I was able to buy a big box of NOS Y Block parts from a friend who recently passed away.   In the box were a new set of steel shim head gaskets. I know these gaskets were used to raise compression.  Should I use them in my new motor?  My new motor is a .060 over 292 with "G" heads.  The block and heads have been milled slightly to clean them up.

Shim gaskets were factory installed, not used to increase compression.  If the block has only been cleaned up, then it should be ok.  You will want to verify that you have at least .035" of clearance between the piston and head with the piston at tdc.


Lawrenceville, GA

Are they worth using?  How much do they raise compression above modern composite head gaskets?

The compression change will vary depending on the gasket manufacturer.  On average, there is probably about .20" to .030" difference in thickness which will be about 5cc.

As long as you have sufficient piston to head clearance, the shim gaskets can be worthwhile.  They can be trickier to seal than modern gaskets.  They also require re-torquing whereas many modern gaskets do not.


Lawrenceville, GA

The compression ratio difference on a 292 with the steel shim versus composition head gasket is roughly a half a point.  For calculation purposes, I use 5.24cc for steel shim gaskets versus 10.0cc for the Best Gasket composition head gasket.
 
If your block has been zero decked, then the steel shim head gaskets will be too thin to use as you will not have adequate quench for the piston.  Said another way, the pistons will hit the heads when the engine heats up or is revved up.  As Charlie brings up, the steel shim head gasket do like to be retorqued after that initial warm up.  Be forewarned that steel shim gaskets can be tricky to get the seal just right so that they do not seep coolant.

Lorena, Texas (South of Waco)

Thanks for the information. As my engine in going into a 55 TBird, I think I'll stick with composite gaskets.  Removing the engine and O/D tranny from these cars is no picnic.  Some people say blue Felpro gaskets are prone to leaks.  I have never had this problem.  What is the best YBlock head gasket these days?

I've used BEST head gaskets on the last two Y's and they have worked great..

The best is subjective but Best Gasket have worked with Mummert to improve on the design by removing material from the pushrod area to allow for more clamping force to be applied around the cylinder.  I know a lot of those have been used without issue and it is good to support a company that is willing to improve on things and sees the Y-Block as something that is worthwhile to develop parts for, so Best Gasket is my choice.


Lawrenceville, GA

I also like the BEST oil pan and valley cover gaskets better then the cork type that come in most sets..

Thanks for the tip.  I found the Best Gasket website.  The quality looks good.