SoCalErv

I remember reading that you could measure the head gasket to determine if it was original and thus the engine had never been apart. Am I correct in this assumption or only dreaming?

If I am correct what is the thickness of an original gasket and can it be measured without removing the heads?

tbarb

I believe the original steel shim gasket was .018 and you can use a feeler gauge in the front of the head to get a measurement between head and block.

pop23235

tbarb is correct @ 0.018". It will tell you if you have an original or original equivalent. Not many builders use the original shim gasket.

SWCDuke

The Flint-installed .018" thick plain carbon steel gasket was not available through service parts. The service replacement was .026" thick. I assume that Chevrolet assumed that if a head was removed for a valve job it would be surfaced, so they went with a thicker service replacement to keep the CR in bounds and not get the engine into detonation.

There was a .017" stainless steel shim gasket listed in the seventies vintage Chevrolet Power Manuals. You can see the corners of the gasket at the corners of the head-block interface, and I recall that the OE gasket has a round hole you can see and the SS gasket had a square hole.

Use feeler gages along the front face of the head block interface. Start out small and increase in increments until the gage won't slip in. Once you get a gage that feels snug and a .001" thicker gage won't slide in, you've got the thickness.

Duke