I'm wondering if someone might be able to help a guy to learn.
I'm looking for a set of head gaskets for a 425 oldsmobile out of a 1967 Tornado bored +.030
I'm looking for the best set I can find for this engine with this over-bore.
I'm hoping to be as thin as possible.

Thanks, Mike

 

425 over bored .030 has a 4.155 bore.
I'd recommend Cometic MLS Head Gaskets C5809-027

You will need to buy two of them and both the head and engine deck surfaces should be cleaned up for a good seal.
These have a .027 in. compressed thickness which is as thin as you will find outside of the original OEM steel shim head gaskets which are no longer available.

Also refer to this recent discussion on: head gaskets

 

Thank you!

 

X2Don't forget, Head and Deck surfaces must be clean, smooth and square for MLS.

 

Manie,
If it just a stock engine with no modifications i would suggest using the stock replacement Fel Pro head gasket. Part number is 8171PT-1 I just did a 65 425 earlier this year and that is what I used. The Fel Pro gasket is much more forgiving of a not so perfect head and block surface and will work just fine. They will not be quite as thin as the originals but realistically it is not an issue on a stock engine.

The MLS gaskets are very good but require very precise surface finishes and again to be honest with you are not really needed for a basically stock rebuild.

 

The 425 build is an iron head C casting, Mahle +.030 10cc dish forged pistons from cutlassefi, Molnar rods, factory steel crank, Lunati 241/249 @ 050 hydraulic flat tappet, performer rpm with a Sniper EFI. This will be a weekend bracket car ~ 3300 lbs. Cutting the heads and decking to reach ~ 10.4:1 cr.

I most likely should have included that information. I just don't want to do this twice.
All information is taken with appreciation and strongly considered.
Thanks.

 

If that is the case i would go with the MLS gaskets as long as the head and block have been surfaced correctly.

Make sure and mock it up before going too far. You will probably have to cut either the intake manifold or the heads to get the intake to fit on properly. I am doing a 350 stroker with the new Edelbrock heads and I just mocked it up this morning and it looks like I will have to cut at least .060 if not more from either the intake or the heads. I had to cut the block about .015 to get it to zero deck but the heads are untouched.

 

If you are zero decking don't forget about piston to head clearance, .027 kind of tight.