Cylinder head measurement.

[greenmeanie]

Gentlemen,
I have bought a set of used heads to replace a set messed up by the machine shop. They look to be from a pre 93 RR engine which I presume would have used tin gaskets. I wish to have the heads skimmed to compensate for composite gaskets. My question is what datum surfaces and measurements would you make to determine if the heads have been skimmmed previously? I measured frmo the cyl head mating surface to the flat boss in the combustion chamber as a guide. IS this a good place?

In addition, while the heads are at the shop anyway, I would like to have the valve guides machined to take the later blue valve seals as I seem to have accumualted rather a lot of the things over the years. Can someone measure the modern valve guide and tell me the diameter and height of the nose that the seal presses on to.

Thanks
Gregor

[katanaman]

Pic from the factory manual should do you. First set is standard tin gasket heads, second measurements are what your after and belong to the interim 3.9 heads that were used with comp gaskets. So if you make your heads the same as the second set your good to go.



IMHO if you want to use later seals on the guides then get new guides fitted and you can make them bullited/shortened as well. Its not worth the expense of getting what you have machined just to use the new seals. They wont make it go any faster and their effect on emissions is tiny unless your running the full fuel injection and cats. The proper seals for your guides cost pennies.

[greenmeanie]

Now that's what I call an answer! I couldn't have asked for better info.

Cheers
Gregor