Why did I have to retorque after an engine rebuild

[Davidsquaredson]

Rebuilt my rally 200 engine. Case bolts torqued to 11 ft/lbs. 150 kms run in. Head still tight. But all but 1 of the case bolts needed to be tightened. Studs were not changed but I used new hardware. Why/how did they back off? Will I have check again at some point?





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[fluff34567]

Non locking nuts will vibrate loose.. use a bit of thread lock liquid

[garry inglis]

It's with heat expansion when you first torque your head it was cold then after running those 150 kms it will have expanded and shrunk a few times through cooling and then getting hot again it's daft I No but that's why some engine builders run them for 1/2 hour let them cool then run them again for another 1/2 hour then 're torque this also lets every thing bed in after a build

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[Davidsquaredson]

Makes sense. Thanks for that. I was going to use titanium jet nuts (elliptical threads self lock) but replaced with what was there thinking it was fine for 10 years. I should be good now, will check in 50 kms.

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