Bored today and tried an experiment

[chanlon1]

Replaced my rocker cover recently and had all the old head bolts left over as they are deemed single use.
Decided to see how much you could torque them before they snapped.

When installing new ones on the engine, they say to torque to 7nm, leave 30 minutes and then turn further 90 degrees.

Assuming my old ones were slightly stretched already, I know they weren’t as strong as new ones, however on more than enough of them, as soon as I got to 13nm, they snapped.
12nm and they were fine, 13nm they snapped.

Not highly exciting but killed the time in between rain showers…..

 

[1536Z4]

:rofl: I think that was a great experiment and good to know

 

[Pondrew]

All good, presuming your torque wrench has been calibrated recently.
7-13nm is not a lot, just over 'fully seated' so there is a huge margin for error on a less than high precision spanner.

Passes the time, though, I suppose.

 

[chanlon1]

All good, presuming your torque wrench has been calibrated recently.
7-13nm is not a lot, just over 'fully seated' so there is a huge margin for error on a less than high precision spanner.

Passes the time, though, I suppose.

True - tightening to 7nm isn't much, but when you are doing this for your very first time and they say to go a further 90 degrees....paranoia kicks in very quickly that they'll snap

 

[N4LLY]

Top bombing [ref]chanlon1[/ref] :lol:

 

[john-e89]

Top bombing [ref]chanlon1[/ref] :lol:

Top bombing…. :rofl: :lol:

 

[buzyg]

Top bombing [ref]chanlon1[/ref] :lol:

Top bombing…. :rofl: :lol:

You mean top bolting. :wink:

 

[DMike]

13Nm is next to nothing!

 

[enuff_zed]

Were these bolts magnetic?

 

[chanlon1]

Were these bolts magnetic?

Nope.
Not sure what type they were, but they were very light.

 

[enuff_zed]

Were these bolts magnetic?

Nope.
Not sure what type they were, but they were very light.

So they would have been the alloy ones. Bears out my theory that I was ok to reuse the steel ones I had on mine

 

[pvr]

And now getting the snapped ones out of the block oke: :lol:

 

[chanlon1]

Were these bolts magnetic?

Nope.
Not sure what type they were, but they were very light.

So they would have been the alloy ones. Bears out my theory that I was ok to reuse the steel ones I had on mine

since they had been already used, I suspect they had been stretched to some extent, so its possible brand new ones last a bit longer than 13Nm.