Other than reading the usaul sales blurb and searching the net for info- I'm still sitting on the fence.

Had some problems with my RHS vortecs and am replacing with afr vortec alum. I don't want to talk about quench- my concern is where I live is northern Canada with winter driving at -35C maybe -40C (at that temp C & F are interchangeable) with the alum and iron moving around. I have a set of coated 1094's and GM 10105117 on hand but just found out about GM 14096405 and Cometic apparantly makes a .026 mls vortec gasket- I'm have real second thoughts about the 1094's although they would work well on iron/iron. I won't haggle about cost as the potential problems outwiegh the difference. The engine has got about 10k on it before a valve burned but the decking was not to mls spec- as I recall- I figure clean it well and use copper coat on the block side- arp studs. There was a few stock LT1's around- what did GM use of them oe...BTW this is a TPI 4x4 app.

 

Finally some useful info- sounds like 14096405 or cometic.

I prefer the stainless on one side and graphite faced on the other 14096405 for auto engines and the stainless on both sides 10105117 for marine use. Reason being that auto engines are run hotter and go through many heating and cooling cycles so the graphite face allows the head to move around relative to the lesser movement of the iron block, so the sealing proprieties are longer lived. For marine while the load on the engine is usually continuously higher these engines tend to run cooler and aren't thermally cycled as often while generally requiring sealing that is more corrosion resistant than automotive applications. But I've used both on automotive and marine engines and they worked just fine, so I'm probably over-engineering the situation, a common problem of my personality.

There are three things you need to deal with when you put aluminum heads on cast iron blocks. They originate in the greater chemical reactivity of aluminum so some protection needs to be provided that an all cast iron sandwich isn't concerned about; and the problem of thermally caused differing rates of expansion and contraction between aluminum and iron.

The stainless steel faces or graphite or Teflon works the corrosion issues by putting a material between the aluminum and cast iron that doesn't allow the transfer of electrons from one material to the other.

The build up of a sandwich of gasket material allows movement within the gasket to absorb the differing rates of expansion/contraction between the aluminum and iron without breaking the surface seal with either part. This also reduces whats called "fretting" or "brinelling" which are terms used to describe surface erosion of the one part being rubbed in tiny amounts by another. The sandwhich also allows better conformibility with the surfaces it mates against which is more tolerance for un-flat or un-smooth surfaces.