KH500 Head Torque

[David Smith]

Does anyone know what the centre bolt and 8 through bolts should be torqued up to on a KH500 using an Otto head gasket please? Also if the recommended smear of high temperature silicone around the push rod holes should be allowed to cure before fitting, or assembled wet?

I have new through bolts to fit as I snapped one of the originals attempting to tighten the Payen copper asbestos sandwich gasket down to cure an oil leak doh!

I had used Permatex spray on that as well!

I will also skim head and cylinder as required to ensure flatness.

Dave Smith

[Roger Gwynn]

There are not any torque figures listed for these bolts. Do not over tighten and it is more important that they are tightened evenly than to a specific figure. I would suggest 22 ft/lb would be adequate. Silicone when set will not compress sufficiently so would require to applied in a very even thickness. The correct method is to apply a bead, assembly components enough to squash the sealant into an even, thin layer, allow to go off and then tighten.

[paul.jameson]

Torqueing down the head bolts with a torque wrench will be an interesting exercise on a KH. I find it difficult enough with a simple spanner. But I would advise you not to worry about the central stud. I tighten it when first fitting the head on a new gasket (and I am still using NOS copper/asbestos ones) but then ignore it. I have not had a problem in around 20,000 miles - apart from when I tightened the central nut and pulled the stud out of the (alloy) cylinder as a result. The conclusion I have reached is that the centre stud is there to pull the cylinder off the crankcase when you need to remove it by jacking up using the through bolts. Otherwise, removing the cylinder is not an easy job. What you can be certain of is that they didn't use torque wrenches in Selly Oak.

[David Smith]

Roger, Paul


Many thanks, spring balance and spanner then!