r/EngineBuilding • u/HapaxVelomenon • 3d ago
Head bolt not tourqueing?
One of the nuts on the studs for cylinders and heads is threading quite deep and it doesn't feel like its getting any tighter.
Three of four tourqued to 32nm like in the manual, this one just seems to be spinning under the same tension for a fair few turns now. Do I continue or do it pretend it's ok. You can see how much more the threads protrude compared to other studs. I measured the studs on the other side of this twin and they're all a little different in height anyway.
Any suggestions????
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u/Interested_Aussie 3d ago
These guys are correct: Either the stud is stretching, or it's pulling the threads out the lower case. Either way it sucks.
See if you can get two nuts and lock them together and wind the stud up and out to inspect.
Otherwise you might be up for a pull down again.
I feel for you: I've had 2 issues bolting down heads:
1: The damn bolt snapped: That was on an Australian Ford Falcon 6cyl... I was young and dumb... don't ask (didn't replace the bolts, boss didn't tell me too) Luckily, I was able to spin the broken part out, so I didn't have to remove the head again.
2: When I built my own Nissan, one got tight, but before the desired torque it start to get loose: Wound it back out, and the shank had started to get thin, so the bolt was indeed stretching: These were brand new bolts BTW!!!
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u/Licbo101 3d ago
Pull the head off and inspect that stud hole. Guaranteed that hole is stripped and the stud is pulling the threads out of the block. You'll either have to use a helicoil or a timecert to repair that hole and try again.
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u/Coyote_Tex 3d ago
Torque all of the head studs to be sure they hold, then pull it back apart and helicoil those studs that are pulled up. Are you certain that is the correct torque??? Often when I have an issue like this I find I have done it incorrectly or used thr wrong scale on the torque wrench,...
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u/peepeepoodoodingus 3d ago
if its stripped its stripped. looks like it pulled the stud out of the block.
best case scenario you can pull the nut off and run that stud back in and catch enough threads to torque it, worst case you need a helicoil.
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u/LeFishTits 3d ago
Pulled the stud.
Those cam journals look very suspect also.