Bored today and tried an experiment

chanlon1 · Post by **chanlon1** » Fri Mar 22, 2024 9:14 pm

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 · Post by **1536Z4** » Fri Mar 22, 2024 9:20 pm

I think that was a great experiment and good to know

Pondrew · Post by **Pondrew** » Fri Mar 22, 2024 9:27 pm

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 · Post by **chanlon1** » Fri Mar 22, 2024 9:53 pm

Pondrew wrote: ↑Fri Mar 22, 2024 9:27 pm 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 · Post by **N4LLY** » Fri Mar 22, 2024 10:19 pm

Top bombing chanlon1

john-e89 · Post by **john-e89** » Sat Mar 23, 2024 1:57 am

N4LLY wrote: ↑Fri Mar 22, 2024 10:19 pm Top bombing chanlon1

Top bombing….

buzyg · Post by **buzyg** » Sat Mar 23, 2024 2:49 am

john-e89 wrote: ↑Sat Mar 23, 2024 1:57 am
N4LLY wrote: ↑Fri Mar 22, 2024 10:19 pm Top bombing chanlon1
Top bombing….

You mean top bolting.

DMike · Post by **DMike** » Tue Mar 26, 2024 10:12 pm

13Nm is next to nothing!

enuff_zed · Post by **enuff_zed** » Wed Mar 27, 2024 8:18 am

Were these bolts magnetic?

chanlon1 · Post by **chanlon1** » Wed Mar 27, 2024 8:51 am

enuff_zed wrote: ↑Wed Mar 27, 2024 8:18 am Were these bolts magnetic?

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

enuff_zed · Post by **enuff_zed** » Wed Mar 27, 2024 8:58 am

chanlon1 wrote: ↑Wed Mar 27, 2024 8:51 am
enuff_zed wrote: ↑Wed Mar 27, 2024 8:18 am 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 · Post by **pvr** » Wed Mar 27, 2024 9:52 am

And now getting the snapped ones out of the block

chanlon1 · Post by **chanlon1** » Wed Mar 27, 2024 12:10 pm

enuff_zed wrote: ↑Wed Mar 27, 2024 8:58 am
chanlon1 wrote: ↑Wed Mar 27, 2024 8:51 am
enuff_zed wrote: ↑Wed Mar 27, 2024 8:18 am 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.

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