GIGAPUNK

iTrader: (2)

Speed inc lists cometic gaskets in the following thicknesses (in thousandths):

27, 30, 36, 40, 45, 51, 60, 65, 71, 74, 120

Is there any difference in the sealing ability of a thicker vs. a thiner gasket?

The only reason I can see to go with a thicker gasket (presumming there is no difference in sealing ability/durability) is that it would allow you a bit more compression height on the piston which us LS1 guys are always surching for it seems.

Or does it make sense to start with the thinest gasket possible, just in case the deck needs to be machined for any reason in the future?

I am preparing to build my first long block, and will be using custom pistons. I want to play my squish as tight as possible and was considering trying to end up .002" in the hole and using the .027 gaskets. This is for a big bore NA motor, with a SCR 11.4-11.9.

BigBronco

iTrader: (2)

Well how much power do you want to see? Truly the compression height on the piston helps out if the motor is going to have a lot of cylinder pressure / heat. (Nitrous/Boost applications, etc.)

If this motor is going to stay NA, as I am reading, a gasket that will achieve the SCR and keep a "good" quench size, should be enough for you. Chamber size, Bore size, piston dish/dome, etc.

Overall, most MLS/Cometic gaskets will seal fine, but need a tad more info to help make the correct call.

GIGAPUNK

iTrader: (2)

Ya I guess that it just comes down to being able to deck the head later vs compression height.

But I was wondering, theoretically, if there was any difference in head gasket strength based solely on its thickness.

BigBronco

iTrader: (2)

Well it would constitute to how well the "Clamping force" is. Of course if you can imagine a thinner gasket would be easier to get pressure around the bore orifice, but I have seen gaskets all the way to the .051's withstand some extreme pressures. (That was with 4 bolt style LS' heads)

GIGAPUNK

iTrader: (2)

Trying to imagine the "pressure around the bore orifice" seems like a good way to try and visualize it. And I know that many who have come before me have survived for many miles with way more cylinder pressure than I will be running. There will never be any forced induction or nitrous sprayed on this motor. I do already have head studs.

So you are saying that you believe a thinner gasket to have better sealing abilities than a thick one?

BigBronco

iTrader: (2)

I am saying, with the cylinder pressure your motor will be generating, the gasket will not be the issue. You just need to choose the correct one to give you the right amount of quench/compression for your desired setup.

(Changing that thickness can change/dictate your desired SCR/Cylinder Quench.)