Breaking Head Bolts

[Breitenbucher]

My first attempt to install the head on my 1957 235 snapped off the number 2 position head bolt while trying to torque it to 95 ft./lbs. Ordered a couple of bolts, one long, one short from Chev’s of the 40s. The received bolts were used, long one had paint on it, short one was just a standard grade 8 bolt. I calibrated the torque wrench which was off a little, cleaned off the adhesive spray on the head gasket and tried again just torquing to 90 ft/lb. Again the number 2 position bolt seemed to just keep turning and not making it to 90 so I adjusted wrench down to 80 getting all the way to number 18 (short bolt, original, not the grade 8) and it snapped off. I did put a small amount of oil on the threads and on the shoulder just under the head. Deve doesn’t mention putting oil under the head and perhaps that is what I’m doing wrong. Oil under the head would cause less friction and would stretch the bolt more before getting to the required torque I suppose. Anyone have any ideas? Have all these old bolts been overstressed? Should I just go to the tractor supply and get all new grade 8 bolts?
Thanks, Paul

[Deve]

I don't use any oil under the head and have never had a bolt snap off. Be sure your torque wrench is working properly. I would get new bolts, but I have always used the old ones without problems. Not alot of traffic on this site Paul. You might ask on stovebolt.com and see what they have to say there too.

[Breitenbucher]

Deve:
You were correct, it was the torque wrench which was a new cheap one being used for the first time. I attempted to calibrate it by hanging a 50 lb. weight 16" out on the handle and adjusting it to 67 lbs. but apparently it wasn't repeatable or was different operating it horizontal verses vertical. I borrowed another torque wrench and tested it on a large bolt on a log splitter and it pulled (clicked) at a lot less effort at the 95 lb. setting. This borrowed wrench had a factory calibration sticker covering the adjustment screw so I didn't mess with it. So the third time was the charm and I got all the head bolts easily torqued to 95 ft./lbs. Lesson learned, you get what you pay for when it comes to tools.
Thanks for the help.
Paul

[Deve]

I wasnt being condescending, it is a REAL problem that I see a lot. People tell me they broke off this bolt or that bolt... sometimes they assume foot pounds when its inch pounds, other times its a bad wrench. Believe it or not, I trust the Harbor Freight ones. I have never had one betray me yet. Sometimes cheap is okay. Glad it worked out for you!

[Breitenbucher]

I absolutely didn't take anything you said as condescending, I really appreciate you taking the time to help. The folks at Stovebolt convinced me to throw away the, possibly over stressed, old head bolts. So 'OFF WITH THE HEAD' for the fourth time.
Thanks again for your help.
Paul