Cylinder Torque values.

[john107]

Hi guys,
I've just had to replace a Base and Head gasket on my '76 Sport. Now, my mechanic tightened to specs as per the Blue Book and he asked me this question; "Is it still necessary to torque down the head gasket to 2.7kg/cm2 for half a hour to bed it in and then loosen it to 2.2kg/cm2, why not just leave it at 2.7, taking into considering the modern materials gaskets are made from, is this still relevant?" (I supplied him the Athena Gasket Kit). His background is British bikes where you Torque to spec, ride for 500 miles and re-check.

cheers John

[3potjohn]

I have not deviated from the instruction in the Blue Book on the three occasions where I have had the barrels off since 2007. This on my K1.
Others may have a different opinion.
I reused my head gaskets last time around though.
John

[norbert]

Normaly I reuse the gaskets several times as well.
In former times I checked the torque after 500 km. To save some work (taking off the rocker blocks etc.) lately I do the same: a bit more torque, leave it some hours and then the torque recomended.

[john107]

I have not deviated from the instruction in the Blue Book on the three occasions where I have had the barrels off since 2007. This on my K1.
Others may have a different opinion.
I reused my head gaskets last time around though.
John

cheers John thanks for your input.

[john107]

Normaly I reuse the gaskets several times as well.
In former times I checked the torque after 500 km. To save some work (taking off the rocker blocks etc.) lately I do the same: a bit more torque, leave it some hours and then the torque recomended.

Thanks norbert.

[BumbleBee]

If we are talking about the type of gaskets that are predominantly fibre (with a thin strip of metal just around the key places), their thickness settles slowly after the initial torquing down. So benefit from re-torquing as per the book.
However if we are talking about the all metal aluminum gaskets, those are far less compressible, the thickness doesn't really settle much, so many people accept that a single torquing is fine for those.
Sure they can be checked at any major service when the rocker covers are already off
P.S. if you fit an OLD fibre base gasket with an aluminum head gasket treat it like all aluminum, but for a NEW fibre base gasket (even with aluminum head gasket) it could be wise to do the two stage torqueing routine as a new fibre one can compress.

[norbert]

That´s true.
Since decades I only use the all aluminium ones.

[dunk 1]

If using aluminium gaskets and torquing only once do you follow the first of second figure? thanks - Duncan

[BumbleBee]

If using all aluminum gaskets, most people go straight to the final value.

[dunk 1]

Thank you - I think i have a base gasket weep at the minute that needs attention

[BumbleBee]

Thank you - I think i have a base gasket weep at the minute that needs attention

Your choice of course but often base gasket weeps look worse than they actually are. If you aren't having to top the oil up all the time it probably is only a cosmetic problem. Happy riding
P.S. if you have a new fibre base gasket (instead of aluminum both head and base) do the two stage torqueing routine. But old fibre base gaskets ok like aluminum as they have already compressed as much as they are going to.