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Discussion Starter · #1 ·
I have a E31 head w/ a 280z bottom end. I am trying to torque my head bolts down and they keep on breaking (this happened twice so far). I have brand new bolts, using proper torque order at 3 different stages 30lbs then 40lbs then 60lbs. The threads in my block have been cleaned up. When the bolts break (both have broke flush with my block) they come out really easily. Any advice would be great because I am totally confused.

Thanks Ryan

oh ya, the 2 bolts broke when I was at 60lbs and four bolts back from the front of the engine on each side. I knew the bolts were going to break because they kept on turning far past the allready torqued (60lbs) bolts but my wrench would not click.
 

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Discussion Starter · #2 ·
wow, that's weird. The only way logical to me is that the bolts are too long and bottoming out in the block...maybe run a depth gauge in the block and measure the threads..see if there's enogh room for the thread.
 

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Discussion Starter · #3 ·
I checked that and they are plenty deep. Do I need to buy a new head gasket every time I break a bolt. I think I am going to keep on trying until I get lucky. hopefully 3's a charm, I will find out later today. Thanks
 

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Discussion Starter · #4 ·
If your running a felpro gasket, you need a new one because of the permaseal, if its an OEM style you can retorque it. Where did you get the bolts? I used the old ones on my rebuild, no problems yet.
 

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Discussion Starter · #6 ·
RE: Hercules

Are you pretty comfortable with your Torque wrench calibration, or is it old? Maybe you just got some shitty bolts. Let me know how it turns out.
 

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Discussion Starter · #8 ·
RE: Hole is deep enough,but...

are they threaded all the way down? I had this happen to me 15 yrs ago and I shortened that particular bolt by almost 1/4 inch and torqued it fine. It wasn't that important to me to find out why it broke. If you broke both at the same place, pay special attention to the angle of the wrench. It won't click at an odd angle. You probably know this already thogh. Good luck.
 

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Discussion Starter · #9 ·
<b>RE: HELP. Keep breaking bolts???</b>

Locate a supplier in aircraft grade bolts and you will never break them. The industry standard is about 130 to 145000 LBS. of force. Aircraft grade titanium alloy bolts break at 240 to 260000 lbs. These bolts will pull the the threads from an Iron block before they break. BTW, mine cost less (by about $100) than a complete set from my local dealer and I use them on my race engines. Contact the guys in Calif. and send them a representative bolt to match. Good Luck!
 

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Discussion Starter · #10 ·
<b>RE: HELP. Keep breaking bolts???</b>

Only thing I can add to the excellent above advice is, if they're breaking in the same one or two holes, there's something going on there. I'd yank the head off and clean those holes out real good again. I'll bet there's something in there. Might also use a different torque wrench, even a cheapie one with the pointer just to make sure you're in the ballpark. I've rebuilt many Datsun engines and never broken a head bolt, even reused ones.
 

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Discussion Starter · #11 ·
i have done so many z engines i never had this happen
buy a snap on torque wrench go to a junk yard and
get old bolts out that should solve your problem
remember old is gold.
 
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