Composite gaskets

Evening All, I recently bought an engine rebuild kit for my late r reg v8 p6 the kit was described as being for the 3.5 engine with the 9.35 compression ratio which mine is ,however the kit contains composite head and valley gaskets which I have been informed may not be suitable for the p6.Any thoughts please thanks as always


Well-Known Member
Compsite gasket will lower your compression by about 0.6. On a 10.5:1 engine this may not be such a bad thing and allow you to use 95 fuel.

On your car you have three options. Live with a very low compression and loss of power. Skim the head by 20thou. And by far the best of all find some 10 bolt heads from the Discovery or P38 which this gasket is designed for and enjoy 16% more gas flow and proper oil seals while maintaining the compresson as it is now.

As you are putting the effort to rebuild it, I'd swap the heads. If not find a tin gasket, they are cheap enough and work fine given everything in good condition.

What you must do when you put everything back together is do the pre-load on the lifters (the shim kit for the rockers). You can use the composite valley gasket regardless of which head gasket you have.
Thanks for the advice Peter illI probably go with the standard tin gaskets for now never knew about the pre load for the liftersl either so Will be looking that up as well thanks once again


Well-Known Member
If you dry fit the valley gasket and bolt it down with the end clamps and then press it onto the heads you will get an idea of how the fit is around the inlet ports, then you can decide if you want to take a little out of the gasket or not.
I use a long nose die grinder with a 6mm diameter tungsten carbide cutter to trim the gasket, clamping the gasket in a vice and going very slowly.

There should be negligible difference between tin and composite valley gaskets.
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