolt snapping? I am currently rebuilding an af05 motor for the 87 & have either snapped the bolts in half at the threads or pulled the thread out of the block. IÔÇÖve had to heli-coil one of the holes). Am I missing something? I am putting anti-sieze on the threads & using a 3/8" torque wrench (husky). I have also uses a smaller 1/4" to make sure that IÔÇÖm in the correct range. IÔÇÖm tightening 6, 9 & last 11 ft/lbs. I have cleaned the bolt holes (& chased the threads) out prior to installing the bbk. Thanks in advance for any input.

[toboggan]

are you sure you're not stripping out the holes, and that's why they're pulling out? make sure to blow out the holes in the block with compressed air.

[mousewheels]

Hmm, 11ft/lbs sounds high. 11 kg-m would be ok.

I looked up the 87 se manual, and its 6-9 ft/lbs.

[toboggan]

i do 11ft/lbs on my bores and they're just fine. But do follow the service manual!

[CharlotteSpreeRider]

11 kg-m would be ok.

11 kg-m would be guaranteed bolt snappage.

[mousewheels]

11 kg-m would be guaranteed bolt snappage.

Thanks - I didn't read the table header correctly - that should be 11 N/m

Guys that think about the physics get it right -- Gee 11 kg at 1 meter...

[Bear45-70]

A snapped bolt is now a two piece bolt instead of a one piece bolt. A stripped out thread hole lets the bolt turn without getting tight.

Once you have stripped the threads in the block you have two choices. Drill out the holes, tape to the next size up (not the right way to go but it will work. Then there are helicoils which makes the threads stainless steel that you are screwing that steel bolt into. This is the proper fix and many top drawer manufactures heli-coil their aluminum casings at the factory ( Volvo does on their marine stuff).

http://www.emhart.com/products/helicoil.asp

If you insist on high torque values you need to Helicoil those poor aluminum threads those steel bolts are going into. More threads in aluminum casings are stripped out by over torquing, than any other damage done to an aluminum block. DO NOT OVER TORQUE ANY BOLT GOING INTO ALUMINUM THREADS, EVER! There is a reason the manufacture set these torque values. To keep you ham handed turkeys from ruining your blocks. Acquire and use a torque wrench and use the proper values.